Is there any form of security on paid addons

Nope. A lack of DRM goes with the free software culture surrounding Blender.

I obviously can't speak for why any particular addon authors choose to eschew DRM, but it's not uncommon at all. In fact, a number of paid addons are under the GPL and live in public repositories. Gaffer and RetopoFlow, for example.

Gaffer even goes so far as to encourage trying it out before buying; from the README:

  You can download it here to try it out. If you like it, please consider purchasing it from the Blender Market. $20 isn't much, and every sale puts a smile on my face and motivates me to keep developing it :)


Boolean Modifier Red Won't Work or Behaves Strange

It's red because there's no object selected to Boolean with. When I picked the other Cube it worked fine.

The "Cannot Execute Boolean" is because of this beauty:

In this case the geometry was obviously a bit untidy. But it can happen that this similar situation happens at much smaller scales, which are less easy to see without zooming in. In this case the manifold check in the 3d printing tools doesn't pick it up either.


You should try this one. Alt+C -> Mesh from curve then you can merge them by Ctrl+J


The linked video shows parenting with an Offset. If you'd like the two bones to actually connect in your own rig, select Connected instead. Better yet, select the bone roots and hit F afterwards, so your original thigh bone stays nice and aligned with the rest of the leg.


Animating vertices from coordinates in "frame" files

Here is what I did (based upon the answer here):

import bpy #Blender Python
import bmesh #Blender mesh creation pkg
import glob

#function def:
def fileNameToData(filepath):
     #import first data file:
     file = open(filepath,'r')
     lines = file.readlines()
     data=[]
     for i in lines:
         data.append(list(map(float,i.split()[1:4])))
     return data

#number of objects / vertices
n = len(fileNameToData("000.txt")) # (000.txt is the first frame.)

#Read in all data files.
files = glob.glob('*.txt')
files.sort()
data = [] #data is of the format ((frame 1 verts: (2,3,3), (3,6,2), …), (frame 2 verts: (0,5,2), (3,3,5), …), …)
for f in files:
    data.append(fileNameToData(f))

n_frames = len(files)
bpy.context.scene.frame_end = n_frames

#add mesh object:
bpy.ops.mesh.primitive_circle_add(vertices=n)
obj = bpy.context.active_object

for i_frame in range(n_frames):
    block = obj.shape_key_add(name=str(i_frame), from_mix=False)  # returns a key_blocks member
    block.value = 1.0
    block.mute = True
    vertex_idx = 0
    for (vert, co) in zip(block.data, data[i_frame]):
        vert.co = co
    block.mute = True
    block.keyframe_insert(data_path='mute', frame=0, index=-1)
    block.mute = False
    block.keyframe_insert(data_path='mute', frame=i_frame + 1, index=-1)
    block.mute = True
    block.keyframe_insert(data_path='mute', frame=i_frame + 2, index=-1)


Never mind I found it, in the graph editor you change this  to this  at the bottom of the graph editor.


How can I build a model out of hexagons? (honeycomb effect)

You could use "tissue" plugin to achieve similar result.

http://www.co-de-it.com/wordpress/code/blender-tissue

Use on icosphere for dome.


I have a problem making a anvil and i cant seem to find the cause

I think that what you're calling "bad mesh" is the actual mesh without the influence of the subsurf modifier, while the "good mesh" is the result of the subsurf (and actually the result when rendered. When using the subsurf modifier, the vertices should be considered as "control points", which sometimes will not coincide with the rendered forms. To learn how to manage your control points and achieve the results you want, you should search for tutorials about "Hard surface modelling", in particular you'll have to get familiar with Edge control loops and edge crease. Lots of tutorials are available for free, like this: https://www.youtube.com/watch?v=nBkwodrQq_4.


'Matrix' object has no attribute 'z' in world_to_camera_view

Seems like you are passing a vertex though you named it coord.

verts = current_obj.data.vertices
coords_2d = [world_to_camera_view(scene, cam, verts[index].co) for index in face.vertices ]

face.vertices does not contain a collection of mesh vertices, but a list of vertex indices. You need to retrieve the actual vertex and use its coordinate (v.co).


Use Visual Studio for Blender Python scripting

Yes, it is possible. You can use any external editor. If you only want to edit the code, see this question: Workflow for developing add-on/script

A way to avoid the constant reloading: Is it possible to run a script from an external editor without reloading the file?

Other things like correct auto-completion and debugging are also possible, but they require additional configuration, which can be somewhat tricky. Visual Studio is not very popular among Blender developers, I recommend PyCharm or PyDev for this kind of advanced stuff because you can find tutorials for them.


How to add a Line between two moving Objects with Python?

This script will generate a simple single edge mesh, whose verts are hook connected to two pre-existing objects (the cylinders C1 and C2 in this example), which will also work simple animations of these two objects:

import bpy, bmesh
C = bpy.context

# Reference two cylinder objects
c1 = bpy.data.objects['C1']
c2 = bpy.data.objects['C2']

# Create new connector mesh and mesh object and link to scene
m = bpy.data.meshes.new('connector')

bm = bmesh.new()
v1 = bm.verts.new( c1.location )
v2 = bm.verts.new( c2.location )
e  = bm.edges.new([v1,v2])

bm.to_mesh(m)

o = bpy.data.objects.new( 'connector', m )
C.scene.collection.objects.link( o )

# Hook connector vertices to respective cylinders
for i, cyl in enumerate([ c1, c2 ]):
    bpy.ops.object.select_all( action = 'DESELECT' )
    cyl.select_set(True)
    o.select_set(True)
    C.view_layer.objects.active = o # Set connector as active

    # Select vertex
    bpy.ops.object.mode_set(mode='OBJECT')
    o.data.vertices[i].select = True
    bpy.ops.object.mode_set(mode='EDIT')

    bpy.ops.object.hook_add_selob() # Hook to cylinder

    bpy.ops.object.mode_set(mode='OBJECT')
    o.data.vertices[i].select = False

o.modifiers.new('Skin', 'SKIN')
bpy.ops.object.select_all( action = 'DESELECT' )


How to know if the system console is open?

Short Answer: You cannot

First, bpy.ops.wm.console_toggle() is available only on Windows. And I admit, it is a work around. Other OSs run without a console. If you want a console, you must start blender from a terminal on Linux and Mac.

The I/O steam redirect blender.exe > out.txt should work. (but I haven't test it)

If you realy want to communicate with user, you should use a dialog box:
http://wiki.blender.org/index.php/Dev:2.5/Py/Scripts/Cookbook/Code_snippets/Interface

error message or save it in a log file. Those methods should work on any system.

P.S.

On C code side, the function returns the current status, and you can query the status.


Instead of filling the face and insetting, you can extrude the edge with E and scale it down by pressing S afterward.


You can do this by using Position texture coordinates.

Just use the Position output of the Input > Geometry node for your texture coordinates.  This uses absolute world-space instead of the scaled local-space, so the textures will not be stretched.  To get it to map from all directions, select Box on the image texture node.


You have material override in render layer:

It replaces all materials in the scene by this one. Remove material from here by clicking cross-icon


Geometry Nodes - How to assign vertex group in geometry nodes?

If I’m interpreting your question correctly, and you just want to restrict the set of points where instances are created using a vertex group, you can use the Point Separate node:

In this example, my vertex group is named “no cubes”.
If you want the inverse, i.e. you want the cubes to only be instanced at the vertices contained in the vertex group, then you can use the Geometry 2 output of the Point Separate node, instead.


In render tab - color managment set Display device to sRGB

Maybe, it is a good point for 2.8 start with factory settings.


How can you set Blender's Theme Preset with python

I found a way but I don't know it is right or wrong to do this way
The way I did is -
In the dropdown menu of themes just right click on the theme you want to change to and then another menu will appear > click on copy python command > and then paste that command in the console > and if you want to change the theme from the console you need to remember the theme name > you can change the name in the command where the file name is written (maya.xml, or modo.xml, etc).
Step 1-

Step 2-

Step 3-

Step 4-

Step 5-

Step 6 -

And in this way, you can change the theme from the console


Bevel Start End on Circle Curve, Blender 2.83 not working

Either Blender is rather non-intuitive, or I'm missing something obvious.
The fastest way I found:

Add a bezier circle and make it non-cyclic (Alt + C)
Rotate the end vertices to form a 3/4 circle
Extrude one of the ends and complete the circle


How do I make wine bottle reflections blue?

If you want tinted reflections without tinted transmission, you can put your glass together manually-- it's relatively simple.  It's just a refraction BSDF mixed with a glossy BSDF on the basis of Fresnel:

Shown here with a red reflection, but of course, you can use anything you'd like.


Why is my lattice drastically deforming its mesh?

You must not scale your Lattice in Edit mode or it will completely screw the object it is linked to, as it's happening right now, because it takes all these scale deformations into account when you link your object to it. Make all the scales you need in Object mode. Then you can enter in Edit mode and move the vertices or scale to deform the object, but before that, keep the initial shape as a Shapekey so you can come back to it whenever you want. So I guess you have to delete and redo your Lattice.


Is there a quick method to make a sawtooth structure?

For repeated shapes, the obvious answer is “make one copy, then add an array modifier”. You can apply the modifier if you want to further edit the geometry, otherwise you can leave it in place.


Is there a way to get the location of the starting position of a curve?

Well, I don't know how good of a solution this is, but as suggested by @batFINGER this worked for me.

if parent.type == 'CURVE':
    if parent.data.splines[0].type == 'BEZIER':
        curve = Matrix.Translation(parent.data.splines[0].bezier_points[0].co)
    else:
        curve = Matrix.Translation(parent.data.splines[0].points[0].co)

    mat = parent.matrix_world @ curve

matdupe = obj.matrix_world.copy()

obj.parent = None
obj.matrix_world = matdupe
obj.parent = parent

if parent.type == 'CURVE':
    obj.matrix_basis = mat.inverted() @ obj.matrix_basis
else:
    obj.matrix_parent_inverse = parent.matrix_world.inverted()


Cannot mix .user and .addon keyconfigs in register()

OR use .active without it telling me 'Mesh' keymap doesn't exist

Have you tried checking for and adding it if necessary?

kc=bpy.context.window_manager.keyconfigs.active
km='Mesh' in kc.keymaps and kc.keymaps['Mesh'] or kc.keymaps.new('Mesh')


Some Data Failed to Reconstruct, Motion Tracking

Blender is failing to reconstruct because it cannot get enough good tracking information to reconstruct the 3D motion for a section of the video, so it reconstructs only a portion of the shot. The frames where it failed are marked in red.
There are many reasons why your shot fails to track properly making the 3D reconstruction impossible.
I'll address a few.
1- A successful track is determined primarily by the quality of the shot.
Blurry, distorted images will be much harder to track than clear, sharp ones with unique features in which to anchor the trackers.
In this case, you're getting "rolling shutter distortion" or "jello effect" from the sensor of the camera on your iphone. The movement of the camera makes the image dance all over the frame giving the trackers false information.
-To correct that you would need hold the camera steadier, or undistort the video using other tools like Virtual dub or warp stabilizer on adobe premiere or afterfx.
In parts of the shot the camera moves way too fast. The image has so much motion blur that the trackers no longer have enough features to follow.
-solution: Do not move the camera so fast, so the image stays sharp.

The scene itself has very few distinctive features to anchor the trackers on. The cement floor and the wall have almost the same texture, so blender has a hard time finding specific points from frame to frame. The best tracking points in an image are those with unique features and sharp contrast.

-Solution: Find a distinctive features in your scene or add them to make the tracking accurate. You can do that with bright tape or with a color that is not part of the scene (you can also use marbles or colored balls). Those markers you can remove later.
2- The way the camera moves in the original shot determines the kind of camera solving that is required.
The default camera solver in blender presumes some parallax, or change in perspective, like when you walk and objects in the foreground move faster in the frame than those far away.
If the camera is static on the same place (not advancing laterally or going up or down) but just rotating or tilting, then the shot cannot be solved with the regular mode in blender.
-Solution: You have to use "tripod solve" (even if your camera was not on a real tripod). That solution will give you a 3D camera that mimics the original move and the tracking points will be projected form the camera, not necessarily reconstructing the  geometry of the original objects. In tripod camera solving it is much harder to accurately estimate distance.
3- Accurate tracking is the only way to get a proper solution.
The error messages and red bars you see are all the frames blender couldn't reconstruct and are listed as the errors on the console. This happens as the result of blender not having enough information to accurately recreate the camera in the 3d environment.
Solution: Refine your trackers, make sure they don't slip or start tracking unwanted parts. Delete trackers with errors (use the clear track forward/back tool). Play with the correlation values when the tracker fails. The goal is to have a solve error as low as possible. If you can get it to be around 0.3 you'll be fine
(But you can save yourself some time by going out and shooting a new video keeping in mind all of the above).
good luck!
FOR MORE TIPS ON MOTION TRACKING READ THIS POST


Download and install MakeHuman this allows you to create and customise a human model and add a rig. The model (with rig) can then be exported in a format that can then be imported into Blender.


To assign a hotkey you do not have to code :)

Go to Edit > Preferences > Keymap
Assuming you want to trigger the hotkey in edit mode, find 3D View > Mesh > Mesh (Global)

Scroll down until you find  + Add New  button. Click it and you should get

Expand and replace none in the identifier field with your operator id and assign the keyboard/mouse shortcut.

Go to edit mode and test!!


According to your file, IK limits are defined. You need to unlock related axis, or set appropriate angle ranges for consistency, in order to avoid control conflicts.


Make sure that you have the max bounces set adequately high to show full global illumination effects. There is a preset that you can activate as well. You may also have to increase the intensity of the light source and adjust the exposure. The distance, size or intensity of the light seems to be different in your first render, because the shadows are much crisper than in the second.

Plane with Principled BSDF (Specular 0.5, Roughness 0.5)

Plane with Principled BSDF (Specular 0.0, Roughness 0.5)


You can use a Color Ramp node and a Modulo converter node to achieve this result.

Set up your nodes like this:

And this is the result:

What you are doing is you are making the Color Ramp node tell what color, and then you are mapping it using the Mapping node, and repeating it with the Modulo node. This makes it fully editable, you can change the color ramp, and the resulting texture will repeat endlessly.


Blender searches for addons in three places, one of which is /Users/{user}/Library/Application Support/Blender/2.72/. If your addon is already there, then it is "installed".
The install from file button in the user preferences essentially just copies files into this directory.

If you don't see the addon listed in the user preferences, then there may be something wrong with the addon. Try starting blender from a terminal and see if there are any error messages.


[SOLVED] I fixed it. How it happened is unclear to me, but changes in Edit mode of the rig did not affect the model.


I just had the same problem after downloading this new Blender version.

If you open this Falloff menu, then there is that Falloff Shape.
Changing it from Sphere to Project work for me.


blender game - animation of skeleton - not playing

Put the action actuator on the armature not the mesh object.

When an action actuator is triggered the object it is related to is the one performing the action, the action you setup has no effect on the mesh object.


It appears that you are in local view. The plane appears to not be integrated in the render layers. Perhaps you have added it in local view (it looks like a bug)?

Simply press the NumpadDivision key (÷) to exit local view.


Animation jumps as if it isn't interpolating properly

Ok, I figured out the problem. I had edited the rotations manually, and the w of one of the quaternions was negative, which seems to mess with the rotation. You can normalize it by setting the rotation to a format other than quaternion, then putting it back to quaternion.


How to get/write an index for a modifier in a list box?

You can create a simple IntProperty() to be used as active index storage.

bpy.types.Object.modifier_active_index = bpy.props.IntProperty()

# ...

row.template_list("UI_UL_list", "list", ob, "modifiers", ob, "modifier_active_index", rows=rows)


The Interactive Navigation controls can be toggled by pressing the gizmo icon in the upper right corner of the 3D view or by pressing ⎈ Ctrl` (backtick not single quote/apostrophe).


Consider using freestyle.  Please search freestyle. There are many video tutorials on freestyle. Then show your work.  You may want to use freestyle with Blender Render to reduce time during your learning experience.  You can use the compositor to combine lines with a regular rendered image.

Also you can use the compositor put lines around objects all by itself.  The line can be a glow.  This is possible because Blender can reveal contrast between a transparent background or object id and the surrounding image.


Shadows not influenced by normal map in BI

A normal map on a plane will fake the shading, but will not deform shadows projected on the plane.

Essentially the shadows are those of the underlaying plane.

To create real displacement: add a displacement modifier using a texture.
(Note you might need to subdivide your object and create more vertices to displace.)


This is caused by the inaccurate behavior of Shadow Mapping used in real time rendering enginnes like EEVEE and almost all game rendering engines. People call them Shadow Acne.

What you see is actually pixelated shadow mapping to some boundary area, causing those alias shadow show on the mesh.

There are many solutions to overcome this problem, but since performance is the main issue in real-time rendering, the best solution changes depend on the situation of your application.

You can check out this explanation about shadow mapping: Shadow Mapping - LearnOpenGL

Blender 2.81 Update Information

According to the latest Blender,

  Soft shadows were changed and now enabled with the Use Soft Shadow option in the render properties Shadow panel. This will progressive smooth shadows, in combination with a more conventional shadow filtering method (PCF). Exponential and Variance Shadow Mapping methods were removed. (d8aaf25c23fa)

The way EEVEE render shadow has been changed to a more common method. And the problem of Shadow Acne should be reduce or even solved. Check for the latest Blender to see whether the shadow has been fixed.


Does Blender support threading for data processing?

First of all, Cycles render is an additional application with its own kernel, written in c/c++. It is ''glued'' to Blender by several Python scripts, well I think so.

Secondly, you can use Python modules like threading and multiprocessing to process data simultaneously. They are built-ins in Python interpreter, so there shouldn't be any problems if you'll decide to distribute your script.


How can I determine/calculate a circumcenter with 3 points

I have written such a tool, it creates a grease-pencil representation of the reconstructed circle if you can select 3 vertices of an incomplete circle. It also allows you to change the number of vertices of the new representation.

You can easily convert from grease pencil to mesh

6 mb example image


Can i control emission brightness using an object controller with animation nodes?

There are multiple ways to do this, one way is to send the location and scale of the controller object to the material and compute the distance between the locations of the pipes and the location of the controller in the material:

How you use the distance is up to you.


Select multiple overlapping islands in UV Editor?

You can use Box select, which is activated with B:

You can also use C for Circle Select and CtrlLMB for Lasso Select.

For more on selection tools in the UV editor, see the wiki.


First you must set the crocodile mesh to no colision and child of the armature, and the armature also to no colision and child of a cube that will be your colision bound. actually that cube is your crocodile and it will interact with physics and logic, the armature and the mesh must be merely visual.


Yes a mesh can be a child of a single bone. This is possible.

In pose mode select the bone of the armature. Object Mode again for convenience.
Select the Mesh.
Select the armature to parent Control P ... Menu Choice Bone
Note the parent is Armature with Bone Subchoice


When in Wireframe mode and selecting an egde, only the top is selected and not the whole vertices

In the video (at 2m16s) he forgot to mention that just before selecting the vertice he is pressing the C key, C for Circle select.

He explains about C for Circle select at 2m30s as he is selecting the next corner vertice.


Why are objects appearing as a "ghostly" image after rendering?

Try using an Alpha over node instead of an add node:

The add node literally adds the pixel values of one image to the other image. This means that not only will you have both images visible at once, but you could end up with pixels brighter than 1.


Blender Boolean modifier: Difference behaves like union

You are trying to use a simple plane as boolean operand here - which is by definition not manifold (a manifold surface must be closed, since all its edges have to have two and only two faces). Behavior of booleans in this case is never really ensured…

Also, your 3DView only shows objects enabled for rendering, and your 'ObjA' object is disabled for rendering, so it's completely hidden from 3DView.

Other than that, I see no issue with this .blend, if there are please be more specific.


Why is Blender Exporting to Unity as a Rig?

That is just how Unity reads .fbx files, because they can have rigs in them.

It doesn't mean your building is rigged though.

Go to the rig tab, and make sure it's set to either none or generic (I can't remember fully the options, I do not have Unity to hand to check)

Unity doesn't have the ability to edit raw geometry as far as I know, so it wouldn't be deleting polygons. This is probably an issue with normals, check your normals in blender, and make sure whatever shader you're using is double sided, ie no backface culling and that should clear up your issue.


Show current image from node editor on viewport's mesh

This, I believe, is a feature from the Node Wrangler addon

Never used it myself but it apparently creates a temporary emission shader to act as a texture viewer in the viewport.

Hotkey is Ctrl + Shift + Left Mouse button Click as illustrated in the wiki page by Greg Zaal.


Select the armature, you can see that you've parented it to the mesh, an object can't be both parent and child of another object, so deactivate the parentage. Also you'll need to remove doubles in your mesh, otherwise you won't be able to parent it.


Entire set of objects snapping to rotation instead of single object

A friend had told me that the body and wings were sharing one animation so I had to make a new action and key frame the wings separately.


Is there a way to calculate the volume difference between two objects?

If you go to edit>properties>Addons and enable the 3d print toolbox add-on then click on the 3d-print tab on the right side of your viewport you can click volume to get a numerical value for the volume of the object. From there you can either get both volumes and do the math yourself or you can bool the 2 objects and use the 3d-print tools to get the volume of the result.


You have two materials for one object: StriaStripe and StriaPlum. StriaStripe is on top and was put on the object first, and therefor the object is shown with that material.
If you delete StriaStripe in the Material Properties tab, the object will only have StriaPlum as a material, and then you can see it on your object.
But maybe you don't want to delete it.
In that case you have to select StriaPlum in the Material Properties (click it and it will have a gray bar over it). Then go into Edit Mode with Tab  and press A  to select all the faces of your object. Then click Assign (under the material list in the Material Properties tab), and the faces will get the selected material. Now the object is shown with the other material.
So with the Assign button you can give different materials to different faces, and one object can also have a material on part of the faces, and another material on other faces.


You need to add a Composite node with the same input as your Viewer node.

In order for anything to be composited in the Render Image you must have the Composite node, otherwise the Compositor is skipped entirely.


If you simply want it to follow one of the tracks, what you're looking for is the 'Track Position' node (in the Input section of the compositor node list).  Just give it the video clip and a track that's the same depth as the effect you're adding.  Excuse the lack of actual files in this example, but in the compositor, create the following (vector blur is optional):

You may need to add another transform node to just the EXR sequence so it lines up correctly.

Just to cover my bases, if you need a more 3D layering, you'll add the sequence to the Blender scene projected onto a mesh, plane or otherwise.  To include alpha as part of the plane, you just need to use the alpha as a factor of a mix shader:


How to render individual objects (one per frame)

You can easily do this by assigning an Object ID index to each object that corresponds to the frame in which you want the object to appear.

Then in the compositor, you set the alpha channel using the IDMask node. The trick is to then add a driver to the Index value so that it uses the frame number as the Index value on each frame change.

To add the driver, right click on the Index field in the ID Mask node, and select Add Driver. Then, with the node still selected, open the Graph Editor and switch to Driver view. The default driver type is Scripted Expression, and all you need to do is enter the value "frame" in the Expr field of the driver settings. Now when you change the active frame on the timeline, the ID Mask node will update the alpha channel to filter out all other objects and just show the object with the Object Index ID that matches the current frame number.


This is most likely because you did not change the location of the fluid bake. Set the fluid bake location to an empty file on your computer separate from the other bake, and try again.


Animation transfer from one rig to another

All the animation data refer to the bone's names, so if you give to your new rig the same bone names it will work. Data with different names will be ignored.


Rigging Automatic Weight not working right

To answer your question, your weighting is now entirely off, but you can fix it via weight painting. The parts you want to move should be red, with a bit of a falloff into yellow and green as it merges into the other bone.

HOWEVER, since you've sculpted, and it's not intended for animation, there's a much easier solution. Try using a lattice! Add a lattice to your scene and move and scale it around to fit the arm as well as you can (do not do this in edit mode! it'll mess up your results!). Then apply a lattice modifier to your sculpt, and select the lattice you just made. Now you can go into edit mode. Before you touch anything, add some more points to work with over in the modifier settings until you have enough to bend it. It shouldn't take many. Now all you have to do is move the lattice around until it looks like you want.


By using collision callbacks you can retrieve the hit object, point and normal (not sure about how to retrieve the impact force though). See the API reference for more info. Example file below.

def my_callback(object, point, normal):
    ''' Do whatever you want with your collision data '''
    print('Hit by', object.name, 'at', point, 'with normal', normal)

def register_callback(cont):
    ''' Run this with an always sensor (tap enabled) when the game starts '''
    own = cont.owner

    if not my_callback in own.collisionCallbacks:
        own.collisionCallbacks.append(my_callback)

Example file:


How can i set a line to be an exact measurement

Scenario 01
In Object mode just change Dimension. Than Apply Scale  Ctrl+A to bring scale factor to 1, then you can see edge length in edit mode as dimension. Think about Object as an universal container that can contains any data set. (If you go to Data Properties of selected object you can assign any data set to this object container.) By changing dimension you actually change just a scale factor for this container not data itself.

Scenario 02
In Edit mode you can select edge, press G move X along axis and type number like a math.
Let say if you have side 2 m and you want 1 m, type -+1.

Scenario 03
You can delete all vertices. Click with Ctrl (create vertex), press E Extrude along X axis and type number of specific distance. Than same for edge to extrude second dimension.


How can i animate my object with one bone?

The correct procedure in to select in object mode the mesh first, the armature second (with shift select), then press Ctrl P and choose with automatic weights option. In this way moving in pose mode the bone will move the mesh strictly tied. Another (and better) way is to choose the "bone" option, which can be used when the mesh doesn't have to be deformed (in your case, in which you have one bone only, the result is exactly the same).


How to append .L and .R to my vertex groups with script - AND maybe how to duplicate

There are three problems currently.

You seem to have pasted the code into a text-editing programm with has encoded the script, then opened it up in Blender. Most likely the ending of your file was .rtf. As you can see in the text editor of Blender, this introduced numerous characters which we don't want. Right now your script starts with {\rtf\ansi ...
You have to simply open the text editor in Blender, paste the script directly, then press Run Script.
If you really want to edit your script externally, use the ending .txt or better .py (the python extension).
You have replaced the command startswith with beginswith (accidentally probably).
You are not using single quotes ', but other special characters ‘ and ’. The were probably generated by your text-editor as well. Use a simple texteditor instead, such as Blenders builtin text editor.

Here is the corrected script.

import bpy
obj = bpy.context.active_object

vg = obj.vertex_groups[:]
for g in vg:
    if g.name.startswith('b__R'):
        g.name = g.name+'.R'
    if g.name.startswith('b__L'):
        g.name = g.name+'.L'

However, I would suggest more changes.

Using the same script to toggle the ending on and off.
Comparing parts of the name with the slice notation.
E.g. to compare the first four characters: my_name[:4]
Replacing the ending letter with the fourth (fixed) L or R character.

These are a lot of obstacles for a beginner, here is the improved (changed) script, the benefit beeing to only need one.

import bpy

obj = bpy.context.active_object
for g in obj.vertex_groups:
    if g.name[:4] in ['b__R', 'b__L']:
        if g.name[-2:] in ['.R', '.L']:
            g.name = g.name[:-2]
        else:
            g.name = g.name + '.' + g.name[3:4]


inverse kinematics with bone constraints only work, if i stop cursor movement and release mouse button

Okay, so after seeing the .blend, I was wrong in my comment.  (Because there have apparently been some changes made to how Blender handles IK.)  However, these changes made to Blender aren't really great changes, and I'm still going to recommend doing it the old fashioned way.
So, first, let's explain what's going on.  You are moving the chain via IK.  The IK algorithm doesn't know about the limit rotation constraints that you've set for the IK bones, so while you're moving it, it's not using any these constraints.  However, at the point that you confirm, it's then evaluating those constraints and so changing the bones' transforms.
Limiting the angles of IK with limit rotation constraints is, well, kinda hacky.  Hopefully obviously here.  (Limit rotation is a deceptively hard constraint to use well anyways, for reasons that are spectacularly math-y, particularly in world space like you're doing here.)  It looks like Blender devs have tried to make it work, but it doesn't work well.
A much better way to get the IK you want is to delete these constraints and use IK angle limits and locks.  You can see these by selecting a bone in pose mode and then looking at properties/bone/inverse kinematics.  In this particular case, we want to lock Y and Z axes for all of the bones:

Note that these are no longer world-space limits on your rotation, like you had with your constraints, but I'd bet a lot of money that you didn't want them world-space anyways.
With this setup, it works fine for me-- but I'm still wary of the unusual structure.  It's typical with an IK setup to designate a target for the IK constraint, but if this works for you, that's fine.  The more typical way to do this would be to put the IK constraint on Mid, give it a chain length of 2, duplicate and unparent Upper and designate this duplicate as the target of the IK constraint, and finally give Upper a copy rotation constraint targeting the duplicate.  (Which could be followed by a limit rotation if you wanted.)


How can I put separate images together to create an animation on Blender?

Switch into Video Editing layout and focus on Video Sequence Editor.
Press Shift+A -> Image (or select Add -> Image from the menu bar).
Select all images you want to create the video from.
The video strip based on the image sequence will be automatically created.

Then you can of course render it to a regular video format.


Is it required converting videos to an image sequence before doing motion tracking?

You don't necessarily have to convert video to an image sequence.
While it is possible to decode and track without having to use an image sequence, some videos will work and some will result in errors, depending on how they are encoded.
Blender is not broken, but can only work with video that is encoded with certain specific parameters.
Video encoded with intraframe compression will work fine. Each and every frame containd all of the information, so it does not depend from the
information  of previous frames or any of the frames that come after it (same as with an image sequence).
Video encoded with interframe , or long GOP compression, will likely yield errors, since the information needed to decode each frame is dependent on adjacent frames, and only the differences are calculated. In other words, there is a key frame that has all the information, for the next few frames only the differences are calculated, but to decode those frames you need to reference the keframe everytime.
Also, if the video is encoded using any kind of variable framerate (some phones use this to make small files, as well as some screen recording software), then it needs to be re-encoded and conformed to a uniform and stable framerate, before being imported in blender.
Blender will not do on-the-fly framerate conversion or temporal interpolation in any way.
For more information read: http://www.leckman.com/articles/codecs_05.html


You can access the pixel data directly through the Image.pixels property. It is a list of repeated RGBA values. To access a single pixel, use this:
img = bpy.data.images["Render Result"]
value = img.pixels[(y * img.width + x) * 4 + channel]

where channel is 0 for red, 1 for green, 2 for blue and 3 for transparency.
Now, image brightness is not a clearly defined thing. You can, for example, calculate the average pixel value over the whole image:
r, g, b = [sum(img.pixels[:][i::4]) / len(img.pixels) for i in range(3)]

That was "average" as in "arithmetic mean". Another possible interpretation of image brightness is a quantile, say, the 95th:
import numpy as np
r, g, b = [np.quantile(img.pixels[:][i::4], 0.95) for i in range(3)]

The specific choice probably depends on the kind of images you are processing.


I think that this rig is intended to let the user stretch the legs, so during animation process you can choose if to leave the foot close to the leg without stretching or move it away with stretch effect: note that bones do not stretch at all, only mesh does. If you want to constraint the foot to the leg, the foot deforming bone (which in this rig is reversed 180 degrees) should be parented and connected to the leg bone; the IK controller should be positioned at the end of the leg bone, but parented to the main character controller, so that moving the IK controller will move the leg chain, and the leg chain will move the foot, always connected. There are many ways of rigging a foot (which is the most difficult challenge in rigging human body): my favourite is this, which is pretty similar to the Rigify's one: https://www.youtube.com/watch?v=VVHKBSknFhA&t=6s


This can be accomplished with the "slow parent" settings. They are found under Properties > Object > Relations Extras. Open them up under the camera and turn the offset up to, say, 9.00. This will give a lot of drag between your camera following the player; When the player moves, the camera follows loosely, just like you wanted. If you want a longer time between parent movement ad the child movement, increase the offset, less time, decrease the offset.


You can find the defaults by opening a new instance of blender and loading the defaults (without saving the default.blend) and using python to get the default values:

import bpy

for light in bpy.context.user_preferences.system.solid_lights:
    print(light.direction)

Which will print:

<Vector (-0.8920, 0.3000, 0.9000)>
<Vector (0.5880, 0.4600, 0.2480)>
<Vector (0.2160, -0.3920, -0.2160)>

So to set the light directions to the defaults, run:

import bpy

bpy.context.user_preferences.system.solid_lights[0].direction = (-0.892, 0.3, 0.9)
bpy.context.user_preferences.system.solid_lights[1].direction = (0.5880, 0.4600, 0.2480)
bpy.context.user_preferences.system.solid_lights[2].direction = (0.2160, -0.3920, -0.2160)


Weird behavior when moving or scaling or rotating default cube or any first object

Ok I know the problem. I had this before. Deselect evrything in the edit mode then go back to object mode. To deselect click to an empty place or press A 2 times fastly.

I don't know what is this problem about but you need to deselect everything in edit mode before going back to object mode.

After I updated my graphics card driver it is not a problem for me anymore.


Can you use vertex weights for modeling?

Maybe use Shape Keys with vertex groups set as mask through Blend option?
As a bonus it is a non destructive workflow.

Won't work for very complex transforms, but for most linear motion should suffice


Maxon's Cinema 4D is a closed and proprietary tool and there is no way to access the .c4d file in a legal, safe and usable way other than C4D itself.

But you can use one of the many other export methods available.

".obj" , ".fbx" , ".dae" .... for simple mesh transfer and Alembic (.abc) for dynamic and advanced export.


How to join two objects with different color

Multiple possibilities:

OR: Import your (I guess svg) X object as 3 objects instead of 2. In Illustrator, you can use the "Pathfinder" panel to slice 2 objects in 3 objects.

OR: Dirty fix: bring the red part slightly closer to the camera.

After one of these fixes, you can join both objects (ctrl j) in Blender and extrude them as 1 object.


Inconsistent visuals between Material view and Rendered

Seem to have solved my own answer.

From what I understand I linked 2 Color ramps to different Fac areas relating to my "sticker" and its gloss causing a white fill effect in material view while not showing in rendered.

I guess the moral of the story is make sure everything links to the right place.

Thank you Duarte for the comment telling me to check if the right node types are connected.


You need to pixelate your UV coordinates which you can do as so:

x - (x modulo pixelSize)

You can then use the same modulo nodes by normalizing their outputs to get the coordinates for your discs:

(x modulo pixelSize) / pixelSize

Create your discs the same way you have already done and use them to mix between your image texture output and a background color.

I hope this helps.


Limiting the amount of frames a mask is active

Add a color mix node, on the unconnected socket set the color to black. By animating the factor for the mix you can control the opacity of the mask.


How to create a most basic texture on an object?

Most basic approach in Cycles:

Unwrap the cube in edit mode.

Create a new material.
In node editor, add an image texture and connect to material node.

View in render mode.

EDIT: You can make textures without nodes... sort of. And you can certainly make textures without using images.

But Blender, Maya, 3ds etc are all node based. You can "hide" this fact by making settings in the data block areas, but nodes are what is really happening... which is to say changes you make in the materials property area, at right in image below, are actually just adjusting nodes. You don't have to "use" nodes, by which I mean see them, but they are their nonetheless.


Normal Map gives black render on half the surfaces

You need a Normal Map Node between the Image Texture and Principled Shader.

Now beware that this Strength parameter is in units at the scene scale, so most likely by default this is going to try to make it appear such that the highest point is jutted out by an entire meter.  It has to do this without affecting the geometry so it is likely to also give you some visual artifacts (such as pure black cracks) right out of the box.
I usually set it to .3 or lower before I even enter rendered view, and then adjust by eye.


Editing lighting on the sides of a cylinder

Out of curiosity, I added 2 edge loops to the cylinder, and that seemed to fix the problem I was having with the lighting. I've only been using Blender for a few weeks, so I can't explain why that fixed it, but it did.

The wireframe with the additional edge loops highlighted:

And now the lighting affects the entire edge.


Use your image to control the mix between a glossy and a diffuse shader:


Using Texture Nodes for the Displace Modifier

It'd be nice if this worked, however as an alternative you might consider using cycles displacement.

Here's a simple example of what's possible. This scene is made up of one plane, with no displace modifier:

Note that it's an experimental feature, so you'll have to enable experimental features first, and you may encounter bugs. If you do find a bug, report it and chances are it will be fixed :)


From what I have seen, you should try adjusting the merge distance. This can be found in the bottom of the tools panel after you remove doubles.

This process will adjust the limit for considering something a "double".


How to correct Blender "physics visualization" inconsistancy with base mesh made of quads

It is always a bad idea to use quads... especially when it comes to games where you have physics and collision calculations. Everything will get converted to triangles anyway, for optimisation and accuracy purposes.
I couldn't exactly understand what the exact problem was, but whatever it is it would have something to do with the quads.
Always triangulate before you use your mesh for simulation.
And if it is just because of this guys script that you keep a quad surface, then either edit the script that it takes in a triangulated mesh, or find a different LevelOfDetail (LOD) script.
PS: I am pretty sure he would be converting to trinagles somewhere in the script anyway, as it is not possible to get continuous LOD with quads


I guess the proper way to do this would be via compositing, but in Cycles, the Light Path node can take you some way.. it's a bit of a fudge, and may depend on your scene:

The torus in the little shot below uses this tree:

'Is Transmission' ensures that the torus material will emit whenever seen through another transmissive material, and is 'OR'ed by the Maximum with:
'Ray Depth > 2', which means that surrounding objects appear illuminated when seen through the glass, but not otherwise.. the discrimination isn't perfect in all situations, there might be a tiny bit of bounce from the torus when not seen through the glass, but seems good here:

(The glass is 2-sided, it has thickness)


How to make object non-transparent in viewport?

Turn off "Show backface" in the material settings. You'll have to do this for all the materials individually.


Blender subdividing faces and creating edges where shouldn't be any

The face where you are seeing that extra fold is twisted, its top edge is rotated from its bottom edge. So it isn't possible to render it with flat shading, and Blender thus calculated a bend there.

To avoid this, turn on smooth shading on the object - in object mode, press T while in the 3d viewer to open the toolbar, then go to the Shading section under Tools > Transform, and click the Smooth Button.

Then add an Edge Split modifier to the object.

The extra edge is now gone.


What is this extra geometry which cannot be edited in edit mode?

That 'extra' geometry seems to be created by the modifier stack so can't be selected in edit mode unless you apply the modifiers.

I would dare say it actually looks like a face with a wrong normal producing that artifact with a solidify modifier. If that's the case in edit mode select all your geometry and press Ctrl+N to Unify Normals and see if the artifact is gone.

Edit

Your problem are overlapping extra faces, you probably created them accidentally by extruding your faces and inadvertently creating zero sized faces.

Switch to face selection mode by pressing Ctrl + Tab, select and erase the extra zero sized faces by pressing X, then select all by pressing A.
After remove doubles by  access the Specials menu (W) > Remove Doubles et voilá mesh clean.


How can I get a stereo cameras volume and parameters?

The code in properties_data_camera.py can give you clues to most of the camera properties.

The volume options for the 3DView are displayed with code in space_view3d.py and use properties within the 3DView data eg. context.space_data.show_stereo_3d_volume.

The volume pyramid drawn for this option is based on a pyramid created from the camera location/rotation, using cam.lens which is shown to the user as focal length and cam.sensor_width (sensor size). The cam.clip_start and cam.clip_end define where the top and bottom of this pyramid are. The actual c-code that does the drawing can be found in drawobject.c

The location of the convergence plane is based on stereo.convergence_distance and looks to use the same calculations as clip_start with the outer edges based on the same volume pyramid.


Array modifier does strange things with mesh

It is very likely that merge distance is set too high. Array modifier behaves unexpectedly when the merge distance is larger than the object. Try applying the scale with Ctrl+A and setting the merge distance to a reasonable value. That should be all that's need to fix this.

Modifier order does change the result, however they should work correctly in any order.


Blender is not an image viewer application, you can't just use Blender to directly open image files from File > Open

You also can't just "view" images directly nor can you expect it to just open a spherical image as display it as a panorama viewer.

You can however use the builtin UV Image Editor to view regular images and use a workaround to view spherical 360 panoramas.

Starting a few versions ago Blender added support for world preview as viewport background. As a workaround you can use that as sort of a spherical image viewer. It will be obscured by the 3D View interface (grids, cursor and objects), but serves as a basic viewer.

With Cycles as your current render engine create a new World datablock from the Properties Window. Add a new Environment texture to its color input.

Pick the Open image button and browse your file system to the desired image file (JPG, PNG, or HDR formats).

Pick the image then in the Properties Shelf over the 3D View (N key) under View tab activate the World Background option if disabled.

You should now be able to use the 3D Viewport as a basic spherical 360 panorama viewer.


You'll have to utilize more bones and constraints for this
I'm not sure if this is exactly what you are looking for but maybe it can be a starting point.

The toe bones have a "Locked To" constraint which are tracking the "track_to" bone, I set up a foot bone which is what you will animate and the "track_to" bone will follow the foot bone along the ground which has "Copy Location" constraint on it. Download the Blend if you want to deconstruct the setup.

Bonus Gif


There are still possible solutions by using some node-based animation addons like Animation nodes and MotionTool. It is hard to cover enough information here on how to use them, but you can learn them from many places, and they are not so hard to learn at all (I'll try cover the basic usage if really requested).

Now let's take a simple case. Assuming you want to render the object(s) during frame 1 to 10, not render during frame 11 to 15, then render again from frame 16, we can use them to do so:

Setup for Animation Nodes:

Setup for MotionTool:

P.S.: You can still insert keyframes for buttons and values on those nodes, which may further simplify the setups, but the animation data haven't been exposed to any editors, which makes it less convenient to control, and not currently recommended.


Entered weird mode, tab switch between "Edit" and "Edit Strokes"

this link might help

https://docs.blender.org/manual/de/dev/interface/grease_pencil/stroke_edit.html

if you want to get out of stroke edit mode try pressing d-tab


How can I hide hidden topology with a hologram shader?

Cycles
Light Path > Transparent Depth

Eevee
Material Properties > Settings > Blend Mode > Alpha Blend
Show Backface > OFF


I expect the skin modifier can a create the armature that you are after.

If you only want a rig for a portion of your mesh, duplicate the mesh an delete the excess parts.

Add a skin modifier. You may want to use Mark Root in edit mode with one vertex selected at the end of your mesh, this can prevent extra bones and keep the bones facing in the same direction.

Click the Create Armature button in the skin modifier.

You can then delete the skin modifier, or the duplicate mesh if you duplicated it to start with and you are left with an armature matching the edges of your mesh. The new armature has the display set to stick which you can change to octahedral in the armature settings.


Without using an armature you can use parenting and constraints.

Starting with two cylinders, add two empties. The empties should be located at opposing ends of each cylinder.
Select a cylinder then Shift select the matching empty and parent them with ⎈ CtrlP -> Object. Repeat for other cylinder and empty.
Select a cylinder and add a TrackTo constraint. Set the target to be the empty of the opposing piston and set the axis to suit. Repeat for other cylinder.

Now as you move one of the empties the two pistons will always point towards each other. If you position one of the empties at the outer edge of a disc and parent the empty to the disc it will rotate around with it and the cylinders will follow.

Here is a sample file to look at.


Why does this material change colors throughout the animation?

The reason why the tunnel gets brighter and darker is because of the point lights that you've scattered across the tunnel. Areas closer to the lights (orange dots shown below) are brighter.

You can fix that by moving the lights with the camera instead of fixing the lights into a single spot. Delete all but two of the lights and parent them to the camera (yellow dot). It doesn't really move the lights perfectly along the middle of the tunnel, but you could always animate them manually to fix that.


There are many ways to fix this.
If you select an object in your project, you can do do View > Frame Selected to center your viewport on that object.
Alternatively, View > Frame All Will move your viewport to be centered looking at all the objects in your scene.


Extrude faces seems to move faces and extrude outer edges

The hidden rules of Blender's operators can become so familiar that you don't notice them any more, and work round them / with them without noticing them. This is an example, for me, so it's interesting to have a look.

Trying to reduce it to the minimum case, Blender seems to use quite a simplistic rule to avoid the creation of internal faces when extruding regions, while still providing expected behavior when extruding simple, isolated shapes.

In this example, we start with two squares. One has a connected face extending one side.

The pink and blue faces were extruded downwards in separate operations. The pink extrusion left a face behind, the blue one didn't. This suggests Blender's rule is to duplicate a region of faces only if none of the edges surrounding it are shared  by another face.
Sure enough, the green faces were extruded in one operation. Still, the extrusion didn't leave a face behind, even in the isolated region. So the rule seems to be not to duplicate faces if any bounding edge of the selection is shared. (This applies even if you try setting the extrude to 'Individual Faces')

So it's not something funny you've done. Your best route to where you want to go is probably to select the edges on the outside perimeter of your base, EZ them downward, and F fill the bottom end. Or, work in one direction, from the bottom up,I insetting on the way.


Make Boolean not affected by subsurf modifier

Modifiers are calculated from top to bottom in what is called a Stack.

Changing the order of the modifiers in the stack will yield different results:

Boolean before Subsurf:

Boolean after Subsurf:

Animating the size of the cube:


What is the panel that appears after Scale operation and what is the command to display it independently?

The panel is called "Redo Last"

It's always in the tool shelf T of the 3D-Editor or accessible as a popup with F6.

https://docs.blender.org/manual/en/dev/interface/undo_redo.html


He has an old version with dark skin. Since 2.8 version interface was redesigned and changed.


How to snap 2D cursor to key in graph editor

Use Key>Jump to keframe (or press Ctrl+G) to place the cursor on the selected keyframe.


Mesh looks edgy in object mode and smooth in sculpt mode

I solved the problem by exporting the mesh in a Wavefront format (obj).When I exported it I checked Selection only and unchecked everything else.Then in a new project I imported the obj file and it seems to behave normal now.


When you see a line like that between two keyframes it means that there is no change: the values for the keyframes are the same. The keyframe is duplicated.


in Game Logic, can Object A use Object B's sensor?

Maybe I'm reading this wrong, but, it looks like you just need to select both objects, and connect the sensor from objectB to a controller from objectA.


How to stop execution of a Python script without closing Blender too?

Maybe not too elegant, but it will stop the script in the middle and won't close Blender:

raise KeyboardInterrupt()


Be sure to be in Pose mode with your armature selected.

In the Dope Sheet Editor, select all the keys (A) and move them some frames to the right. (G25Enter for 25 frames = 1 second)

Go to frame 1, in the 3D View select all the bones, press Alt+R and Alt+G to reinitialize position and location. The rig should be in T pose now.

Select all the bones, in the 3D View press i to insert a key on location and rotation (LocRot).


Modeling smooth flat edges along the curve

The idea about subsurf modifier is that you use fewer well positioned vertices in your lowpoly mesh and let the modifier smooth inbetween. You have unneeded polygons at some spots that hinder the smoothing, and at other spots you don't have enough detail in your mesh.

Generally if you want a clean model you need to take more attention to topology. If you want to clean it (also for academic reasons) then search for "retopology", which is mostly used in creating a good lowpoly mesh for sculpted human faces.

You can also use sharp edges for more control about the subsurf modifier, very useful if you want some edges to stay unsmoothed without adding a lot of detail in the lowpoly mesh.


Why does my mesh have lots of square on it?

First, select the mesh. Then click on the Tools Tab, and under Shading click Smooth.  Another option would be to subdivide the mesh.

Edit:
Also, if you don't want the bright spots, go to Properties > Material and change the Specular Intensity to zero.


Parts of armature moving other parts of the model even though there's no weight paint there?

Try it with auto-normalize disabled.
But you have to be careful, as this could mess up your weights and you may need to normalize them again.

You can also try it with "Limit selection to visible" disabled.
This could help if you have overlapping meshes.


Blender crashed and now when I try to open the file still crash!

Press append,
look the scene up and append it, that will append everything into a new scene.
Before you do anything open a blender file tab, you delete the necessary objects from there.

Save the file and then switch from scene and hope it does not crash again


I think it would be better to use tesselated cylinder with Curve modifier, length of cylinder remains constant, just modify bezier shape.


Why does the File Browser's 'filepath' property include the blend file name once the file has been saved?

Thanks to all for the input. I am answering my own question.

I wanted to have in my AddOn a way to choose a folder containing some input files. It turns out that it was very easy using bpy.props StringProperty as panel property:

import_path: StringProperty(
        name = "Path",
        description = "Path to the folder containing the files to import",
        default = "",
        subtype = 'DIR_PATH'
        )

The DIR_PATH (or FILE_PATH, if expecting files) subtype is presenting a file system browser and retrieve the relative path, one just have to convert it to a absolute path in the operator:

bpy.path.abspath(self.import_path)

see here


When I asked to simplify the blend, I ment to keep one example of cloth, only bricks that directly collide with cloth, there is no need to keep brick with a huge amount of vertices for this issue, so Decimate modifier could be applied (it slows down calculation any time you run simulation). You have also set Fake User for many objects. When deleted from a scene, they are still a part of file. To get rid of them you have to go into Outliner > Ophan Data > uncheck all of them and hit Purge. If objects are still there you can select them manually with Shift and with right-click choose Delet. Like that you can go from 184 MB to just 4 MB for a blend you could share with us (saved with compression enabled).

Collision
If you set Rigid Body just for colision with cloth (and you don't plan to destroy a wall later), it would not work.
You have to enable Collision that you can find above Cloth Simulation.

Tips:

If you plan just collide a cloth with a wall I would suggest you to use a simple plane (subdivided a few times), that is much faster for collision calculation.
To deactivate Rigid Body sim for all bricks at once - go to Scene Properties > Rigid Body World > Remove ... (it will remove all rigid body in a scene).
Quite annoying is cached cloth sim, that is not always updated when you change parametr. To recalculate sim with actual setup, I know only one way - deactivate&activate monitor icon on Cloth button.
To apply modifier for all selected objects, search for Convert to Mesh. Sounds weird, right? It is a mesh already, but this operator apply all transformations at once for all selected.


Use python to make Box A smaller than Box B by fixed number?

context.object is also part of the context.selected_objects collection.

So here's what you can do:

import bpy
context = bpy.context

objs = [o for o in context.selected_objects if o != context.object]
for o in objs:

    x = context.object.dimensions.x

    y = context.object.dimensions.y

    z = context.object.dimensions.z

    o.dimensions = [x,y,z]

    o.location = context.object.location


What is the fastest way to merge similar uv islands

You can use UV Align\Distribute addon which will do what you want.

Here is how to use it: https://www.youtube.com/watch?v=clgrf0DUvso


Appending with bpy.data.libraries.load and drivers

The following code does the trick:

import bpy

# prepare files list for bpy.ops.wm.append(..)
files = []
with bpy.data.libraries.load("path/to/test.blend") as (data_from, data_to):
    for name in data_from.objects:
        files.append({'name': name})

bpy.ops.wm.append(directory="path/to/test.blend"+"/Object/", files=files)


This work

Line command

blender -b file.blend -P file.py -- "param1" "param2"

file.py

for i in range(6, len(sys.argv)):
    print(sys.argv[i])


You can try to use offset (bevel, extrude area ...) or to look for a font similar that does it, but I think the result will have to be edited a lot anyway for direction, points etc.

If you want to use this as paint/mask for a writing effect, I would do it this way:

grease pencil, manual place the strokes in order and direction that is convenient. (I doubt that you can actually get that too out of a font/offset)

I think is the most controllable way.. and grease pencil is kinda made for animated strokes

I use poly for convenience, may further use convert/bezier or so, you'll have to test your way
convert to curve with lots of options
use curve with options, with dyna paint or use it with addons (btrace, animation nodes etc) to generate your Alpha/mask...
if the text is very, very long (many lines) may want to make these into a blender font and then convert again to curves. But the process is worth only if you will use this template many times, for lot of text, imho.

An example. Note that for tracing, my path is not quite following your proposal, but more the way the paint will go.

PS: I post this as per comment where you say you use it to trace the text. Maybe that should be in the question too.


this, and .rayCast() should set you right

vector.reflect(hitNormal)
http://www.tutorialsforblender3d.com/GameModule/MathutilsModule_5_4.html


How do you scale eye texture using armatures?

You may do it using drivers. You can set the shapekey's transformation to be driven by the bone's scale as pictured below.

First select the eyeball and add a new shapekey being in Object Mode. Next enter the Edit Mode, set the shapekey's value to 1.000 (with the apply shapekeys in edit mode button enabled) and edit your mesh as you like (in my case I've decreased the pupil's size).

You may set the Min shapekey's value to -1.000, so Blender may create the opposite transformations (pupil's size enlargement) automatically for you

Now being in Object Mode add the single bone and place it in front of the eyeball (name it e.g. eye_pupil).

Now select the eyeball, go to the Shape Keys panel, hover the cursor over the newly created shapekey's value (near it's name), press RMB and choose Add Driver.

Next open the Graph Editor and set it's mode to Drivers. Select the shapekey's name on the left, open the properties shelf (N) and set the settings there as pictured below (you want the shapekey value to be driven by the local Scale value of the previously created eye_pupil bone using the Transform Channel).

You may also add a generator modifier to set the ranges of the driven values (but it's not neccessary).

Finally you'll have to update dependencies (just click the button pictured below).

NOTE: My answer shows how to animate the pupil only as I have the ready model which uses this kind of animation only. The video you provided shows the animation of the iris with pupil, but with the method pictured above you'll be able to do it in the same manner.


The edge disappeared in object mode, but show up in edit mode

Blender does hide some edges in object mode in an attempt to not show unnecessary edges in wireframe view or with the wire option enabled, however as you can see its not always perfect. The simple solution is to go to the Object data panel and under display check 'Draw all edges'.


Here's one possible way:

Start with a round cube (quadsphere preset) from Add Mesh Extra
Objects add-on.

Delete top half of the object

Select groups of faces that will make up the legs

Change pivot point to individual origins with
Ctrl+. (period)

Run loop tools circle operator on the selected faces W >L > C

Extrude by nomals with Alt+E then adjust geometry as you need.


Select and fill face in UV Editor using Fill brush

No, there is not at the moment a way to do this without using the 3d view. You can use the edit mode in the 3d view and the UV Image Editor to make a selection, and then switch to texture paint mode in the 3d view with Face Select Masking turned on, Fill tool there in the 3d view and see the update in the UV Image Editor.


How to texture paint a mesh while it's transparent?

If it's just about seeing a reference image, which you loaded in as a Background image to a view, you can set the display of it to 'Front'. It's the Button under the 'Opacity' slider, by default it is set to 'Back':


How to change text color from red to white?

Go to top view (Numpad7) In edit mode select the A & P text with box select. In the material tab add new color and change color white (fffff) and assign the material to the mesh.


How to pop up this command" object.modifier_add"

The string you type in the shortcut configuration screen is not Python code. It just happens to look somewhat similar to it. To run the operator as Python code, prefix it with bpy.ops, so bpy.ops.object.modifier_add().

However, it's better to not use operators at all, and use a regular Python function instead:

bpy.context.active_object.modifiers.new('operatorname', 'BEVEL')

See the documentation for more info on all the operator type names. This function returns the new modifier, so you can set properties on it directly.


Animating active object issue in motion tracking project

“Animated” is checked. The sphere will follow its animated coordinates when this is checked. If it becomes checked after the sphere has physic-ed around, it will snap back to those coordinates.


How do I remove light from Material Preview Shading in the 3D viewport?

By default Material Preview Shading uses a different environment and lighting than the Rendered Shading so it ignores the world settings.
In the Options tab, you can choose to use scene world and lighting .


Imported openVDB sequence from another scene moves around randomly

It has to do with the adaptive domain and how to origin is imported


Blender Cloth, Single object with two meshes, wanting to keep them joined for first few frames of cloth physics

Hook modifier could do it, but there is perhaps a way to do it through simulation which would give better results.


How to make a line an exact size without changing the size of the whole object

In your pictured example I would select the end vertex, grab it and use vertex snapping to put it on top of the next vertex to the right.

Without changing my selection I would now grab it again, lock movement to the Y axis and type in how long I want it to be (you may need to use a negative value if you are moving towards -Y).


How to subsurf this wing without adding vertices to its profile (only to the curvature)

Beveling Edge Loop:

Choose Edge Select mode and select desired Edge Loops (like you have in your screenshot now) then hit Ctrl+B to Bevel, you can set amount of Edge Loops by hand (mouse scroll and move) or just by tweaking values in Tools Panel or by pressing F6.

Loft with LoopTools:

This method will allow you to add the same number of Loops between existing ones. You need to turn on LoopTools addon in User Preference menu.

Select all Edges between Loops, delete them, then select remaining Edge Loops, hit W > LoopTools > Loft and change values accordingly.

Sadly there is not (or I'm not aware of it) any automatic method to give same space between all Edge Loops given that there is different space with existing ones. You can just put same amount of cuts. As a workaround you can make two things. First one is kind a eye-balling, so it's not perfect.

Spacing Manually by Loop Cuts:

In this method you will need to place Loop Cuts (Ctrl+R > MouseScroll) manually and eye-balling number of cuts. It could give pretty nice result with a little of practice.

Dissolving and adding new cuts:

This one is a last option, this will give even spacing but will not preserve main shape and you will need to manually move Edge Loops with Proportional Editing turned on.

Select existing Edge Loops, Dissolve Edges, add Loop Cuts, move new Edge Loops with Proportional Editing turned on (MouseScroll to control influance).


How do I save an edited texture to a file from within Blender?

From the Image Editor, press f3 to save the image to a desired location and name (save as) and you can press Shift+S to save the image over that previously saved one. (Save)


Random color in materials to not change when I copy the objects

As Carlo's comment suggested, you could bake the color onto a texture.

Activate the Texture Atlas Addon.
Add an empty image texture.
Select all objects and unwrap them using the texture atlas addon.See the texture atlas documentation for more instructions on this addons usage.
Bake the Diffuse Color only using very few render samples!
Replace the Object Info random output with the image textures output.


I'm getting the skin/cloth overlap. What i'm doing wrong?

You are most likely getting this problem because the body and the clothes have different topology and weight values for deformation. Open the clothes in weight paint mode, then add weight on parts where the body is sticking out.


How can I get particles to collide with objects?

If you would like to form a pyramid from particles I recommend that you use keyed physics.

Here are my particle settings

Pyramid's particle settings called Initial

Cube's particle settings called Main

Start frame: 1, end frame:100, lifetime: 250


How to make an animation so that it is smooth and plays at one speed?

One possible solution to the question (before it was updated with a use-case):

You could build curves into the corners of a trajectory path, like:

Tighter corners will result in more jumpy (sudden, unrealistic) movement.

Here I start out with a Mesh Object, then use Ctrl+Shift+B to fillet the corners, then in Edit Mode use Alt+C and convert the mesh to a Curve Object.

Then Add a Follow Path constraint, and press Animate Path, then press Play to see what that looks like.

Sometimes It can be more convenient to see the path it will be on, rather than key-framing it.


probabilistic termination of transparent bounces

From Blender Manual > Light Paths > Bounce Control

Light paths are terminated probabilistically when specifying a minimum
number of light bounces lower than the maximum. In that case, paths
longer than minimum will be randomly stopped when they are expected to
contribute less light to the image. This will still converge to the same image, but renders faster while possibly being noisier.

Related thread on BlenderArtists.org


How to add same texture to multiple objects

Apply texture to one of the cubes, then select all the cubes and the textured cube as last, then use Ctrl+L shortcut and select Object Data from the menu.


It can be hard to learn at first but you need to take long and sometimes frustrating baby steps. If possible, try to understand both 2.79b while it is still available for download and also 2.8. 2.8 is still in beta and brand new, as of about a month or 2 ago.

Most tutorials are for Blender 2.7x so I would advise to start off there and use tutorials such as https://www.youtube.com/watch?v=kes2qmijy7w Blender fundamentals. Blender Guru is also a good source for medium to higher level modelling and has just released a video on the new 2.8 layout which I suggest watching Watch both this one, https://www.youtube.com/watch?v=lPVpg4_POww, which is the Blender Guru new layout video, and the first link which is a Blender 2.79b video of a similar nature to gather how different the versions are, which is why I suggested to learn 2.79b since there are so many videos available for it. Start small and learn all the functions first. Remember that Blender engine has been removed in favour of the new Eevee rendering engine so as much as possible try to learn in cycles, but couldn't hurt to learn both the blender engine and eevee engine layouts.

Since 2.8 is still new there won't be as many answers and the layout has dramatically changed so it would be hard for a beginner to watch tutorials done in a 2.7x version and follow along in 2.8, which is why I suggest learning 2.79b first. Once you have an understanding of 2.79b then you can transfer allot of skills easily over to 2.8 by finding the new locations of the tools and menus. Good luck with it.


Script to replace all materials linked to the a given texture

Ok, the following script does a bit more. See comments - disable "renameUVMaps" if you don't plan to join the meshes. Useful to rename the UV of identical textures so that mapping data is kept active.

import bpy

# Options
renameUVMaps = 1

# 1. Get the "active texture name"
activeObject = bpy.context.object
activeUVMap = activeObject.data.uv_layers[0]
activeMaterial = activeObject.active_material
activeTexture = activeMaterial.node_tree.nodes["Image Texture"]
targetImageFilename = activeTexture.image.name

print('Material %(materialName)s will now replace materials using texture %(textureName)s' % { 'textureName' : targetImageFilename, 'materialName' : activeMaterial.name})

# 2. Loop through scene objects and replace materials with the selected one (when the texture file name matches)
for obj in bpy.context.scene.objects :

    # 2.1 Re-assign material
    for slot in obj.material_slots :

        thatMaterial = slot.material
        thatTexture = thatMaterial.node_tree.nodes["Image Texture"]
        thatImageFilename = thatTexture.image.name

        if targetImageFilename == thatImageFilename :

            if activeMaterial != thatMaterial :
                print('Obj %(objName)s -> replacing %(materialName)s in slot' % { 'objName' : obj.name, 'materialName' : thatMaterial.name })
                slot.material = activeMaterial

            # 2.2 Rename UV Maps for joining
            if renameUVMaps == 1 :
                if hasattr(obj.data, 'uv_layers'):
                    layers = obj.data.uv_layers
                    layerCount = len(layers)

                    if layerCount > 1 :
                        print('!!! Obj %(objName)s -> has more than 1 UV layer' % { 'objName' : obj.name })

                    if layerCount == 1 :
                        uvLayer = layers[0]
                        if uvLayer.name != activeUVMap.name :
                            print('Obj %(objName)s -> renaming UV layer to %(targetUVMapName)s (was %(previousName)s)' % { 'objName' : obj.name, 'targetUVMapName' : activeUVMap.name, 'previousName' : uvLayer.name })
                            uvLayer.name = activeUVMap.name

print('Done.')


Just assign a fully transparent material to that part of the mesh.


What is the 2.8 shortcut for "Operator Search" on Mac?

You have to hold down function (fn) then hit f3.


console warning: "Too many lights in the scene !!!"

For questions like this please indicate what render engine you are using. Eevee has a limit of 128 lights in a scene.
Read:
https://docs.blender.org/manual/en/latest/render/eevee/limitations.html
Also, for simulated LED arrays you might want to consider a single texture as part of an emission shader.
How to give an image or video a TV screen effect?
and
How to control many tiny lights


Does any one know how to fix Hidden Vertices With Subsurf modifier?

This is a setting within the subdivision surface modifier. It currently displays the vertices as they are. If you want them to be displayed as if they are changed by the modifier you just have to turn on 'On cage' in the subsurf modifier:
Off:

On:

Hope this helps!


Specials Menu/Deleting Doubles in Edit Mode

It's now called merge by distance under the mesh, cleanup. If you right click it once you see it in the menu, you can add it to a favorites list that comes up when you type Q and select from that pop up each time quickly.


judging from your outliner you might have a hidden mesh/object.

Try Alt+ H


saved blender file doesn't play any audio or video

SOLVED all I had to do is move my blender file back to where I saved it. I recently moved the file to another folder and just by moving it back to the original folder it worked.


The source for the displacement map in this case has to be an image or procedural texture, not the model itself. One way to do what you want would be to get or create tileable plaster texture first (look for "tile plaster texture bump" on a search engine), then create a material just for the walls, assign it and unwrapp the walls as you see fit.


How can I make the neck of this desk light?

Modeling

Create a bezier curve tracing the neck of the lamp. Model a small part of the neck and array it using the bezier curve as a Fit Type. This will repeat the part till it fits the length of the curve.

Then using Curve Deform modifier, deform the output over the curve.

Now scale the object and apply the scale to get the required amount of repetitions.

Procedural Shading

If you want to implement the bumps in shading stage. Solidify the curve and and enable Use UV For Mapping.

Then for the material, use the $x$ component of the UV to compute strips like pattern where the value $20$ controls the number of repetitions, $0.17$ controls the width of engraving and $0.2$ controls the relative slope of the transition.

You can now use this as bump of displacement for the material.


Color is not applied when drawing fonts in BGE with blf and bgl

The problem was lying in the Shading settings of Blender. By default, the shading is set to Multitexture, which makes the blf text be only black. If you set the shader to GLSL (see picture below), the colors behave exactly as you would expect them according to the python script that is in my example.


Ah got it, the normals were inside after extrude, didnt see it for I was in eevee render and no normals overlay activated:-)


To use the clone brush :

Select the clone brush in the paint tools
Ctrl+LMB to set the origin of what to clone from (the 3D cursor is set at this origin)
Then simply paint on the target position

Painting with a strength set to 1 is often better, but it depends on what you want.

If you want to clone from a picture that is not in the current model, you may need to set this picture on another mesh then join the two meshes, as this tool does not handle to clone parts that are outside of the painted mesh.


How can I freestyle render outlines but remove the object itself?

It looks as though you want to make the walls transparent to the floor, but not to themselves. (They're occluding their own back edges)
For maximum flexibility, you can set Cycles to render a separate Freestyle-only pass on transparent film ..

EDIT: 2.91 .. I think the filter selection is now negative: what's required is to uncheck all filter options, with Freestyle switched on.

.. link your walls and floors to separate Collections ... here, named 'Solid' and 'Transparent'.

Create a View Layer for each Collection. Deactivate unwanted collections in the corresponding layers as shown above. Each layer gets its own Freestyle Line Sets, which can be set to pick up Visible, Freestyle-Marked edges. Then you don't have to worry about transparency in the Line Sets themselves, because you're using the Compositor to overlay them:

This will increase rendering time a little (is this for still images?) but you can set the samples down in Cycles quite a way, 32 seems to give adequate anti-aliasing on the lines.


How to obtain selected UV pairs on same edge in Python?

You're almost there. I've taken the liberty to remove the construction of unnecessary lists, and used generators in their place.

The most important change is indeed in that if statement. Instead of using the link_loops list (which can be of arbitrary length), it's better to only use link_loop_next. Since you loop over all selected edges anyway, it's enough to look at the 'next' edge only.

import bpy, bmesh

obj = bpy.context.active_object
bm = bmesh.from_edit_mesh(obj.data)
uv_layer = bm.loops.layers.uv.verify()
sel_faces = (f for f in bm.faces if f.select)

def find_loops():
    """Generator, yields loops of selected mesh faces"""

    for f in sel_faces:
        for l in f.loops:
            yield l

def find_selected_loops():
    """Generator, yields loops that are selected in UV editor"""

    for l in find_loops():
        if l[uv_layer].select and l.link_loop_next[uv_layer].select:
            yield l

# Show the coordinates of selected loops. Note that loops are printed
# twice, once for the (A -> B) edge, and once for the (B -> A) edge.
print()
for l in find_selected_loops():
    print(l.vert.co, ' -> ', l.link_loop_next.vert.co)

If you want to remove the distinction between (A -> B) and (B -> A) loops, you could extend the find_selected_loops() generator so that it stores the tuples (l.vert, l.link_loop_next.vert) in a set, and only yield those edges whose (l.link_loop_next.vert, l.vert) are not in that set.


Object in different scene gets renamed without any warning

No, this is how blender operates and also one of it's design flaws and known limitations. The software is not very forgiving, you either need to know what you are doing or learn by mistakes - it doesn't warn the user much, every button is basically a nuclear missile launcher (though recently a prompt to quit was added).

What you can do as a workaround is to have a watcher running on background (effectively slowing your blender) to notify you when a name is changed:

Execute a python function whenever the user interacts with the program

You can alter that script to check anything you want (even all the scenes for changes), as it is now it prints name changes of one hadrcoded object into the system console.


Shading issue when adding Subdivision Modifier

Looks originally like "Normal" problem. this post will give you an idea about it. it happens a lot when models are extruded.

Blender How to Recalculate Normals


This is a classic weight issue. The vertices that aren't moving correctly are either weighted to the wrong bone, aren't weighted to a bone at all, or aren't weighted enough to the right bone.

Vertices follow the movement of the bone they're assigned to, but they can be assigned to only follow a percentage of a given bone's movement. For example, if you assign a vertex to a bone at 50% (or 0.5) and then rotate the bone 90 degrees, the vertex will only follow half of that movement... 45 degrees. Furthermore, you can assign a vertex to more than one bone. For example, you might assign a vertex on the knee to 50% on the lower leg and 50% on the upper leg so that smooths between both of them.

It looks to me like you have a handful of vertices on the (left?) leg that are not assigned to the bone going back to the left. Consequently, the bone moves to the left, but the vertices don't follow. A similar thing is probably happening with the ones on the right. Note: "not assigned to" might also mean "assigned to a different bone."

Interesting note: it's possible (depending on your Blender settings) to have a vertex with more than 100% total influence. Unless you have "normalize all" turned on, all the weights will get added together and do weird things.


Is it possible to have a Material input node in the Cycles Renderer?

All the given answers in the comments work correctly and as I expected.

I finally ended up using the Node Groups.


House architecture- How to extrude or move a face along an edge

In 2.8,  create a Custom Orientation from one of the sloping edges of your roof, by selecting the edge before hitting '+' in the header's Transform Orientations dropdown.

Then, GY will constrain translations to the direction of the slope, if the new orientation is in use. (Which it will be, by default, after creation.)

Also, following @AnthoJack's helpful answer here, it might suit your workflow better, (having set your cursor to 'Surface Project' and 'Geometry') to set your standard Transform Orientation to 'Cursor' for longer periods. Then you can effectively set up temporary Custom Orientations from faces of existing geometry by simply dragging the cursor over them.

(In 2.79, it's: Select the edge: hit CtrlAltSpace with 'Use After Creation' checked: use GYY)


What is the relation between the scale nodes that includes the pixlate node?

You need one scale before the Pixelate node, and one after it.

In my nodes, I scale the image down to one tenth of its size (the first scale node), pixelate it (the Pixelate node), then scale it back up to its original size, with the second Scale node.

The relation of the scale values is the mathematical inverse. Say you scaled it down by .5, that is just multiplying it by .5, or dividing by 2. So to scale it back up to the same size you need to multiply it by 2.

Here is an example table of the values. The first scale value and then the second scale value.

.1      10
.2      5
.3      3.333`
.4      2.5
.5      2
.6      1.6667`
.7      1.42857
.8      1.25
.9      1.111`

Note that the strongest pixelated effect is at the top of the table, and the weakest is at the bottom.


Light without any Light/Environnement with EEVEE

I experienced the same results when I tried to create an empty night scene without any light.
Even without any light in the scene, the "False Color" View Transforms showed that the polygons were lit in EEVEE... However, the render in Cycles was completely black.
I solved my issue by pressing "Bake Indirect Lighting" then "Delete Lighting Cache" and everything became black again in EEVEE and Cycles.


In Texture Paint mode, is there a way to paint a desired color over another color in ONE click/stroke?

You can mainly play with the strength of the brush and with the brush shape itself :


My properties panel is horizontal, how do I turn it back to vertical?

Rightclick in the panel, and pick Vertical


The line is being caused by a "crease" which is the result of 2 edges being too close together on a curved surface. Although the inner edge is necessary for the geometry of the "top part", it is interfering with your mesh where the geometry is not needed.
One thing you could do is grab a section of the inner edge in the middle of each "gap" and edge slide (G + G) it so it pulls the second edge away from the first where they don't need to be close together. There may still be some artifacts in the corners though (circled in yellow), and if this ends up looking too incorrect, you may be best going with 2 separate pieces.


How do you use a multiple leaf texture file on a sapling curve tree?

Multiple objects can use different parts of the same material using UV mapping. In this example, The original UVs of the image plane are cut automatically when using the Knife tool. Split the edges and separate the loose parts to create multiple objects. Note the single material used.

That same material can also use the same UVs for applying alpha, normals etc...

Note: the "Import Image as Plane" is an Addon.


First, add a UV Sphere to your scene. Now go into edit mode, make sure you are in Face select mode (press Ctrl + Tab and select Face) and press Ctrl+B. Make the resulting edges as large as desired. Now press Ctrl+I to invert the selection and then press Delete > Faces.

Now go into edit mode and select all by pressing A, and then W > Subdivide Smooth and change the subdivisions up or down as desired.

Now add a Solidify Modifier to your object to add some depth. You may also want to add a Bevel modifier while you are at it.

You should now have a nice smooth wireframe:


How to re-organise messy uvs on texture image

It won't get any better than that. This mesh is complex with a lot of small details. So either UVs will be stretched either they will be disjointed. In this case, it is usual to paint directly on a mesh and not on the UV islands.

There are some solutions. Paid or not. This particular one is not ready, but it is about Blender: https://www.youtube.com/watch?v=PLUoLQUK3-s Usually this stuff is done manually, which won't pay off in this case. I suggest to leave it as it is.


Cylinder with varied light power intensity along the axis

You could try something like this.

All I did was take a Wave Texture on the vertical (Y) axis, stretched it out a bit and colored it with a ColorRamp to make light and dark (red) areas. I overemphasized them a bit because sometimes subtle differences don't show up well in screenshots.
All I did after that was take another Wave Texture, set to run on the Z axis (Horizontal), scaled it down so it was only one (visible) band, distorted it a little, and then used that "warped gradient ring" as a constraint for the color, so it looks less like it's on a flat surface, and more in a neon tube. I did this by multiplying it with the color in a MixRGB node. I finally ran it through an emission shader, in keeping it being with a light source, and I turned on "bloom" under the render properties tab to make it glow. The end result (against a black background) looks like this:

FYI - there are white patches on both sides, I only shot from one angle. You can control the amount and the size of the patches using any combination of the Mapping Node, the Scale of the Wave Texture, and by moving the "Needles" of the ColorRamp.


Strongly suspect symmetry across x or y axis is engaged Martin! Many fun parameters located at bottom of 'Tools' tab of toolbox (shortcut T, or can be pulled out from tiny "+" at left edge of main 3d viewport).  :-)


Cannot Save Blend File Says, "Cannot open file filename.blend@ for writing: Too many open files"

So I had no choice but to force close Blender and lost hours of productive work because of this problem.

I still have no idea as to how this problem even occurred but a good reminder to always save your work constantly. Otherwise, you'll lose hours of productive time.


Under User Preferences > 3D Viewport > Display you can control the 3D Viewport Axis gizmo display type.

Three options are available: Interactive Navigation (the default), Simple, or Off.


Mirror object diagonally (or Symmetry about origin), i.e. excusively in X+Y

Point Reflection.
As pointed out by @RobinBetts can achieve point reflection by using the array modifier, with offset object and the offset objects scale inverted.

In this case have constrained the offset empty's location to the inverse of the original.
Rotate the Mirror Object.
If the object already has symmetry in X & Y

The mirror object set via the modifier acts like the mirror plane. Rotating the object, rotates the reflection.
In example above, mirroring in $X$ axis, which is normal to the mirror plane, and at the location of the empty.  Any 3d plane can be defined by a point in space, and the normal vector to the plane
Similarly could mirror in $Y$ and rotate empty 45 to achieve same result.


It's not clear from your question whether you installed Blender via the command line or by downloading the package.

I'm guessing you installed via the command line as you are encountering dependency issues.

Try downloading the latest release from blender.org, then just double click the executable icon 'blender' in the 'blender-2.7*' folder, or navigate to that directory and from the command line run: ./blender

To reiterate the comment above, you shouldn't be running this as root.


BI "Front/Back" vs Cycles "Facing" - Angle of Incidence in Blender Internal

Do these perform the same function and just have different names, or are they doing something different?

No, they don't. They perform something different:

Facing output from Cycles Layer Weight node gives angle of incidence. You can read about this node and how it compares to the Fresnel node here: Relation between Fresnel IOR and Layerweight blend?

You can make it from scratch in Blender Internal node material like this:

Front/Back output from BI Geometry node is the same as Backfacing output from Cycles Geometry node and gives a binary true/false (1/0) if a face is oriented to the camera with it's normal or not.


Forcefield as collider with dynamic hair

Well it does work afterall when I increase the strength to a much higher value like 500 or more.

As you can see I got another issue then though with the distance, which I will ask in a new post.


You need to have an active face. This is a way to give an indication to Blender in order to control which faces will be kept selected:

If no face is active, you obtain the message mentioned in your question.


How do you extrude a shape without outer faces and edges?

This feature has just been added to Blender.
It will be available from version 2.90(https://builder.blender.org/download/).
It's called "Extrude Manifold" and is located in the toolbox T, under the "Extrude" dropdown, Or by pressing Alt+E.

↑ Here I'm using Face select mode (3) but it works in vertex select too


You can press A to select all the objects then deselect camera and lamp, after that press Shift+C to set your 3d cursor to the center, and press Shift+S then Selection to Cursor (Offset)
This should place your objects in the center of your 3d scene.


Adding materials to more than one object

It's possible link the materials on a selection of objects to a single "active" object.

Add an material to an object:

Select all of the objects you want the material on, then select the object from step 1 (it's important that you select that object last; it needs to be the active object). Hit CTRL+L and select Materials


How to align an object so one of its faces are axis-aligned? (make an object upright for eg)

Blender doesn't have a tool built-in to perform this operation currently.

If you would write your own tool,
a method you can use to achieve this using Python.

Define the source vector (face normal in this case).
Define the destination vector (the axis vector).
Use the rotation between these vectors to define a 3D rotation(see Vector.rotation_difference).
Then rotate your object by this.

This example uses the normal of the first face, assumes object

import bpy
from mathutils import Matrix, Vector

obj = bpy.context.object
matrix_orig = obj.matrix_world.copy()

# for this example just pick the first face.
axis_src = matrix_orig.to_3x3() * obj.data.polygons[0].normal
# z-axis, could be any direction
axis_dst = Vector((0, 0, 1))

matrix_rotate = matrix_orig.to_3x3()
matrix_rotate = matrix_rotate * axis_src.rotation_difference(axis_dst).to_matrix()
matrix_translation = Matrix.Translation(matrix_orig.to_translation())

obj.matrix_world = matrix_translation * matrix_rotate.to_4x4()


Select the External mode on the script node and set the filepath to your .osl source file or a compiled .oso file. Or, if you put your shaders under the shader search path (see below), you can simply specify the filename.

From the documentation:

  The External mode can be used to specify a .osl file from a drive, and
  this will then be automatically compiled into a .oso file in the same
  directory. It is also possible to specify a path to a .oso file, which
  will then be used directly, with compilation done manually by the
  user. The third option is to specify just the module name, which will
  be looked up in the shader search path.

  The shader search path is located in the same place as the scripts or
  configuration path, under:

  Linux

 $HOME/.config/blender/2.79/shaders/

  MS-Windows

C:\Users\$user\AppData\Roaming\Blender Foundation\Blender\2.79\shaders\

  macOS

/Users/$USER/Library/Application Support/Blender/2.79/shaders/


Are you using the denoiser node in the compositor? I’ve had something similar happen using the denoiser and transparent backgrounds.


Freestyle rendering out of sync with pose 2.8

It turns out that I was using a slightly older (by about a month) version of 2.8.  Updating to the latest version fixed my issue.