Animation Nodes - Pressure Arrows / Scaling, Rotating and Changing color along surface Original Question (Edit below):



I want to make a "fluid pressure" representation. That image was my "first" try, but I can't rotate or move the matrix. Why do I want to move it?

I want a "room" made of "pressure representation" walls. So, If I can copy the matrix, I could rotate it. I could, even, animate as a child of an object.

But the real effect I want is in this tutorial: https://www.youtube.com/watch?v=Vxc4P0YI2rI&amp;t=493s

Because in this way, I could have "pressure arrows" for all the volume, no matter the shape/surface form.

But instead the instanced/matrix/particles objects rotating...


Scaling (with a minium visible size to something larger but no huge)
Rotating (45º because the effector or direction effector).
Changing color (Blue neutral, Red affected by effector.
Along surface (as the tutorial shows for the "scales").


Here are my nodes and blendfile:



PS:
I made that one blendfile, but I took the next blendfile from here:


https://drive.google.com/file/d/0ByYo18t3qZRLajNDejF6eFVnYmM/view

and tried to split and understand what is happening in order to achieve the effect I want.



EDIT because it's not solved yet

Thanks to Omar Ahmad, now I have a clean node way to scale the "pressure arrows" from a empty with a "sphereic falloff" and I mix that idea with a "vertical falloff".

The color works only in "vertical falloff" but the rotation is child of normals... would be to difficult affect the local rotation of the arrows to the same "world side"? I have upper arrows rotating correctly, but below arrows rotating in the opposite direction and middle arrows nothing at all. With the inner faces of a sphere is samething.
To put arrows pointing along the normals of the vertices of a room, you can sample the vertices normals, convert them to Eulers through the Direction To Rotation Node and use that euler along with the vertices locations ro compose a list of matrices representing the transformations of arrows. Then we you can offset those matrices just as you did implementing the variable scale and rotation, and the color can be set as a vertex color just as you did (Making sure Deep Copy is enabled in the instancer node):