   [SlimDX] Specifying alpha for simple vertex buffer primitives
  I have a vertex buffer which specifies a simple unit-square quad mesh. The vertex buffer consists purely of positions. What I want to do is draw the quad with various [colours and] alpha values. That means I can't specify the colour as part of the vertex buffer format.How can I specify what colour (including alpha) to draw the quad? I got this working before with a textured quad, but this simpler scenario seems to be giving me more problems! :)   
Quote:What I want to do is draw the quad with various [colours and] alpha values. That means I can't specify the colour as part of the vertex buffer format.Actually, it means you must specify color as part of the vertex format used by the buffer (or by assigning the FVF or vertex declaration appropriately).The only other option is to set up a shader with a parameter for color (including alpha) set that parameter before you draw each quad, and render using them (and that's only if you want each quad to be one complete color).   ;  So I can't, for example, define a unit quad (1x1 units) which is opaque white by default, and alter the render state to change the colour it is actually rendered with? I achieved an effect very similar with a textured unit quad (allowing the colour, including alpha, to be changed on the fly) with the following adjustments to the device:device.SetTextureStageState(0, TextureStage.AlphaOperation, TextureOperation.Modulate);device.SetTextureStageState(0, TextureStage.AlphaArg1, TextureArgument.Texture);device.SetTextureStageState(0, TextureStage.AlphaArg2, TextureArgument.TFactor);device.SetRenderState(RenderState.TextureFactor, colour);Where 'colour' could be altered accordingly. Of course, this seems to be very texture-centric, but you're saying there isn't a similar method for doing what I want to achieve with a non-textured quad? :(   ;  You might be able to do it by screwing around with materials and other fixed-function weirdness -- at the very least you could replicate what worked with a texture and use a blank white texture instead -- but I don't know much about the fixed function aspects of the API offhand, since they are dead technology.   ;  Indeed. I've love to move on to the newer Direct3D stuff - shaders, the programmable pipeline, but unfortunately I'm having to code for extreme compatibility at the moment.Hopefully someone else can help me? I've had a go at materials, etc, but with no luck so far.   