VP2 MRenderItem assign unique color per point

[Ryan Nolan]

Hey everyone,

I'm currently using the OpenMayaRender.MPxSubSceneOverride to visualize some custom data in the viewport.

In the simplest terms what I'm looking for is to create a point cloud, with each point having a unique color. Kind of like rgbPP on particles.

What I want to do is create 1 MRenderItem, fill the vertex buffer with all my point positions. And then via one of the ShaderManger stock shaders assign some unique colors to each of the points.

I thought the "k3dCPVFatPointShader" would be the answer to my issue but it doesn't seem to work. The color of all my points stay the stock color of blue.

I feel like what I'm attempting to do is really simple, I'm just missing something. Anyone ever have any luck assigning colors to points that exist within the same render item? Is it possible using the stock shaders?

Here's what I have at the moment:

vboPosDesc = OpenMayaRender.MVertexBufferDescriptor("", OpenMayaRender.MGeometry.kPosition, OpenMayaRender.MGeometry.kFloat, 3)
vboColorDesc = OpenMayaRender.MVertexBufferDescriptor("color", OpenMayaRender.MGeometry.kColor, OpenMayaRender.MGeometry.kFloat, 3)

def createPointCloud(self, container):
    shader = self.shaderMgr.getStockShader(OpenMayaRender.MShaderManager.k3dCPVFatPointShader)  

    positions = VBO_Pos.acquire(numPoints, True)
    colors = VBO_Color.acquire(numPoints, True)
   
    numPoints = 1000
           
    VBO_Pos = OpenMayaRender.MVertexBuffer(vboPosDesc)
    VBO_Color = OpenMayaRender.MVertexBuffer(vboColorDesc)
   
    floatinc = sizeof(c_float)
   
    pid = 0
    for x in xrange(numPoints):
        c_float.from_address(positions + (pid) * floatinc).value   = random.uniform(-500, 500)
        c_float.from_address(positions + (pid+1) * floatinc).value = 0.0
        c_float.from_address(positions + (pid+2) * floatinc).value = random.uniform(-500, 500)
       
        c_float.from_address(colors + (pid) * floatinc).value   = random.uniform(0,1)
        c_float.from_address(colors + (pid+1) * floatinc).value = random.uniform(0,1)
        c_float.from_address(colors + (pid+2) * floatinc).value = random.uniform(0,1)
       
        pid+=3
       
    VBO_Pos.commit(positions)
    VBO_Color.commit(colors)
   
    item = OpenMayaRender.MRenderItem.create("pointCloud", OpenMayaRender.MRenderItem.DecorationItem, OpenMayaRender.MGeometry.kPoints)
    item.setShader(shader)
    container.add(item)

    buffers = OpenMayaRender.MVertexBufferArray()
    buffers.append(VBO_Color, "color")
    buffers.append(VBO_Pos, "positions")

    self.setGeometryForRenderItem(item, buffers, None, None)
   
    self.shaderMgr.releaseShader(shader)
   
    return item

P.S. I have successfully gotten what I want by creating a renderItem containing 1 point, instancing that point to all the positions I want, then overriding the "solidColor" attribute on the shader via the "setExtraInstanceData" method. But that seems to run about 4-5 times slower than having all the points within the same RenderItem

Thanks a lot in advance for any help on this :)

Cheers,

-Ryan