draders's picture

VBOs with colours


I am using vertex buffer objects based on the code found at http://www.opentk.com/node/425 and have it all working well except it renders fully opaque despite the colours having a non opaque alpha channel.

Here is the rendering portion of the code:

    // Colours
    if (vbo.ColourId != 0) {                    
        GL.BindBuffer(BufferTarget.ArrayBuffer, vbo.ColourId);
        GL.ColorPointer(4, ColorPointerType.UnsignedByte, sizeof(int), IntPtr.Zero);                    
    // Vertices
    GL.BindBuffer(BufferTarget.ArrayBuffer, vbo.VertexId);
    GL.VertexPointer(3, VertexPointerType.Float, Vector3.SizeInBytes, IntPtr.Zero);            
    GL.BindBuffer(BufferTarget.ElementArrayBuffer, vbo.ElementId);            
    GL.DrawElements(BeginMode.Triangles, vbo.ElementCount, DrawElementsType.UnsignedInt, IntPtr.Zero);

Is there some cap/mode I need to enable in order for this to work?



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the Fiddler's picture

Yes, you need to set a blend mode and enable blending. Check out the blending documentation.