How do I replace a mesh's texture with vertex colours?

Question

I have a textured 3D mesh. I want to deduce a 3D mesh without texture, but with an RGB vector color on each node of this 3D mesh. The colors have to be picked from the initial texture. Is there a way to do this ? My question isn't related to art work. It's related to 3D mesh processing.

Thanks

Answer 1

You can sample the texture in your vertex shader and set the color appropriately. You don't say what system you're using, but for something like an OpenGL vertex shader, it would look something like this (this is a little old school, so it may need updating for modern GL) :

uniform sampler2DRect texture;
varying vec4 color;
void main ()
{
    color  = texture2DRect(texture, gl_MultiTexCoord0.xy);

    vec4    newVertex   = vec4(gl_Vertex.xyz, 1.0);

    gl_Position = gl_ModelViewProjectionMatrix * newVertex;
}

Your fragment shader would then just set the color of the fragment to the interpolated color coming from the vertex shader. Something like this:

varying vec4 color;
void main()
{
    gl_FragColor = color;
}