I''ve been experimenting with 3d painting recently, as I plan to make an open source 3d painter. But have come into trouble with an approach I''m using. I was generating an image where each pixel has a unique color. Then drawing the mesh using this unique image as the texture. The idea was to then glReadPixels and find the color where the mouse is, then search for this color on the unique texture. This way finding the uv coordinates for where the mouse was clicked( the place on the texture the user plans to paint). However it turns out that the color returned is not quite what it should be. I have disabled GL_BLEND, GL_DITHER, GL_FOG, GL_LIGHTING, so that they may not make the color of my choosing different. To stop interpolation of the texture I have used: glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST) glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST) I have set glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL) None of this seems to work, so I fear the worst. Can someone please help me in this, with suggestions on how to fix this problem or to suggest another method?