Im asking this question for a friend of mine. He has an old program thats still using the FFP for rendering in OpenGL. Right now it still all works but there is a new feature hed like to implement. Every vertex has a color value. But its modulated in a different way. In GLSL in the fragment shader it would be like:
gl_FragColor = input_color.rgb * 2 * texture_color;
So essentially a color value of 0x7F7F7F7F would just return the texture color whereas 0xFFFFFFFF would double all channels of the texture.
The color values are bound to a buffer and sent to the FFP using glColorPointer. In DirectX i remember there was some kind of texture sampler state that allowed to specify MODULATE_2X as color operation. Is there something similar in OpenGL?