when using multitexturing with 2 textures, is it possible to change the transparency of the second (overlayed) texture dynamically? i’d like to have an image texture to a wall with a second texture on it that fades in and out all the time. also, can the modulation color of the second texture be dynamically altered?
You can use ARB_texture_env_combine. First texture unit should use the replace function, and the second texture unit should use the interpolate function to interpolate the result from the first unit and the texture on the second unit, using, for example, the primary color as interpolation factor.