GL_NV_texture_env_combine4 or Register combiners
For some vague reason I need to soften textures averaging nearby pixels, What I am trying to do is Draw a single Quad with the same texture bound to both the units with a small jitter in the texture coordinates. I do this multiple times to get an averaged pixel.
My math for the averaging at the pixel level is as follows
pixel = Texture0*Weight0+Texture1*Weight1
I can supply these Weight0 as Primary color of the fragment and Weight1 as a constant if I am going to use GL_NV_texture_env_combine4 or send it as the secondary color If I decide to use the Register combiners. My question here is, which technique would be faster, using the env combiners or the Register combiners. I can do this with just the first stage of the register combiner.
Could anybody let me know which one would yield faster results, or the penalty for using register combiners for this?
And does env_combine4 setup register combiners to do its job or does it use some other technique?