Hi…
I’m trying to make a terrain with two blended textures, now my idea is to make two rendering passes, the first with per example stone texture, and de second with another texture (grass), and I want that the RGB values of the second pass be added to the RGB values of the first pass depending on a factor (F)
For the second pass, set the fragment color to (1.0, 1.0, 1.0, 0.2). Make sure GL_MODULATE texture mode is being used. Set the source blend factor to GL_SRC_ALPHA and the destination blend factor to GL_ONE_MINUS_SRC_ALPHA.
I’d surely think the G400 supports alpha blending, but it appears not to in this instance. You might want to double check that to see if it does. Or try to run the app using a different video card like a TNT or GeForce and see if the problem exists on them. That’ll narrow it down to either a hardware (or hardware driver) issue or a bug in the app.
I’ve since checked the G400 specs and they do claim to support all OpenGL blend modes.
So I’d now think it is either a bug in the OpenGL ICD, or a bug in the app. You certain you have the latest driver and ICD for the card? If so, then it is surely a bug in the app, somewhere.
[This message has been edited by DFrey (edited 10-18-2000).]
What is your glTexEnv settings? make sure you use something like GL_MODULATE on the second pass. If not, the alpha may be taken from the texture instead of the glColor value, and if your texture doesnt contain alpha information, I believe it will default to 1.0