OpenGL ES Textures with alpha layer not working with Colorpointers

Question

Hey,
I'm trying to get a texture - that's loaded from a .png file - to fade out gradually. I can load it using the Apple's "Texture2d" class and present it with its own transparency. The problem is when I try to combine that transparency with a color pointer. I'll try to give an example code...
const GLubyte squareColors[] = {
128, 128, 128, 128,
128, 128, 128, 128,
0, 0, 0, 0,
0, 0,0, 0,
glColorPointer(4, GLUNSIGNEDBYTE, 0, squareColors);
glEnableClientState(GLCOLORARRAY);
glEnable(GLTEXTURE2D);
glEnableClientState(GLTEXTURE_COORDARRAY);
glEnableClientState(GLVERTEXARRAY);
glTexEnvi(GLTEXTUREENV, GLTEXTURE_ENVMODE, GL_REPLACE);
glEnable(GL_BLEND);
glBlendFunc(GLSRCALPHA, GLONE_MINUS_SRCALPHA);
for (Sprite *element in dynamicBodies) {
glLoadIdentity();
[element renderSprite];
Now, if the original .png happens to be completely opaque, it gets darker and transparent because it gets multi-sampled with the color matrix. But if it has any see-through parts in itself, it does not get affected by the the color.
I'm sure it has to be possible to change the alpha percentage of an alpha layered texture, but I can't seem to find another way.
Does anyone happen to know why this does not work, or how it could be accomplished some other way? I would be highly appreciative.

Answer 1

You set your texture environment mode to GL_REPLACE. The implementation of this feature is to replace the primary color (set via ColorPointer or Color3f) with the sampled texture value, so your color will have no effect.
Replace the texture env mode with GL_MODULATE, which will multiply the Texture Unit Input Color (==PrimaryColor for Texture Unit 1) with the sampled texture value.