I have a problem which is driving me crazy. Enironment: IPHONE, OpenGL ES 1.1 Basically I have a simple GL_COMBINE for vertex color and texture color. glColor4f(0.1f, 0.1f, 0.1f, 0); glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE); glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_ADD); glTexEnvi(GL_TEXTURE_ENV, GL_SRC0_RGB, GL_PRIMARY_COLOR); glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR); glTexEnvi(GL_TEXTURE_ENV, GL_SRC1_RGB, GL_TEXTURE); glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR); glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_ADD); glTexEnvi(GL_TEXTURE_ENV, GL_SRC0_ALPHA, GL_PRIMARY_COLOR); glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_SRC_ALPHA); glTexEnvi(GL_TEXTURE_ENV, GL_SRC1_ALPHA, GL_TEXTURE); glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_ALPHA, GL_SRC_ALPHA); It should simply do VertexColorRGBA + TextureRGBA. With Alpha everything works fine, but if as soon as I change R,G,B in the glColor4f call, the final alpha is also modified. Does anyone have a hint for this unexpected behavior? Thanks in advance! Ivica