CODEWITHSUNDEEP
objective-copengl
hockeyman
hockeyman

Reputation: 1183

multiple glBlendFunc for one object

I need to draw textured quad. My texture has some alpha pixels. So I need to do glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

Thats OK. But I need some other blending function on that quad (glBlendFunc(GL_DST_ALPHA, GL_ONE_MINUS_DST_ALPHA);) to achieve textures masking. How can I do it? Because if I set both glBlendFunc, one of them is ignored.

Upvotes: 0

Views: 251

Answers (1)

datenwolf
datenwolf

Reputation: 162297

Blending is a framebuffer operation and can not be set per primitive. If you need to combine several texture layers on a single primitive, do this in a shader and emit a compound color/alpha that interacts in the right way with the choosen blending function. If you need different blending functions, you must do this using separate drawing calls.

Upvotes: 2

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