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glBlendFunc

Started by F-Kop Jul 4, 2006 at 2:55 PM 2 replies 800+ views

Original Post

Jul 4, 2006 at 2:55 PM

I can't find a place that gives a good explanation of glBlandFunc. What would be the best blend function to use in a 2D game with alpha values of 0 and 255, and nothing in between?

kordova

159

kordova

Jul 4, 2006 at 2:59 PM

I would just use:

glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );

It will do what you want and let you add other values later on.

nullsquared

126

nullsquared

Jul 4, 2006 at 3:07 PM

Quote:
Original post by F-Kop
I can't find a place that gives a good explanation of glBlandFunc. What would be the best blend function to use in a 2D game with alpha values of 0 and 255, and nothing in between?

255 is completely visible and 0 is completely invisible - what's the point of using blending in the first place?

If you're going to use it for a "colorkey" effect then use:

glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

Brother Bob

Mod

218

Brother Bob

Jul 4, 2006 at 3:37 PM

For binary alpha masks you don't use blending, you use the alpha test.

glAlphaFunc(GL_EQUAL, 1);glEnable(GL_ALPHA_TEST);

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