im trying to draw a glowing texture and after reading this post: Opengl ES 1.x glowing effect in iOS. I have used this glBlendEquationOES(GL_MAX_EXT) command which makes the effect i wanted but the problem is it makes everything else corrupted. i wonder how can i disable glBlendEquationOES(GL_MAX_EXT) after i use it? or return it to default mode? Thanks! Guy.
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You can `glDisable(GL_BLEND)` it. I think it defaults to `GL_FUNC_ADD`; didn't find this info anywhere, though. – Stefan Hanke Apr 13 '12 at 11:41
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You disable blending by... disabling blending. You enabled blending by calling glEnable(GL_BLEND). So turning it off means calling glDisable(GL_BLEND).
The blend equation/funcs can remain as you want. You don't have to set them to default or to any particular value. Disabling blending means that their values are irrelevant.
Nicol Bolas
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I forgot to mention that im using cocos2d engine and by calling glDisable(GL_BLEND) it messed up the drawing made by cocos2d, stuff like CCSPrite and CCParticles, i used stefan solution and found that GL_FUNC_ADD_OES value is the "default" value for glBlendEquationOES. thank you all for the help, i have only basic opengl knowledge :) – steve88 Apr 14 '12 at 09:17
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Have you tried saving and restoring the graphics state?
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSaveGState(context);
// graphics state corrupting code ...
CGContextRestoreGState(context);
bshirley
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