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223

answers:

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I made a quad with a nice texture on it. The texture has an alpha channel (RGBA). I replaced the quad with the texture (GL_REPLACE), so now I have a billboard with (semi)transparant pixels on it.

So far, no problem.

But now I want to blend the entire billboard, so it's overall opacity changes.

How would I do this?

+1  A: 

GL_MODULATE, instead of GL_REPLACE, after setting the color to solid white, with an appropriate amount of alpha. (glColor(1,1,1,0.5) for instance)

(Should work fine on OpenGL. Seems likely it'll be good on ES, too.)

Jay Kominek
I tried. It doesn't work for some reason? I edited the question with our code.
Kriem
If you just make a texture-less quad which is 1,1,1,0.5 does it appear translucent?
Jay Kominek
Found the error. You're our hero of the day. ;)
Kriem