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2D Texture Alpha Transparency

Started by Erondial Mar 25, 2006 at 6:17 PM 1 replies 800+ views

Original Post

Mar 25, 2006 at 6:17 PM

I'm sorry for dumping threads and problems on you guys, but I just don't know where to go from where I am... I've loaded my png into an unsigned character buffer, loaded that as a texture, clamped it to a quad, and everything's peachy, except that the area that's transparent, isn't. I've enabled bledning with glEnable(GL_BLENDING);, I've set the blending function with glBlendFunc(GL_SRC_ALPHA,GL_ONE);, and set the colour as such: glColor4f(1.0f,1.0f,1.0f,1.0f);... I loaded the texture with glTexImage2D(GL_TEXTURE_2D, 0, 4, structure->w, structure->h, 0, GL_RGBA, GL_UNSIGNED_BYTE, structure->data);, so yes, it DOES have an alpha channel... I just don't know what to do? Why isn't it working?

Sumo

Mar 25, 2006 at 11:03 PM

You may have loaded the texture with an alpha channel but is the alpha channel actually encoded in the png? Also, I tend to use glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA). You then keep depth testing on and draw things from back of the scene to front.

Erondial

Mar 25, 2006 at 11:10 PM

... I brought it down from 65x65 to 64x64 in paint... and paint doesn't support alpha channels. Argh. Okay. Thanks :)

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