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X Abstract X

GLSL Textures and Alpha Blending

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EDIT: I fixed this. I was using SDL_DisplayFormat() to convert some surfaces before creating textures and apparently it messes up their alpha value or something. Fixed by using SDL_DisplayFormatAlpha() or SDL_CreateRGBSurface().


Yesterday I made a post about having some alpha blending issues and I think I might have found the problem to be in my GLSL fragment shader. My problem was, when I used glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA) all of my geometry would disappear. None of the other blending functions seemed to work properly either.

My Fragment Shader

#version 130

uniform sampler2D colorMap;


in vec4 frag_texCoord;
in vec4 frag_color;


out vec4 out_color;


void main() {
vec4 texel = texture2D(colorMap, frag_texCoord.st);
out_color = vec4(texel.rgb * frag_color.rgb, frag_color.a);
//out_color = frag_color * texel;
}




So, the line I commented out above was what I had before, when I had problems with alpha blending. Was my shader wrong before, or is it wrong now? Can someone explain this to me, doesn't the texel have an alpha component?

[Edited by - X Abstract X on July 19, 2010 9:17:41 AM]

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