   Drawing the alpha channel from a texture?
  Hi guys!I have a floating point GL_RGBA texture, and I want to draw the alpha channel from it, but how can I do that (of course without using shaders, with that, it would be simple)? I have tried to use pixelstore functions but no success this far.Any ideas?regards, Pal.   
  Short answer: use a shaderOf course, you could always load the RGBA image as AAA by modifying your image-loading routine . . .   ;  Short answer, I don't want to, but if it's the only solution... (and yes I'm loading the image as an AAA rgb texture)   ;  I think what Geometrian was saying is that when you load the texture, you can modify the array you pass to OpenGL such that the R, G and B channels all have the same value of the A you're loading. Then just tell OpenGL it's an RGB texture.   ;Quote:Original post by sirpaleeShort answer, I don't want to, but if it's the only solution... (and yes I'm loading the image as an AAA rgb texture)If you are changing filling the rgb part with A then I fail to see what the problem is.   ;  Curious. Almost pathetic.Check if GL_SUN_slice_accum is available, then use this before rendering:glAccum(0x85CC, 1);after:glAccum(0x85CC, 0);;Quote:Original post by AngeliqueCurious. Almost pathetic.Check if GL_SUN_slice_accum is available, then use this before rendering:glAccum(0x85CC, 1);after:glAccum(0x85CC, 0);Thx, I'll try it out.   ;Using glTexEnv, set up the fragment colour to be texture_alpha * constant colour. You set the constant colour to be white. Set the fragment alpha to be a constant 1. Do the texturing. Bingo, one visible alpha channel.