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transparency question

Started by whitedragon101 Sep 18, 2006 at 9:42 AM 2 replies 400+ views

Original Post

Sep 18, 2006 at 9:42 AM

I have tried a couple of blending tutorials for making 3D objects transparent. The main problem is when I try it with a large number of cubes in line (mostly red in colour) the colour becomes white. Is there any way around this?

Silverclaw

Sep 18, 2006 at 9:45 AM

Experiment with different blending equations (glBlendFunc). You problably have a adding equation "GL_ADD" or something like that. Try other equations to achieve better results. Also, consult the Red Book for available constants.

whitedragon101

Author

whitedragon101

Sep 18, 2006 at 9:48 AM

My current equation is:

glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

which works for a small amount of objects, but once I start to rack up the number of cubes the cumulative colour becomes white.

Silverclaw

Sep 18, 2006 at 10:05 AM

Replace GL_ONE_MINUS_SRC_ALPHA with

GL_ZERO; GL_ONE; GL_SRC_COLOR; GL_ONE_MINUS_SRC_COLOR; GL_SRC_ALPHA; GL_ONE_MINUS_SRC_ALPHA; GL_DST_ALPHA; GL_ONE_MINUS_DST_ALPHA

Now try with these different constants and see what results come out. Again check the redbook on Blending or the OpenGL programming guide.

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