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Index › Programming Questions & Help › OpenGL and 3D Libraries › problems with blending
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problems with blending (Read 683 times)
yoshi95
problems with blending
Mar 6th, 2008, 11:09pm  
i m modifying the spacejunk example code.

what i have done is instead of drawing a box, i draw a rectangle in space and bind a png texture to it. the png file is the outline of a bird on transparent background.

heres a pic (http://www.freewebs.com/yoshi95/blend.jpg)

i circle the problem spots in red.

some spots are transparent, meaning the stuff behind it shows through, and some spots are completely opague.

any idea y this is happening? do i need to tweak the blend mode using glTexEnvi?

thanks in advance
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JohnG
Re: problems with blending
Reply #1 - Mar 7th, 2008, 12:39am  
I think this is due to depth sorting. You need to draw the things further away before the closer things for them to show through properly.

I think there's a hint(DEPTH_SORT); or similar to get processing to attempt to do this for you automatically.
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Cycleswithin
Re: problems with blending
Reply #2 - Mar 17th, 2008, 12:26pm  
Do you know about this...?

http://www.flight404.com/blog/?p=71

There is a bit that fixes overlap issues.

Sorry if this isn't relevant - i'm a newbie to openGL!
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fry
Re: problems with blending
Reply #3 - Mar 17th, 2008, 8:38pm  
yoshi95 wrote on Mar 6th, 2008, 11:09pm:
some spots are transparent, meaning the stuff behind it shows through, and some spots are completely opague.

see the (~7th) item under "common problems" on the troubleshooting page.
http://processing.org/reference/troubleshooting/index.html#opengl
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