Subject:
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Re: LDForge - dev. plans
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Newsgroups:
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lugnet.cad.dev
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Date:
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Thu, 1 Apr 2010 09:28:15 GMT
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Viewed:
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30511 times
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In lugnet.cad.dev, Travis Cobbs wrote:
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In lugnet.cad, Santeri Piippo wrote:
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In lugnet.cad, Travis Cobbs wrote:
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The only polygons that LDView sorts are transparent ones. Everything else
is handled by the OpenGL depth buffer (glEnable(GL_DEPTH_TEST), followed
by glDepthFunc(GL_LEQUAL)). Transparent polygons need to be sorted before
being drawn, and LDView does what you describe above for those. (There’s
more to it than that for transparent polygons; sorting is just one step.)
Sorting by the distance to the centroid is only an approximation, but it’s
good enough to look pretty good for transparent polygons. It’s not good
enough to be used as the primary means of hiding geometry that’s farther
away from the viewer.
--Travis
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I see.. but problem is that if I use glEnable(GL_DEPTH_TEST) then my
polygons won’t render at all. Tutorials related to OpenGL explicitly told
not to use GL_DEPTH_TEST because of this.. how did you avoid it?
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In order for GL_DEPTH_TEST to work, you have to clear the depth buffer at
the same time you clear the rest of the screen:
glClearDepth(1.0);
glClearColor(0.0, 0.0, 0.0, 0.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
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(Note: the glClearDepth() and glClearColor() calls above aren’t really
necessary, since they pass the OpenGL default values, but just in case you
used some other value, the above is what you want for glClearDepth().)
--Travis
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Ah, thank you Travis! I got depth buffering working now. :)
No more problems with polygon sorting..
-Santeri
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Message is in Reply To:
 | | Re: LDForge - dev. plans and call for help
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| (...) In order for GL_DEPTH_TEST to work, you have to clear the depth buffer at the same time you clear the rest of the screen: glClearDepth(1.0); glClearColor(0.0, 0.0, 0.0, 0.0); glClear(GLCOLORBUFFERBIT GLDEPTHBUFFERBIT); (Note: the (...) (15 years ago, 31-Mar-10, to lugnet.cad.dev, FTX)
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