FAQ/Clipping, Culling, and Visibility Testing

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Revision as of 18:31, 7 February 2015 by Alfonse (talk | contribs) (Alfonse moved page Clipping, Culling, and Visibility Testing to FAQ/Clipping, Culling, and Visibility Testing without leaving a redirect: This is a FAQ page, so it should be under the FAQ/ subheading. Nothing links to it or its redirect, so it'...)
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Clipping
How do I tell if a vertex has been clipped or not?
When an OpenGL primitive moves placing one vertex outside the window, suddenly the color or texture mapping is incorrect. What's going on?
I know my geometry is inside the view volume. How can I turn off OpenGL's view-volume clipping to maximize performance?
When I move the viewpoint close to an object, it starts to disappear. How can I disable OpenGL's zNear clipping plane?
Occlusion Query
How do I perform occlusion or visibility testing?
FAQ/Stencil Mask
How do I render to a nonrectangular viewport?
Raster Position And Clipping
How do I draw glBitmap() or glDrawPixels() primitives that have an initial glRasterPos() outside the window's left or bottom edge?
Scissor Test And Framebuffer Clearing
Why doesn't glClear() work for areas outside the scissor rectangle?
Culling
How does face culling work? Why doesn't it use the surface normal?