OpenGL Specification 4.0 and 4.1 error

david_f_knight · December 8, 2010, 1:22pm

A thread in the Advanced OpenGL forum discusses an error in the OpenGL 4.0 and 4.1 specification:
http://www.opengl.org/discussion_boards/ubbthreads.php?ubb=showflat&Number=287368

Further discussion of this issue belongs here in this forum.

To summarize:

dave_xyzw:

I am a bit confused about tessellation levels as described in the OpenGL specification, as well as their implementation. I’m hoping that someone here can help.

First, Figure 2.7 in the 4.1 core specification seems to indicate that Outer Level 0 (OL0) determines the number of isolines, each of which has a constant value for v. The number of subdivisions along a particular isoline then is determined by Outer Level 1 (OL1). However, near the bottom of page 120, it says, “each strip has a constant v coordinate…the number of segments in each strip is derived from the first outer tessellation level.”

The latter statement doesn’t seem to jive with the Figure. Am I interpreting this correctly?

In addition, when testing this out on a ATI 5670, Outer Level 0 seems to be the one that determines the number of segments in a given isoline. Therefore, it seems to follow the latter interpretation.

system · October 19, 2021, 7:24pm

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