I posted this question in the advanced forum, but no body seems to answer!!!???
I’m a bit confused about how OpenGL performs clipping on primitives. Does it clip at rasterization time (clips per-fragment against the viewport) or does it use clip planes and do vertex inside/outside plane test?
If 3D clipping (the later approach) is used, there will be a problem. when passing a primitive, say a triangle strip, and it’s partially clipped, a new vertices will be added. How does OpenGL take care of this?
Thanks.
This is two things: A crosspost, and a RTFM post (hint: read the API specification).
[This message has been edited by Bob (edited 03-20-2002).]
Its not strictly a cross post. If WM’s being truthful he tried somewhere else and when they did not answer he tried here. That’s the correct thing to do, only WM did it the wrong way round. Usually you post to the beginners forum first, and if they can’t answer then you post to the advanced forum.
Based on what I see happening in the advanced forum it may be that the question was ignored because it was a beginner’s question. Either that or WM did not wait long enough for an answer.
[This message has been edited by Furrage (edited 03-20-2002).]
Clipping is done on primitives before rasterization.
BTW, I didn’t know the answer to this question before now and it took me less than 30 seconds to find the answer: grab the book -> look up “clipping” in the index -> go to page 12 -> read. I suppose that is why you were ignored in the advanced forum, but RTFM certainly has a much lower threshold in the beginner forum.