Is it possible, to draw a quad (consisting of (forExample) 9 vertices), in ONE triangle strip ? The quad: 0 1 2 3 4 5 6 7 8 If I could do that, it would give my app a hardcore-speedUp. I''ve wasted thousands of pencils and sheets of paper to solve this prob, but I failed....... My best approach was this one: 0, 3, 1, 4, 2, 5, 8, 4, 7, 3, 6 But it''s buggy... ( Because of 2, 5, 8 ) :-((( Do you have an better idea ?

Sorry if I''m not being too helpful here, but why does the quad need 9 vertices? If it''s really a quad you only need the 4 corners. Vertices 1,3,5 and 8 must be in line with the edges of the quad and 4 isn''t needed either. In that case you could do it in a triangle strip.

With "quad" I mean that it has a square shape. And mkaltner said, I need it for a landscape (You''re smart ;-)).
But as some of you said, I can''t use a fan, because the real size is 33x33 vertices (This here is just a simplyfied example).

My biggest problem is that I need 32 calls to glDrawElements(), to draw my quad. If I could draw all triangles with ONE call, the frame rate would be twice as high !!!
(I tried that, but I don''t know how to bring the vertices in a proper order)

Could anyone tell me what other possibilities I have to draw such a quad ? Perhaps I could tell glDrawElements() to draw it as triangles (not as a strip). How would my vertex-array have to look like then ?

thx, VanKurt

One quick note... while your use of "quad" in the sense of a 4-sided figure is valid, the term "quad" in a computer graphics context usually means two triangles stuck together. Minor point, but as mentioned, it helps to avoid confusion.

What you are looking to do can be done with the help of degenerate triangles. A degenerate triangle is one with no area; it can be created by duplicating a vertex index. Most 3d hardware can recognize these and either efficiently drop them or render them (which, since they are degenerate, does not affect output).

So, one way to tristrip your square mesh would be:

0 3 1 4 2 5 5 8 7 4 3 6

or even

0 3 1 4 2 5 5 3 3 6 4 7 5 8

Don''t immediately throw out the last because it''s longer... (nor immediately accept it because I told you not to throw it out). There are many factors involved in getting full performance. Vertex cache is one, and potentially neither of the above are the best way to do it (for longer strips, that is). Some platforms, also, could do this without degen tris (PS2, for example) by using draw kick bits... not that the PS2 can''t handle a degen, but it may be better to do it other ways and save a little DMA.

Anyway, try the degens and see if it works for you. Then figure out your hardware to get the best efficiency.


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