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Vertex Arrays ?, are they any good ??

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Hi, I''ve been taking a look at Vertex Arrays for the first time. Although I can see that using them can give greater speed inceases and keeps your code cleaner, there are a few points that I dont understand.. can anyone please help me out ? 1. If you want to use different textures on different parts of your mesh you''d have to define separate arrays ? (As there''s no array for specifying what texturemap it should read from) 2. Also texturing.. If for example, I defined a cube using vertex arrays with texture coordinates, you would need 24 separate vertexes (4 per side) so that you can setup the texture coordinates correctly and have the texture reading correctly on all sides. 3. Without using the LOCKING commands, is there much improvement using the arrays over a bog standard structure array ?. Thanks !.

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1) No, you''d have to use many glDrawElements calls; but the vertices (and indices) can be in the same array.

2) That''s true, but it''s still better than the 36 glVertex3f calls you''d need with glBegin/glEnd.

3) If by "locking" you are refering to the compiled vertex array extension, then you''d see an improvement for non-T&L video cards ( it works pretty well on the TNT for example ). If you are refering to D3D''s lock/unlock commands, there is no equivalent in OpenGL. Generally, you shouldn''t expect a big speed increase when going from glBegin/glEnd to vertex arrays, unless you become CPU limited ( ie. drawing frames with 100 of 1000''s of triangles ! ).


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