I have a problem with drawing one big polygon. It is supposed to be some sort of surface. But anyway, it is huge (far clipping plane approx. 500, polygon is 2 000 x 2 000).
It is multitextured with two textures.
When it intersects only the left, top, right and bottom cipping plane, everything is OK. But when it intersects the far clipping plane, it seems like OpenGL switches to SW rendering. Performance slightly goes down, but the rendered results are terrible, it looks like without using bilinear filtering.
Forgot to add: the texture on unit 0 is tiled about 500x500 times. If I lower it to only 5x5 the visual problems are (at least seem to) be solved, but the performance is still low (screen without this big polygon 80fps, with polygon 40fps)
Why not break the polygon into smaller polygons. Break your 4 sided polygon into 2 triangles and then take the centroid and create 3 new triangles. Repeat the process until the size is good enough.
This will also produce shining spots from light sources at the centroid.
I had something like this happen to me, reduce your far clipping plane… say you have 1.0 to 1000.0, reduce it to 1.0 to 100.0 if you can that is… worked for me