how to draw a geometry with higher teseellation

the geometry with higher tessellation looks more reasonable in some effects,but how to draw it?

Originally posted by pango:
the geometry with higher tessellation looks more reasonable in some effects,but how to draw it?

how to render more polygons ? just throw more polygons at your gpu !!!
but seriously: i think you are lookng for tesselation and subdivision algorithms. just google for: “subdivision surfaces”, “bezier”,“bezier patches” or “polygon tesselation”.

another thing is that chip vendors are providing specific technology/extensions for such kind of polygon tesselation. i don’t know what nVidia did exactly, but ATI has their TRUFORM technology, which does the polygon tesselation assuming the polygon vertex normals and gives a subdivision of a particular polygon and represents a convex shape of it in a set of a smaller triangles, giving a smoother looking surface as a result. Minus of this one is that it is done in software(driver) , but i believe it is optimized in any way so that it can work better than any algorithm you will use Here you can find some info on TRUFORM technology and PN Triangles extension for it(ATI_pn_triangles):

“ATI’s TRUFORM™ implementation occurs completely in silicon.”

says so in the doc.

oops, sorry – this what i’ve read that confused me a bit about it, heh:

Some games may actually allow TRUFORM™ to be rendered in a “software” mode on hardware which does not directly support TRUFORM™. While this will add visual appeal, it requires more of the system CPU cycles. This can significantly reduce a game’s frame rate.


With a product that supports TRUFORM™ in hardware, such as the RADEON 8500, the graphics rendering occurs within the Graphics Processing Unit (GPU). The games visual appearance is greatly improved, while having a minimal affect on frame rates.

sorry for a confusion!

ATI’s marketing material is a bit misleading. There are exactly two graphics cards known to man that implement n-patch tesselation (aka TruForm) in hardware:
Radeon 8500 (/LE)
Radeon 9100

Everything else is software preprocessing. And slow.