"In the beginning the Universe was created. This has made a lot of people very angry and been widely regarded as a bad move."
- Douglas Adams
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Query FailedMo
Friday, January 23, 2009

Drop the m! Keep the underscore! Viva la revolution!
Humus
Friday, January 23, 2009

I used it as an intuitive way to render a circle. Yes, you could drop the center vertex; however, there's no advantage to that. Instead of creating thin triangles towards the center it creates thin triangles across the whole circle and hence performs comparable to strips.
LogicalError
Thursday, January 22, 2009

Why did you make a fan with an extra vertex from the center? wouldn't you be able to make a fan from one of the other vertices (would work with any convex polygon) instead? that would save one vertex and 2 triangles.. would be a more fair comparison i think
Humus
Saturday, January 17, 2009

Rohit Garg,
I don't know what was the exact motivation for removing it in DX10, but it should be noted that fans have very limited utility. Back when people called glVertex3f() and vertex buffers didn't exist and everything was very low-poly anyway I suppose it was nice for some things. Personally the only times I've used it is for things like fullscreen quads, which is equally well done with a triangle strip. I don't think fans are necessarily slower than other primitive types, or if it really takes that much chip area to support, but it just doesn't add any functionality that can't be done with other primitive types. I suppose it also doesn't fit very well with the adjacency stuff for the geometry shader.
Rohit Garg
Saturday, January 17, 2009

Simon,

I meant an object like a cone, for which the natural tesselation seems to be a triangle fan. I wonder why triangle fans have been thrown out in new APIs? Are they inefficient like immediate mode rendering or what?
Seth
Saturday, January 17, 2009

On second thought, they might not be deprecated in OpenGL3. From the specification:

Deprecated: Quadrilateral and polygon primitives - vertex array drawing modes
POLYGON, QUADS, and QUAD_STRIP (section 2.6.1, related descriptions of
rasterization of non-triangle polygons in section 3.6, and all associated state.
Seth
Saturday, January 17, 2009

Rohit Garg,

Triangle fans are already gone in D3D10 and deprecated in OpenGL3. One thing you could do to simulate them, though, is to use an index array to connect the vertices in a similar way.
Simon
Saturday, January 17, 2009

Rohit Garg,

A circle is planar. Do you mean a sphere?
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