polys vs vertices

I think this has been asked before but I can't find it. I know it takes engine time to draw polygons but does the vertex count decrease FPS as well?

well, the vertex count is related to the poly count.
if your model has alot of polys, it will have a lot of vertices.
a single polygon has at least 3 vertices.

so u dont have to think about the vertex count. just count the polys.

i hope this helps you out.... im not sure if understood your question right.
english is not my mother tounge.

cheers

sinnlos

Vertices are more important to the frame rate than polygons are. From a test I did a while ago, a model with 30,351 vertices and 60,000 faces took half the time to render than did a model with 60,000 vertices and 30,000 faces. Always merge your vertices and use as few as possible. If it means having polygons intersecting, then do it if it doesn't pose any problems.

thanks uli.

i think thats not because of the high vertex count itself, but bacause of the fact, that a model with a lot more vertices than faces also has a very dirty mesh and so it takes more time to render ans slows down the engine.

It all depends on the time the graphics pipeline needs to draw a polygon. If you have a plain color most of the work is done by the vertex shader (included gouraud shading). If you use a texture high poly/low vertices models are rendered slower (depends on how the uv map is used). If you use a pixel shader it's even slower (like per pixel normalmapping).

vertices have to be 3d-transformed, transformed for animation,... so of course vertex count matters.

i think with triangles it's more the amount of overdraw they cause (how many pixels have to be drawn) than the number of them.

the number of triangles and vertices most of the time is quite related anyway though.

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the number of triangles and vertices most of the time is quite related anyway though.

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I agree with this. Normally, there are twice as many triangles as vertices, always true in a closed mesh.

With just 100 vertices, you can theoretically have up to 9604 triangles. I may have stated that, with the maximum of 65,535 vertices that it was some extremely high number - I used the wrong formula. It's not pow(2, vertices-2), but rather pow(vertices-2, 2). With the maximum, you can have, theoretically, 4,294,574,089 triangles.