Polygon counts VS Frame rates

[Al Gay]

I recently made a wheel in GMax, I used 24 sides and 1 increment high. The poly count on this was of course 26. I proceeded to remove the "side lines" until there were only two left, one on either side of the wheel. I now had only four polygons. I left the vertices's in place and it retained it's shape of a wheel with only the four polygons, I textured it and it gave me a real nice circle with no corners showing. I did try removing all of the side lines except one, leaving only three polygons, but I seemed to lose the shape of the object.

My question is: After removing 20 polygons but leaving the vertices's in place, will this have an affirmative effect on frame rates? One wheel in a scenery, maybe not, but if this is done every time a circle, cylinder etc was used could it cause better frame rates?

Thanks,

Al Gay
Flight Ontario
www.flightontario.com

 

[lmoelleb]

You must count triangles, not polygons, as all 3D models are rendered though lists of triangles.

A polygon with four vertexes will result in two triangles. A polygon with 5 vertexes will give 3 traingles and so on.

So one side of your 24 side wheel will give you 22 triangles (+/- a few to compensate for my brain state after modelling for a whole day).

 

[Al Gay]

Thank you Lars for your reply. I understand the triangle theory. I am still wondering if it is of an advantage to remove lines, there fore reducing the number of polygons, hence less triangles? Or since the vertexes have remained does it still consider the removed lines to still be there?

Al Gay
Flight Ontario

 

[lmoelleb]

Your statement "there fore reducing the number of polygons, hence less triangles" isn't correct - reducing polygons does not necessarely reduce the number of triangles. To do so, the triangles bordering the line being deleted must be on a single plane. They aren't in this case as the wheel is round.

Each of your 24 wheel segments (ignoring the side of the wheel) consist of a square with two triangles. It is mathematically impossible to construct the shape with fewer triangles, no matter what you do. Only thing to do here is to create LoDs with fewer segments.

 

[Al Gay]

Thanks Lars. One could only hope. lol

 

[lmoelleb]

Just to make sure noone digs this out in a few months time and use it against me, I better clarify something:

My statement that the number of triangles can't be reduced when the two triangles bordering the line are not on a single plane is correct, however this should not in any way be ment to imply that the triangle count can be reduced if they are on a single plane.

This is probably a better statement: The triangles count can be reduced if the two triangles bordering the line can themself form a triangle. This should be done manually by welding two of the four vertexes.