Tri-strips

[dwalden74]

I love tri-strips...especially grilled ones... mmmmmmm....

[alexx]

what the heck is a tri-strip??

[dwalden74]

what the heck is a tri-strip??

You mean you don´t know?!? :shame: (gulp)... how embarassing...

[alexx]

never heard before

[mhovland]

The problem with implimenting tri-strips in Maya is that the implimentation you get may not be using the same algorithm to generate the strips, as the one in your engine.

This is something that would be best done by a programmer internal to each individual project, who is familiar with the algoritm used by the engine.

For those who don't know what tri-strips are.....

It is a method of storing geometry that reduces file sizes as well as improves draw speed in game engines.

If you look at the attached image, to define the first poly (verts 1,2,3) you need 9 floats to represent where the verticies are in 3d space (verts 1(x,y,z), 2(x,y,z), 3(x,y,z)).

To define the second poly (verts 2,3,4), you need 3 floats (vert 4(x,y,z)) the other two verts that make up that poly are already stored.

The down side to this is that there are a number of things that will break a strip, including seperate textures on adjacent polys, seperate vertex colors (hard edges), and if the internal edges are not all going in the same direction. If the strip is broken, you could get degenerate polys (invisible polygons that the exporter will build inbetween two adjacent polys that otherwise would form a valid strip).

I have found that it is a give and take, to determine if tri-stripping will be beneficial on an object by object basis.

[mhovland]

Ooops.

[magilla]

thanks for that great explanation mhovland...

i know our engine triangulates differently to Maya so I guess that would be a factor to incorporate into the script/shader. But all of the things you mention are independant of the export/game engine.

UV's are constant - as are hard edges etc and we mostly do manual triangulation - so even that is predetermined in Maya.

Even if it's not 100% accurate I'm sure it would be possible to vaguely predict how efficient the tri-strips are using some type of shader in Maya.

--magilla

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