Poor Quad to Tri Conversion

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Poor Quad to Tri Conversion

Post by metalliandy »

Hey all,
(After visiting elysiun and posting this, it was suggested that i post it here..so here we are :) )

I have been making some models for a game i am producing and noticed that the Quad to Tri function produces poor results.
By poor i mean that the tris do not seem to follow any particular order.

I decided to run a test.

After creating a cylinder and cutting the centre with the knife tool, then running the conversion, some tris seem not follow the most logical order.
Some go one way and then in the same line of tri's others are flipped.
Does anyone know why this is?

After convertion one would assume that blender would find the most efficient tri layout, but it seems this is not the case.
By more efficient i meant from an engine rendering/GPU point of view...Tristrips are rendered more efficiently in game.
I know that the margin is getting smaller as better GPU's are being released every year, but better is better.

If all GPU's and Engines worked in quads then my job would be allot easier...lol

Of course one could always fix the problem manually but the takes allot of time to do, time which could be spent making more models.
Is there any way to fix this? (apart from working in tris to begin with ;) )

I have attached a gif showing my test, and i hope it explains my rambling more that my power of the English language ever could.

The last part of the image shows in red, the direction that the tri's should follow for the most efficient conversion.


Imagine if the model was a few thousand Tri's and a more complicated mesh, it would take forever to adjust each face to make tristrips.

I would like to see this built in to blender to help game artists as the benefits would reaped quickly.
I know this probably would not effect models built for rendering engines but for games every poly counts, we need our models to be a streamlined as possible, whatever advantage we can get is a help.

How hard would this be implement?

Also it would be nice if when creating cylinders the user could choose whether the tops would be created as tristrips, fans or the default output.
These things all take time to correct when modelling.

Would this be hard to implement to?

Thanks for looking

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Post by joeri »

Hi metalliandy,

In general I think this would be pretty hard to implement. Not in this case maybe, but certainly in most (non-cylindrical) cases.

But I agree that it would be nice if converters start to be more like modelers.
Maybe somebody can pick this up as a SoC project.
The beautyfill was created out of this frustration, me and Ton came up with the idea that all areas of all polygons should be about the same. We would need a discription like that for this for programmers to be able to implement it. Something like all verteces should have as less edges connected as possible, or so.

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Joined: Tue Apr 24, 2007 12:35 pm

Post by metalliandy »

Thanks for the reply!

Maybe a description like all faces should lean the same way in the current ring/loop but opposite to the ring/loop above and below?

one can always live in hope!

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