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Post by pandamontok on Dec 17, 2021 1:25:33 GMT -5
Aren't QUADS the golden rule of a good topology? So why SIMS 4 clothing use TRIS?
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Post by simmerish20 on Dec 17, 2021 3:01:33 GMT -5
If you look at the structure, you can see the quads (rectangles in neat lines, parted into triangles). They're just converted into tris when you put the mesh ingame, or when you export a mesh from the game to Blender. The meshes have good topology, but the "issue" is that the tris are showing. Unfortunately there's not too much to do about that, since exporting from TS4 makes the tris visible.
Here's an example of good flow VS bad flow:
The first example has everything in (roughly) neat lines vertically and horizontally, and you can see the square structure. The second example has everything scrambled, and there's no structure.
Each quad is actually made up from two tris, but when you make meshes with quads this separation is hidden. The game chooses the default setting for which way to split the topology of the tris when you export it to the game, but it's possible to change the direction of the split so it goes the other way. You get the choice of / or \ for quads, and it seems to be a bit randomized. Most of the time it's not important which way it goes, but in some areas where you have tris from the same quad on either side, it can sometimes help to change the direction. If there are more than four vertices on a polygon, you'll get a more random topology if the program has to decide where to put the topology. The more random topology can create some bad shadows/highlights, so you'll often want to fix those areas by making sure there's only quads (and occasional "loose" tris if it can't be avoided) in the mesh before exporting. If you make a mesh from scratch, use quads. It lets you mesh a whole lot more easily than tris does, and you don't need to worry too much about the tris. Just make sure to keep a copy of the version with quads for if you have to make adjustments.
There are some ways around the tris issue in Blender, but it depends what you're planning to do to a mesh. You can remove the tris (to some degree, anyway - it's not a perfect method) by marking the mesh and using alt+J. Some fixing is most likely required, and it occasionally removes the wrong lines, so it can be an idea to remove the tris in stages, or just in areas you want to change.
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Post by mauvemorn on Dec 17, 2021 8:25:04 GMT -5
Hi. Just to make it clear, the meshes are triangulated in all games because no matter where in space three vertices are, they will always create a flat surface that can be shaded only one way.  When you import a mesh in s4s, it is triangulated for that reason. More about it here
However, people model in quads because they are more manageable. When the mesh is in tris, you cannot select an edge loop, cannot get good topology when subdiving, will get unnecessary vertices when inserting edges, and so on.  That said, tris are not the key to good topology, it's good edge flow. If you have good edge flow, it will look the same whether it is in quads or in tris. See how badly the mesh is shaded along the folds? If the edges went along the folds, it would have been smooth  |
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Post by pandamontok on Dec 17, 2021 16:34:30 GMT -5
Thank you for all of your answers.
Let me try to understand them.
So, the reason game engines turn designer quads to tris is because
mathematically tris are the easiest form to calculate. The coordinate of the three points of a tris always create a flat surface, thus use less computing power. While quads could potentially create more complex stuff than it should, thus demands more power.
We human uses quads in topology because it's much easier to manage and control.
And by using a good edge flow, we'll have better shading.
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