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Thread: Triangles are BAD, mmmkay?

  1. #1
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    Triangles are BAD, mmmkay?

    I need opinions from people who work with 3D character models and it's even more helpful if you animate your 3D models. I have created a 3D mesh of a female character (nude, no clothes or hair) and will have 8 triangles in the mesh once I mirror it.

    Any suggestions or advice or should I quit worrying? The triangles are -

    1. behind the ear
    2. at the corner of the upper lip
    3. at the ankle behind the outer ankle bone
    4. in the inner wrist
    "Once one can articulate an important idea into a concise statement, then one can use the statement and not have to have the fear of changing behavior." - Ed Catmull on Pixar creativity

  2. #2
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    Freeze model, with wireframe solid mode in perspective viewport. If you see that sub-patch triangle messed up polygon flow, you should undo and fix. There are places where triangles are completely fine and fitting in polygon flow perfectly. You will see these places in temporary frozen mesh.

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    Thanks Sensei. I will check. I have made character models only a few times before and want to get this one right.
    "Once one can articulate an important idea into a concise statement, then one can use the statement and not have to have the fear of changing behavior." - Ed Catmull on Pixar creativity

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    Worked great! THANKS.
    "Once one can articulate an important idea into a concise statement, then one can use the statement and not have to have the fear of changing behavior." - Ed Catmull on Pixar creativity

  5. #5
    Triangles are fine to use but if you can get rid of them easily, you should. Concerning placement, the only one I would change for sure is the one at the corner of the mouth. My rule for placement of triangles is anywhere where there won't be any significant deformation. The mouth is not one of those places.

    Just some areas I usually have a triangle if anywhere- back of the ear, top of the head (as long as there's hair covering it), inside mouth, eye, ear, or nose cavities, and any flatter area of the mesh that won't see any or much deformation.

    You should also consider whether you will be UV mapping it. I've found it can often be harder to fix distortions in texture mapping with triangles. Again, places where they won't be visible are ideal.

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    Thanks hr. I plan to UV it.

    Is it possible to UV a frozen Sub-D mesh?
    "Once one can articulate an important idea into a concise statement, then one can use the statement and not have to have the fear of changing behavior." - Ed Catmull on Pixar creativity

  7. #7
    Quick demo of something i'm working on. Correct me if I'm wrong, as usual (seriously). Verbose Mode [ON]

    I suppose you are using subdivision so, topologically speaking in subdivision a triangle is the same as a point with 3 edges (3-edged-pole). Meaning, when you freeze the subdivision on both, they will look the same: Both will end in a 3-edge-pole.

    What do they differ? Well with subdivision triangles you get more more control points that will influence the end position of the resulting pole; 3 points (triangle) + 9 (neighbours) , while with the subdivision pole, you get 1 (pole) + 6 (neighbours). So, it can require more work to control the final result with the subdivision triangle since you have 12 points to edit and tweak, instead of the 7 of the subdivision pole.
    On the other hand if you use a poleless mesh deformations and spring calculations might be more consistent since every vertex has 4 edges pushing it around (needs testing, shooting wild guess here.)

    Control Points comparison


    A thing to consider about -all quads- or no -poles meshes- is the type of selection that will be more relevant for the modeling operations. One will give uninterrupted Edge Loops and the other will give you uninterrupted Face Loops. Normally selecting Face Loops is more important, i guess.


    It won't be in exactly the same place but you can convert a triangle to a 3-edge pole easily by adding or removing an edge. Well, if you have the precise amount of edges needed to define your shape probably no reason to convert one into the other.


    Cheers
    Last edited by probiner; 07-04-2011 at 06:22 PM.

  8. #8
    Quote Originally Posted by rcallicotte View Post
    Thanks hr. I plan to UV it.

    Is it possible to UV a frozen Sub-D mesh?
    Sure, but you won't want to. Normally UV's requires quite a bit of adjustment depending on the situation. A frozen mesh is going to have a ton more vertices and just like modeling, the denser a mesh is, the harder it is to work with as you'll go blind pushing points around all day. Better to UV it first, get them the way you want and then if you feel the need to freeze it (not sure why you would), your UV's will be retained.

  9. #9
    Pixel and Poly Pusher JeffrySG's Avatar
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    Quote Originally Posted by probiner View Post
    Quick demo of something i'm working on. Correct me if I'm wrong, as usual (seriously). Verbose Mode [ON]
    Great stuff as always, probiner!

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    @probiner - Wow. Okay. Makes sense and probably isn't as easy as it looks on paper. If only my mesh could have open borders, this would be so much simpler. Something to consider when I do this again. Thank you. This helps to better think through this process.

    @hr - Right. Dense mesh. Okay. I'll see what comes of a UV before freezing, if I ever need to freeze the mesh for export (are there other reasons?).
    "Once one can articulate an important idea into a concise statement, then one can use the statement and not have to have the fear of changing behavior." - Ed Catmull on Pixar creativity

  11. #11
    World's Tallest Dwarf safetyman's Avatar
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    Quote Originally Posted by JeffrySG View Post
    Great stuff as always, probiner!
    :agree:

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    Registered User Dreamcube017's Avatar
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    Question. I know triangles are not good, but when working with game models and reduced meshes (reduced INTO triangles) then what whould we do? Even if we DO make the mesh with all quades, the game engine itself just slices those in half. So then what? What would be the workflow here?
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  13. #13
    Question. I know triangles are not good, but when working with game models and reduced meshes (reduced INTO triangles) then what whould we do? Even if we DO make the mesh with all quades, the game engine itself just slices those in half. So then what? What would be the workflow here?
    Realtime objects are the exception, but you will probably not use Subpatches to mode those anyway, unless you are planning on using DirectX 11 and even then, I think they currently use SubD methods that work better with triangles.
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  14. #14
    "Indie" Game Artist GandB's Avatar
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    Best thing to do when making game media; is to save the LW or similar format to retain the quads, then triangulate and save a separate .X model (for example).
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  15. #15
    Quote Originally Posted by rcallicotte View Post
    @probiner - Wow. Okay. Makes sense and probably isn't as easy as it looks on paper. If only my mesh could have open borders, this would be so much simpler. Something to consider when I do this again. Thank you. This helps to better think through this process.
    Open borders are good to waste edges. But if you waste edges in pairs they meet each other close. Like in Jeffry's stepping tabble where you have an edge waste from 2/1 column to the other 2/1 column. They meet and close on each other. Same thing is done with triangles and n-gons. (those 2/1 steppings are basicly 2/2, but 1 of them is wasted to the side)



    But that's why I said, if your shape doesn't get better by cross adding/removing edges, it's probably more trouble to force all quads than go with triangles. Since most of the times you add/remove edges to an already established shape in SubD you have to tweak the mesh distribution, to reconstruct the shape and it's smoothness. And with the current subD-blind tools that can be extremely tiresome to do all day.

    Glad it helps you think. Cheers
    Last edited by probiner; 07-05-2011 at 01:10 PM.

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