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I'm asking myself if using quads is really the better practice instead of using ngons (for flat surfaces!) when it comes to game modeling.

I often read this and saw models that look like this (96 tris!). enter image description here

But I can't understand why this should be preferred instead of this model using ngons (60 tris!) enter image description here

Are there reasons why the quad variant with more tris should be preferred also for a final game model (that also does not use displacement mapping for example) or is the n-gon actually preferred in such cases because of the lower triangle count?

Because it came up in the discussion: This should be of course only valid for static objects that do not deform, my question came up because I saw that models which are most likely not supposed to deform are modelled using the additional quads and I'm wondering if there's really any benefit of doing it (I just see the disadvantage of additional triangles so far).

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    \$\begingroup\$ Ultimately, the GPU draws triangles, so you should use triangles. And if I'm not mistaken, if you can manage to make your triangles as a triangle strip, you could reduce the size of your draw calls with OpenGL. \$\endgroup\$ – Vaillancourt Apr 16 '16 at 13:53
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    \$\begingroup\$ @AlexanderVaillancourt the question indicates that the asker is already aware of the fact that the model is ultimately rendered as triangles. (Note the triangle counts) The question is whether additional vertices should be inserted to ensure a rectilinear topology (this is commonly recommended for models that need skinned animation or deformation — arbitrarily triangulated polygons can collapse or intersect in visually unappealing ways under these operations) \$\endgroup\$ – DMGregory Apr 16 '16 at 18:53
  • \$\begingroup\$ Please don't use the term 'tris' to refer to the count of n-gons, even if your modelling tool or field does. The dissonance made the question harder to read than it should've been. \$\endgroup\$ – Lars Viklund May 17 '16 at 7:51
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There is never an N-gon in any model for a game. All graphics cards use triangles. N-gons are a software construct in 3D apps. When you model for games you should always use triangles or get rid of N-gons. I use Cinema4d and it has some good tools for that. Blender does also. If you do not triangulate your model, the end-user game engine or importer will try and do so on its own and this can be problematic. Worst case is your models look bad.

TL;DR - N-gons are never used by GPUs. Use triangles.

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  • \$\begingroup\$ Reproducing this mesh gives me 72 verts in Cinema4d using both quads and ngons. Both models have the same cost in Assimp. My Blender skills are not very good but i'l try it in the morning. Using triangles in C4d though I get only 56 verts. \$\endgroup\$ – zimspy Apr 16 '16 at 22:49
  • \$\begingroup\$ It might be worth covering that a triangulation scheme may not be quite capable of creating triangles that properly consider attributes such as texture coordinates. Most literature I've seen only deals with positions. \$\endgroup\$ – Lars Viklund May 17 '16 at 7:54
  • \$\begingroup\$ "There is never an N-gon in any model for a game." - I would not be so categorical. E.g. I have N-gons in my game. \$\endgroup\$ – Kromster says support Monica Jul 23 '16 at 16:31

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