Bent faces and triangles?

[GamesWithAnthrosFTW]

I am taking CG Cookie courses and from what I learned so far, faces must be quads.

Do faces need to be quads?
Also, are bent faces OK?

[Radical Left Lunatic]

That's nonsense faces can be made from any group of points of at least three. Faces can be bent how ever you like stretched between a group of points. Think of a face like a canvas stretched tight, nailed on to pegs of varying heights, the pegs are the vertices and the canvas is the face.

[Zenogias]

Well,I think you misunderstood something,Face should be quad but it does not mean you can not use triangle or anything else.

I am not so sure what do you mean about Bent face as well,but I think it means Bent modification.

Sure you can use you all of them,what's the point of creating a function that's not supposed to be used.

Quad is your best friend but that does not mean you don't need the other friends.That's what I can tell you.

Quad is supposed to be the main mesh but at some point or some part you also need the others type of primitive as well.

[Basho]

you dont have to use quads. however:

quads are preferable because different methods of smoothing (such as subdivision suface) can get weird if you are not using quads.
also, it gets even more complicated because different software will handle things in different ways, so sticking to quads can minimize cross-software complications.
i suspect texturing and animation can also be an issue at times, especially in combination with all the above.

in addition to problems with tris (triangular faces), the same also goes for n-gons (faces with more than 4 vertices), they can really mess things up at times.

that said, it all comes down to what your intentions are, and how the model is going to be used. it is considered good practice sticking to quads, so it is a good idea to keep that in mind and try to minimize the cutting of corners so to speak.
but as long as no problems arise then there is nothing that says you must always use quads. just know that it can mess you up down the road if you are careless.

also, bent faces are okay but for similar reasons to the ones described above, you may want to keep them to a minimum and instead try to bend the mesh along edges/seams as much as possible.

[Radical Left Lunatic]

Originally posted by Basho:

you dont have to use quads. however:

quads are preferable because different methods of smoothing (such as subdivision suface) can get weird if you are not using quads.
also, it gets even more complicated because different software will handle things in different ways, so sticking to quads can minimize cross-software complications.
i suspect texturing and animation can also be an issue at times, especially in combination with all the above.

in addition to problems with tris (triangular faces), the same also goes for n-gons (faces with more than 4 vertices), they can really mess things up at times.

that said, it all comes down to what your intentions are, and how the model is going to be used. it is considered good practice sticking to quads, so it is a good idea to keep that in mind and try to minimize the cutting of corners so to speak.
but as long as no problems arise then there is nothing that says you must always use quads. just know that it can mess you up down the road if you are careless.

also, bent faces are okay but for similar reasons to the ones described above, you may want to keep them to a minimum and instead try to bend the mesh along edges/seams as much as possible.

Actually wouldn't triangles insure maximum cross platform compatibility? After all you cant even render a quad in DX, you have to use two triangles instead(OpenGL does have a primitive quad mode, also i guess you dould draw a quad by setting the primitive topology in DX to line but then you would only see four lines and line mode is meant for debugging any ways). I always triangulate faces before exporting to any format becuase its the safest option and works everytime.

[Scre]

Actually wouldn't triangles insure maximum cross platform compatibility? After all you cant even render a quad in DX [/quote]

Not sure what is DX but am sure with cross platform he ment Unity and Unreal Engine.

Wich get converted into triangles when u export to FBX.


But to answer the OP questions best to have quads in Blender for animation and smoothing purpose especialy when a mesh "bends"

If u have a mesh that is bended best to divide it, or bevel it.

Here is something that helps u model without mistakes so u can Bake the normals, might be handy.
http://leonano.com/portfolio/2-not-more-wrong-normal-map/

[still__alive]

I think this might be what he means by "bent" faces:

http://steamcommunity.com/sharedfiles/filedetails/?id=784998881
http://steamcommunity.com/sharedfiles/filedetails/?id=784999289

Might be hard to tell, but that selected face is 1 quad with a couple verts pulled back so that when you view it from a certain angle it appears as if it is a tri instead of the quad. It is pretty extreme but it's a quick example of what I think DiamondDrone means by a "bent" face. If it is, then I would guess bent faces are bad and would probably cause shading issues or something.

Originally posted by zoomdude111:

Actually wouldn't triangles insure maximum cross platform compatibility? After all you cant even render a quad in DX, you have to use two triangles instead(OpenGL does have a primitive quad mode, also i guess you dould draw a quad by setting the primitive topology in DX to line but then you would only see four lines and line mode is meant for debugging any ways). I always triangulate faces before exporting to any format becuase its the safest option and works everytime.

As I understand it, you can feed a mesh with quad topo into a game engine or whatever, and the mesh will be automatically triangulated. However, leaving that up to the GPU or game engine could result in issues like shading artifacts or stretched textures. So a good practice would be to do your modeling with good topo and quads and then triangulate it before exporting depending on where you are using it. If it's going to be used in a game engine, triangulate it - if it's going to another 3d app then leaving as quads is probably fine or better.

Probably the biggest reason to use quads is because they give you the most control over how your topology flows. A mesh with good topology is much easier to work with, will animate better, be easier to unwrap, and should texture better too. And like Basho said techinques like subdivision surface modeling don't work well with triangles or n-gons because they divide poorly resulting in shading issues.

[Radical Left Lunatic]

Originally posted by Scre:

Actually wouldn't triangles insure maximum cross platform compatibility? After all you cant even render a quad in DX

Not sure what is DX but am sure with cross platform he ment Unity and Unreal Engine.

Wich get converted into triangles when u export to FBX.


But to answer the OP questions best to have quads in Blender for animation and smoothing purpose especialy when a mesh "bends"

If u have a mesh that is bended best to divide it, or bevel it.

Here is something that helps u model without mistakes so u can Bake the normals, might be handy.
http://leonano.com/portfolio/2-not-more-wrong-normal-map/ [/quote]
I could not get an fbx model working correctly in unreal engine or unity without first triangulating all the faces. Also faces do not get put into triangles automatically when you export to fbx. By DX I meant direct x(I only use 11 and 12, so I am not sure about older versions).

[Scre]

Originally posted by zoomdude111:

I could not get an fbx model working correctly in unreal engine or unity without first triangulating all the faces. Also faces do not get put into triangles automatically when you export to fbx. By DX I meant direct x(I only use 11 and 12, so I am not sure about older versions).

U prob messed up your settings when exporting to unreal.
u can open .blend files with Unity if u save them in the correct Unity map.
I never had any problems, that said i never animated afhter importing.

Blender has also a Modifier (Triangulate) wich converts the meshes into triangles.
Maybe good to know and try before exporting :)

Still not sure how u open a blender file with DX ;)

Originally posted by still__alive:

I think this might be what he means by "bent" faces:

http://steamcommunity.com/sharedfiles/filedetails/?id=784998881
http://steamcommunity.com/sharedfiles/filedetails/?id=784999289

Might be hard to tell, but that selected face is 1 quad with a couple verts pulled back so that when you view it from a certain angle it appears as if it is a tri instead of the quad. It is pretty extreme but it's a quick example of what I think DiamondDrone means by a "bent" face. If it is, then I would guess bent faces are bad and would probably cause shading issues or something.

This also what i was thinking and said best to divide or Bevel them.

[Radical Left Lunatic]

Originally posted by Scre:

Originally posted by zoomdude111:

I could not get an fbx model working correctly in unreal engine or unity without first triangulating all the faces. Also faces do not get put into triangles automatically when you export to fbx. By DX I meant direct x(I only use 11 and 12, so I am not sure about older versions).

U prob messed up your settings when exporting to unreal.
u can open .blend files with Unity if u save them in the correct Unity map.
I never had any problems, that said i never animated afhter importing.

Blender has also a Modifier (Triangulate) wich converts the meshes into triangles.
Maybe good to know and try before exporting :)

Still not sure how u open a blender file with DX ;)

Originally posted by still__alive:

I think this might be what he means by "bent" faces:

http://steamcommunity.com/sharedfiles/filedetails/?id=784998881
http://steamcommunity.com/sharedfiles/filedetails/?id=784999289

Might be hard to tell, but that selected face is 1 quad with a couple verts pulled back so that when you view it from a certain angle it appears as if it is a tri instead of the quad. It is pretty extreme but it's a quick example of what I think DiamondDrone means by a "bent" face. If it is, then I would guess bent faces are bad and would probably cause shading issues or something.

This also what i was thinking and said best to divide or Bevel them.
:emofdr:

I never said i opened a blender file directly with DX, i usually load from .obj or .fbx models since .blend files are quite complicated and obj or fbx files are easy to read and parse. What i said was DX does not render quads as a primitive topology, its not possible. You could of course create a triangle topology from a geometry shader of course but its easier just to triangulate them in blender before hand.

[phillippi2]

You should always use quads when making organic models (such as characters, grass, etc) because quads give you better control of something called Deformation. That is, how the object changes shape when it's moved. A good example you can test yourself is by watching the inside of your elbow when you bend your arm, or the various parts of your leg when you bend them.

The computer has to move the polygon based on the average direction that it's facing. Triangles direct all the deformation towards a center point, while N-Gons distort the shape in unpredictable ways. Due to rendering API's (Blender uses OpenGL, but tells it to use the CPU, except when using Cycles) the renderer splits the quad into two triangles (in the case of N-Gons, they're first split into a mixture of quads and triangles, then the quads are triangulated) Because of this, non-flat quads have the same effect as triangles; forcing the deformation towards a single vertex.

[tripmix]

Animators will hate you for using tris over quads it depends on the scene really if you can get away with triangles and that works for your scene go ahead and do it he's just trying to get you in a good habit of using quads but unless the mesh is going to be animated, its not a requirement merely good practice.

[AN BIFFED ELF!!!!]

Real-time 3d will always use triangles though and Blender sometimes has very bad choices in automatic quad->tri splitting having requiring of some edge turns after the fact.