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Question about polygons

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I taught myself how to model mesh (using 3DS max) as a result I have learned lots of useful skills specifically pertaining to creating mesh for SL but I also have gaping holes in both my knowledge and skillset in the general field of 3D modeling.

Something I learned early on was that for mesh in SL every poly needs to be a quad with 4 sides and we should not use 3 sided triangular poly's for mesh. I have no idea where I learned this, I could have just made it up for all I know, but whatever the source, it is now restricting my work. So, should I only be using quads? If so why? And Isn't a quad essentially made up of 2 triangles anyway?

Thanks.

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There is absolutely no need to work in quads for SL.

The reason most models you'll see on sale are made out of quads is that quads are easier to modify, both by your software and by yourself. If you have a full quad model you can subdivide very smoothly for example. A clean topology also lets light bounce off more lifelike and smooth.

For a final model however you can have triangles, in many cases they will save a ton of geometry, which should be the focal point for a platform like SL. Try making a cylinder cap with quads, it can be done, but it will take a lot of unnecessary vertices in a flat plane.

I'd say avoid loose triangles and use quads where you can to keep a clean topology, but in some cases triangles are simply the better choice.

And yes a quad is always two triangles.

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Right, Quads have benefits during the modelling process. 

However, once in SL, all objects are 'converted' (triangulated) to being made of triangles. 

You can see this in SL by enabling wireframe mode (CTRL+SHIFT+R)...no Quads, only Trianles there.

Finally: if you model in Quads, you might want to know how your model will look in SL after beeing triangulated. You can achive this in 3dsMax by going into the object's properties, and there uncheck 'Edges only'. Afterwards you will see the 'invisible' edges that divide your Quads into Tris. 

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Marielle Caerndow wrote:

 

Finally: if you model in Quads, you might want to know how your model will look in SL after beeing triangulated. You can achive this in 3dsMax by going into the object's properties, and there uncheck 'Edges only'. Afterwards you will see the 'invisible' edges that divide your Quads into Tris. 

Since you mention that, if the object is an editable poly, you can change the direction of that dividing line in a quad by selecting the polygon then clicking retriangulate.

btw, are you 100% sure this will show the triangulation the same way it will be in SL? I think I remember the Blender folks having to triangulate before export to have control over the final triangulation in SL. Isn't the same the case for any other 3d program?

 

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Yes, editing the triangulation is possible. Actually there is your way, and another one: on EditablePolys or EditableMeshes (or Poly/Mesh-modifier), when going into Edge-subobject mode there's a button 'Turn'. This lets you turn a clicked edge.

On EditeblePoly (or Edit Poly Mod), the turn-command works only on the invisible edges (which can be viewed as described above).

On EditebleMesh (or Edit Mesh Mod), the turn-command works on all edges, visible and invisble ones.

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About beeing same in Max and SL: it depends. Sometimes on export the error-window opened with a message like "Exporter has detected turned edges and the object has been triangulated/converted to editable mesh" (if the option to show the error window is active).

To my knowledge it means that the exporter didn't like the objects existing triangulation/topology, and thus applied changes - here the result in SL might be different to what's in Max.

Otherwise I had no issues, triangulation was same in Max and SL. (Btw, exporting directly from Max 2011, not using the FBX-converter)

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Marielle Caerndow wrote:

Btw, exporting directly from Max 2011, not using the FBX-converter

Another thing there:)

Can anyone using 3ds max 2012 confirm the 2013.2 exporter doesn't need the workaround with fbx? It works for 3ds max 2013 and I'm not rolling back just to check this.

 

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So to clarify....I have spent the past 18 months creating mesh, all the while working under a self imposed rule that is not even relevant to SL. and which has potentially restricted the efficiency of all my imported models.

I suppose at least I have asked the question now, even if I do feel like a complete plonker.

I am my own worst enemy. Thanks very much to both of you :matte-motes-big-grin:

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Since you mention efficiency, keeping your models quad-based while working on them is quite good for efficiency. Only on quad-models you can quickly select an edge-loop or a ring-selection - handy for refining or reducing towards lower LODs (in case you hand made them).

 And like Kwakkelde mentioned, Subdivision is smoother on quad-models. So, quads are handy, but not the holy gral :-).

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In Blender 2.49, you can get triangulation three ways, triangulte in Blender, triangulate in the collada exporter, or let the uploader triangulate (it will not upload quad data). They will all give different results whch can affect shading if the quads are not flat. So the only way to control it precisely is to triagulate in Blender before export and adjusty that if you need to. That can be VERY tedious. I guess in 2.6 etc, the collada exporter uses the Blender triangulation, but you still have to do it first if you want the opportunity to adjust it.

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I normally always build in quads as it's just easier to maniluplate and to select loop and ring edges etc, however sometimes I want to smooth or use a Pro Optimiser to lower the weight which results in the triangles I have been trying to avoid up to now. This revelation is definitely going to help!

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Kwakkelde Kwak wrote:


Marielle Caerndow wrote:

Btw, exporting directly from Max 2011, not using the FBX-converter

Another thing there:)

Can anyone using 3ds max 2012 confirm the 2013.2 exporter doesn't need the workaround with fbx? It works for 3ds max 2013 and I'm not rolling back just to check this.

 

The 2013.2 fbx plugin for max 2012 still doesen't work for SL. Although  multi-materials are imported now, the UV's are completely messed up.

Edit: I'll take that back, just tried it again with a simple cube with 3 materials and all came in fine. Materials and UV's with the 2013.2 fbx plugin exported from Max 2012.

 

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Thanks for confirming, that's what I suspected. There's a catch though.

You can't use objects with spaces in their names, that will give an error on upload. Others have noticed the same for materials and textures, although I'm pretty sure I managed to upload a model with a space in the material name.

Anyway, better safe than sorry and avoid spaces altogether.

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I have another question about polygons.

Is it possible to create a plane (using 3DS Max) and then apply/map a material to both sides? At the moment when I create a plane it only has 1 face, flipping the normal's will switch the direction of the face but still leave me with only 1 face to texture. I can see in the materials editor that there is a check box for "2-sided" but it seems to have no affect. I've also tried the cull backfacing option but that just makes the back face invisible. Thanks

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In Max you can achive different materials on the front and back of a face (by using the "Double Sided" material).

But in SL the polys will always be single-sided. Thus the only way to make objects 'solid'/2-sided for SL will be to really create the backside (on complex models the "Shell"-modifier is handy).

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Yeah, I can manage to get both faces to show up when rendering in Max but no luck importing into SL. I have used the shell modifier before and other work arounds that do the job. I was just wondered if I was missing something obvious as was the case in my opening post. Thanks allot :matte-motes-big-grin:

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Marielle Caerndow wrote:

Since you mention efficiency, keeping your models quad-based while working on them is quite good for efficiency. Only on quad-models you can quickly select an edge-loop or a ring-selection - handy for refining or reducing towards lower LODs (in case you hand made them).

 And like Kwakkelde mentioned, Subdivision is smoother on quad-models. So, quads are handy, but not the holy gral :-).

Once I have completed all modeling and mapping in Max, is it advisable to then convert all the quads to tri's in Max or should I just let SL triangulate it on upload? I am guessing doing it in Max would be better as I can tweak it, but just wondering if it is worth the effort. Up to now I have been uploading mainly quads and have been happy enough with the results.

Also is there a simple process in Max to triangulate all the poly's?

Cheers.

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As mentioned earlier, when you export directly from Max the the triangulation (especially orientation of the invisible edges) remains the same in SL. In rare cases Max's exporter gives a warning when it changes the edge orientation - and if you go over additional tools (like the fbx-converter) it migt also be changed.

If you triangulate in Max, the edges should definitely remain oriented as they are. (I would still only do it if necessary.)

A simply way that comes to my mind: apply an EditableMesh modifier, go into the edge-sub mode, select all edges (it should also select the invisible edges) and finally look in the command panel. Somewhere in the EditableMesh modifier is a button named 'Visible', which converts all edges to 'visible' edges.

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