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Two different vertices count


Apple Pumpkins
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I've made an object in 3DS Max to upload. In 3D Studio Max, the triangulated mesh shows as 2,928 vertices. However in the uploader it shows as 4,550 vertices, and is calculating 14 prims. The object is no larger than a 1M square bounding box.

Is this an error anyone else has experienced?

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the vertex count as calculated by the mesh importer is more complex than it may look in first place.

 

  • It first counts alll vertices just like you expect (and like your 3D modelling software shows you),
  • If you have used seams (and you most probably HAVE used seams), then you get additional UV vertices, because at the seams the UV-vertices are doubled and such need extra space.
  • If you use flat shading instead of smooth shading, i believe that each vertex which belongs to a flat shaded face gets counted as many times as it is shared by other flat shaded faces. this is because with flat shading the importer needs to store the vertex normals according to each adjacent face. (I must admit that this explanation is a guess and if its wrong, please can anyone correct me ?)

Hence the displayed number of vertices in the mesh importer can be significantly higher than the number of vertices shown in your modelling software (which only counts the actual number of vertices)

 

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Oh wow, a lot more goes on than what i would've thought. :) I took the risk of reducing my highest LOD in the uploader, and it went straight down to the correct poly size from 4.5k... but there's no apparent reduction on the mesh. I managed to get it down altogether to 9 prim equivs, but I guess is that a lot for an object such as this?

finishedbureau.png

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Gaia is right. Have a look at this diagram. In the internal format, each vertex has postion, UV coordinates and a normal vector. If the normal or the UV coordinates differ, the whole vertex has to be replicated even though it has the same position. So UV seams and sharp edges make more vertices as far as SL is concerned. It also has to be replicated in each material (submesh) on the faces it touches.

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Hey, that looks awesome ;-)

One question though: How did you "reduce" the high LOD ?

regarding vertex count: I suspect that most of your vertices are used in the rings of the drawers ? The cabinet itself should not take more than about 100 quads (~200 tris).

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Thanks Drongle, maybe I'll have to keep this in mind when I make my UV maps from now on. Although I don't use automatic unwrap or flatten map or stuff like that, I do do it properly, I'll just have to be more... economical :P In future.

And thanks Gaia :) Yes most of the poly's are in the handles :D I reduced the high LOD using the uploader thing. I only clicked the down arrow once and it trimmed those extra vertices right off, so unless that is a glitch I'm unsure what I actually did. :P

I am used to low poly modelling for other games, but seeing some of the beautiful smooth meshes on the marketplace already I figured I wouldn't have a cat in hells chance if I carried on along the same path here on SL :) But reducing the handles is something I'll probably end up doing.

 

Edit: Just noticed how much yellow is in this post. Need to cut down on smilies... :D

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Upon re-importing my exported collada file back into Max, it seems that although my UV map hasn't moved, all of the vertices have been unwelded and may have been the cause of the glitches.

Also, I managed to reduce the handles without them looking too blocky, and the object now sits at 1.4K poly's 4 prims.

Thanks everyone :D Kudo'ed all of your posts.

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