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Blender LOD texturable faces issue


Brick Swansen
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I am losing my mind on this one.  I have a Blender LOD issue maybe someone can help with. I cannot figure it out.  I have a Blender model with two objects. Each object was created by joining several objects. One of the two is made up of several pieces that were sculpted with the sculpt tool. So the problem. I get the "LODs have a different # of texturable faces" error on my first decimation (Medium LOD).  There are only 2 materials in the whole thing, one for each object. I have created my own LOD models using the decimate modifier, and even tried only a slight decimation. Still got the error. Yes, there are only two materials in the model, one for each LOD, and with each LOD there is at least one face with the material applied. I have tried renaming the dae files.  There are only one UV map for each object. What else can cause this? I'm going crazy here. 

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5 minutes ago, Brick Swansen said:

I am losing my mind on this one.  I have a Blender LOD issue maybe someone can help with. I cannot figure it out.  I have a Blender model with two objects. Each object was created by joining several objects. One of the two is made up of several pieces that were sculpted with the sculpt tool. So the problem. I get the "LODs have a different # of texturable faces" error on my first decimation (Medium LOD).  There are only 2 materials in the whole thing, one for each object. I have created my own LOD models using the decimate modifier, and even tried only a slight decimation. Still got the error. Yes, there are only two materials in the model, one for each LOD, and with each LOD there is at least one face with the material applied. I have tried renaming the dae files.  There are only one UV map for each object. What else can cause this? I'm going crazy here. 

Are you trying to upload as a linkset? Rather than singly?  If so there are certain rules that you need to follow in the naming and that might be your issue. I don't ever do that so I don't remember the naming. You will also need two different physics models.

Unless you REALLY need to upload your model as a linkset, I suggest at least trying to upload them singly and see if that works.  If they upload singly OK, then it is the naming issue and one of the folks that knows that can help you out. 

The decimate tool is often NOT your friend by the way LOL. Sometimes handy but sometimes grievous issues.  I doubt that is your problem here though. 

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1 minute ago, Chic Aeon said:

Are you trying to upload as a linkset? Rather than singly?  If so there are certain rules that you need to follow in the naming and that might be your issue. I don't ever do that so I don't remember the naming. You will also need two different physics models.

Unless you REALLY need to upload your model as a linkset, I suggest at least trying to upload them singly and see if that works.  If they upload singly OK, then it is the naming issue and one of the folks that knows that can help you out. 

The decimate tool is often NOT your friend by the way LOL. Sometimes handy but sometimes grievous issues.  I doubt that is your problem here though. 

Thanks for the reply.  I guess it does upload as a linkset, with the 2 objects becoming links. I've had no problems with that in the past. I'm only naming the LODs with a "M" or "L" added to the end of each new LOD.  Please tell me the alternative to the decimate modifier. You're the second person to tell me that, so now I am curious.

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43 minutes ago, Brick Swansen said:

Thanks for the reply.  I guess it does upload as a linkset, with the 2 objects becoming links. I've had no problems with that in the past. I'm only naming the LODs with a "M" or "L" added to the end of each new LOD.  Please tell me the alternative to the decimate modifier. You're the second person to tell me that, so now I am curious.

As I said I don't know the naming exactly but you have to identify each piece with LOD2  etc. I am sure this has been discussed many times on the forums so a search with "LOD naming" will probably give you that info.

I don't make my own LODs (at least not usually) but what I make doesn't call for it usually (also my opinion on that :D ). You can remove edgeloops, merge vertices and the like to make your LODs. Again, a search of "making LODs" will likely give you some ideas. You can also make low poly mesh which is what some of us aim for here *wink* where dire changes aren't needed for the LODs ^^. 

Sure others will reply. Weekends are typically slow on the MESH Forums. I suspect folks read during their lunch break or whatever. I read during long bakes LOL.

 

Good luck!

 

 

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16 minutes ago, Chic Aeon said:

Good luck!

 

 

Thank you Chic.  Yeah I probably shouldn't spend my weekends at this either, lol. But so I got it to work. You made me consider the polys, so I just decimated it at 50% for the highest LOD.  It was pretty high poly.  That worked. All lower LODs generated from the decimate mod came in fine after that. Makes me wonder how people make such intricate avatars and things like that with low poly mesh. Any suggestions? Because I lost a lot of detail.

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Well the decimate tool is only needed when you go overboard. You need to learn how to make mesh that is for GAMES. There are also limits to the amount of vertices you can upload in Second Life. I didn't even THINK about that issue.

Most importantly you need to know that many to most "how to" videos for blender are NOT about GAME ASSETS which is what we make here. Think about making something with the least amount of vertices you can. Don't just follow along with a tutorial that is actually based on a RENDER as the final project. Whole different thing. 

And depending on the settings in decimate you can end up with a lot of "air" and some very nasty combined vertices, so much better to model  from a cube or whatever. High density sculpting "can" work here but you really need to know what you are doing to make something that is anywhere near close to optimum. 

 

Good luck. 

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13 hours ago, Chic Aeon said:

Well the decimate tool is only needed when you go overboard. You need to learn how to make mesh that is for GAMES. There are also limits to the amount of vertices you can upload in Second Life. I didn't even THINK about that issue.

Most importantly you need to know that many to most "how to" videos for blender are NOT about GAME ASSETS which is what we make here. Think about making something with the least amount of vertices you can. Don't just follow along with a tutorial that is actually based on a RENDER as the final project. Whole different thing. 

And depending on the settings in decimate you can end up with a lot of "air" and some very nasty combined vertices, so much better to model  from a cube or whatever. High density sculpting "can" work here but you really need to know what you are doing to make something that is anywhere near close to optimum. 

 

Good luck. 

Hey thanks again. I appreciate your insight. I have been learning from online videos, and there are lots of resources, but I will try to keep that in mind a little better. Highly detailed organic modeling may need to become something different than the vision in my head ;).

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Slightly off topic.  I am thinking of using a high-poly (yeah, with subsurf and everything) model to bake onto a much simpler High-LOD scaled version.  This seems to me to be the only rational use of a high-poly model in blender for SL.  In effect it is using the detail of the high-poly to create detail in the texture - this then gets applied to the High, Med, Low, and Lowest LOD models via the High.  This way, there is some mileage in watching those lovely Blender Guru tutorials.

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On 2/25/2018 at 2:25 AM, Brick Swansen said:

All lower LODs generated from the decimate mod came in fine after that. Makes me wonder how people make such intricate avatars and things like that with low poly mesh. Any suggestions? Because I lost a lot of detail.

The problem sits in the assumption that every single detail should be modeled, when game assets, by definition, can't afford that grade of geometric detail. For this reason, normal maps play a huge role in such regard, catching the high res surface details in a map to be applied on a lower resolution object. Add your textures and, along with their colors, generate a normal for them to blend on top of the object's normal map, the one extracted from the high res model. You can use the final normal map on your object's material and bake all the shading effects onto the color map for SL, if you don't want to use SL materials (normal, glossiness, specular and environment maps)

Edited by OptimoMaximo
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5 hours ago, anna2358 said:

Slightly off topic.  I am thinking of using a high-poly (yeah, with subsurf and everything) model to bake onto a much simpler High-LOD scaled version.  This seems to me to be the only rational use of a high-poly model in blender for SL.  In effect it is using the detail of the high-poly to create detail in the texture - this then gets applied to the High, Med, Low, and Lowest LOD models via the High.  This way, there is some mileage in watching those lovely Blender Guru tutorials.

Actually I think that is ON topic really and might work for the OP.  I did that a few times in Opensim (some discussions there on the Google group prompted me). It worked well, but not really my style of products so haven't done that in awhile. That method can give a "normal map" look on objects without using the normal map (which not everyone can see). You can also MAKE a normal map and then use that as displacement in your node setup -- so another option to try :D. 

Edited by Chic Aeon
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I hadn't even considered normal maps, mostly because of the fact that they mostly go unseen. But there are plenty of people looking for quality products who will have graphics set appropriately in order to see the quality I'm sure.  But the idea of using the baked images from higher poly models could be a great solution here for all of it.  Thanks guys!  Will experiment.

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Addressing the initial problem of the OP, the SL mesh importer has some oddities where collada files which reference the geometry in <polylist> are limited to 21844 triangles per material. If a material exceeds that number, the importer will create an additional material for the remaining triangles above 21844. Hence your medium LOD model, which has less than 21844 tris per material, won't have that secretly created material, hence the numbers don't match anymore.

Blender does create such collada files with <polylist> up to version 2.78. Version 2.79 seems to have a modified collada exporter which does reference the geometry in <triangles> which doesn't have the 21k Tris limit. (According to Drongle McMahon, there will be a similar behavior, but at a much larger vertex count)

So in case you were using a Blender version below 2.79, you could try to export your original meshes with 2.79 and see if that solves the problem.

Having said that, indeed I agree with all of those who recommend to use low poly models in-game. Sculpted models don't belong to any game environment per se. The in-game low poly model is preferably created by retopologizing the high poly mesh, and not by running it through a decimation function actually.

Edited by arton Rotaru
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On 2/26/2018 at 3:41 PM, arton Rotaru said:

Addressing the initial problem of the OP, the SL mesh importer has some oddities where collada files which reference the geometry in <polylist> are limited to 21844 triangles per material. If a material exceeds that number, the importer will create an additional material for the remaining triangles above 21844. Hence your medium LOD model, which has less than 21844 tris per material, won't have that secretly created material, hence the numbers don't match anymore.

Blender does create such collada files with <polylist> up to version 2.78. Version 2.79 seems to have a modified collada exporter which does reference the geometry in <triangles> which doesn't have the 21k Tris limit. (According to Drongle McMahon, there will be a similar behavior, but at a much larger vertex count)

So in case you were using a Blender version below 2.79, you could try to export your original meshes with 2.79 and see if that solves the problem.

Having said that, indeed I agree with all of those who recommend to use low poly models in-game. Sculpted models don't belong to any game environment per se. The in-game low poly model is preferably created by retopologizing the high poly mesh, and not by running it through a decimation function actually.

Thanks Arton!

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