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Frustrated with physics.


Sandis Jenkins
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Hello all.

And yet as when I thought I can finally upload my first ever mesh building, i am stuck now with creating physics.

So I have a residential building made in Blender. It has been split in parts to be able to bake textures. Not a super big or complex building. Only around 2.600 triangles. 

I uploaded it to beta SL for testing textures, several times. Every time I just used the auto generated High physics settings, which works pretty well, besides one door that is impossible to walk trough. Once I finalized my built and was finally happy with my textures I started working on the physics. Now I did watch several of the few videos I could find on Youtube about SL physics, and I did read several posts here on the forum, especially when my problem started to occur.

Basically on my first try, my mesh was still split in pieces and when I tried to upload the cube type of physics building, it was not stretching over the whole building. Which from what I can understand was because each piece of mesh needs its own physics model. Okey fine.

Then just for testing purposes I did the Ctrl J in Blender on my whole mesh, and tried to upload it this way. But now whenever I try to apply the physics model, it does not appear in the physics color window in SL uploaded. Even after trying to upload, there is no Prim choice under physics and well it basically did not work. 

So I started trying everything I could think of, and from what I read. I applied all transforms, I tried both merged mesh into one object and as seperated objects, i tried creating new physics models, but for some reason the physics model does not want to apply over the mesh. The auto generator still works, just not the physics model. I even tried to create just a one big cube that is the EXACT size of the whole building(as I read it needs to be the same size) but still, nothing. In the SL uploaded I see the mesh but there are no physics colors over it. So right now Im stuck and not sure what I should do.

I guess I could try uploading every single piece of the mesh and then stich it together, but I really do not want to do that.

 

Any help would be appreciated!

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20 minutes ago, Sandis Jenkins said:

I guess I could try uploading every single piece of the mesh and then stich it together, but I really do not want to do that.

Yes, that's what you want to do. There are a number of reasons why you want to upload something like a complete house as separate parts rather than in one go, the trouble you have with bounding boxes and part sizes is just one of them.

I'd be happy to give you more detailed advice and I'm sure others will too but we need a little bit more details about your buuild first. Do you have any pictures to show us?

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12 hours ago, ChinRey said:

Yes, that's what you want to do. There are a number of reasons why you want to upload something like a complete house as separate parts rather than in one go, the trouble you have with bounding boxes and part sizes is just one of them.

I'd be happy to give you more detailed advice and I'm sure others will too but we need a little bit more details about your buuild first. Do you have any pictures to show us?

Ugh. That was what I feared haha. I don't mind uploading it in parts per say, its just that im worried about stiching it all together in SL such that all parts are positioned in their place perfectly!

Edited by Sandis Jenkins
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I would also recommend to upload it in pieces. This way you also can mix analyzed, and triangle based physics. Triangle based physics are most often cheaper in physics weight than hull physics. You can also avoid the floating 5 cm above the floor effect with tri-based physics. The downside is that the mesh will have to be at least 0.5 meters in each dimension, or doorways will be blocked. There is also the issue with llTargetOmega smooth rotating doors link to a tri-based physics mesh. Calling the function will turn the mesh to the defaulft single convex hull physics, which will block doorways as well, and pushes everybody inside the volume out.

So pieces that are supposed have linked smooth doors, should be analyzed, while meshes you walk on can be tri-based.

Assembling something like this in-world isn't a big deal either.

Edited by arton Rotaru
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Update: So thanks to someone really nice who saw my post and found me in the beta grid I learned a lot and managed to fix my mesh. 

The solution ended up being much better then I though I will end up having to do. Instead of uploading each part of the mesh separately with their corresponding physics file(example wall.dae wall_PHYS.dae, floor.dae floor_PHYS.dae) I learned that I can upload the mesh as a single file while not merging all the pieces together. The trick was that in Blender each mesh piece needed a physics model that is named the same way as the piece but ends with _PHYS. This way you can have everything in the same dae file. Just when you export you only export the mesh pieces in "name".dae and then ONLY the physics model pieces in "name"_PHYS.dae.

Honestly from all the tutorials and posts I saw I never saw anybody mentioning that it is possible to be done in Blender. I assumed that I need to export each piece separately and each physics piece separately(adding _PHYS in the end) which just seemed very tedious.

But all in all my mesh is working and all good. Now just to optimize it :)

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4 hours ago, Sandis Jenkins said:

Honestly from all the tutorials and posts I saw I never saw anybody mentioning that it is possible to be done in Blender.

Honestly, I can't even count the number of times just me mentioning the LOD naming convention to be used to upload linksets on this forums. However, the reason why we did not mentioned it in this case is A) your physics will be all of the same type, all convex hulls, or all triangle based. Can't have mixed pyhsics shape types in a single upload. And B) it's easy enough to re-assemble such a simple build in-world.

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13 minutes ago, arton Rotaru said:

Honestly, I can't even count the number of times just me mentioning the LOD naming convention to be used to upload linksets on this forums. However, the reason why we did not mentioned it in this case is A) your physics will be all of the same type, all convex hulls, or all triangle based. Can't have mixed pyhsics shape types in a single upload. And B) it's easy enough to re-assemble such a simple build in-world.

Not sure if I have seen your comments before about physics or not, but if I did i probably didn't understand enough to get it :D But either way I know now :) I ended up using planes as I was told it is better for buildings and also since it helps with the "floating above ground" issue. Model with physics ended up being 45Li, which for me feels quite good, especially for first time build :) 

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5 minutes ago, Sandis Jenkins said:

I ended up using planes as I was told it is better for buildings and also since it helps with the "floating above ground" issue.

Just keep in mind, if you link something to it that is using a script with the TARGET_OMEGA function, physics will fail. Same when a dimension is less than 0.5 meters. In such cases, analyzing the PHYS will fix that.

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6 minutes ago, arton Rotaru said:

Just keep in mind, if you link something to it that is using a script with the TARGET_OMEGA function, physics will fail. Same when a dimension is less than 0.5 meters. In such cases, analyzing the PHYS will fix that.

Thank you for the tip :)

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