Need help with the physics of a spiral staircase

[Manes Siamendes]

Ok so I have modeled this spiral staircase shown here:

And the following physics mesh for it:

Both the object and physics mesh each consist of three parts; the stairs, the guardrail, and the center cylinder. However, when I try to load the physics mesh into the uploader, I am getting the following result here:

I do not know what is happening. The guardrail physics look good, but for some reason the stairs are grabbing the center cylinder physics mesh and stretching it to be the size of the stairs and the center cylinder is grabbing the stairs physics mesh and squishing it down to the size of the cylinder. Can anyone please tell me why it's doing this and how to fix this?

[arton Rotaru]

The importer is expecting the following naming convention to match LOD and physics shape with multi object uploads.

Name your objects in your modeling app like this:

Center

Stairs

Rails

and the corresponding physics meshes:

Center_PHYS

Stairs_PHYS

Rails_PHYS

For LOD models the suffix looks like this from Medium to Lowest:

_LOD2, _LOD1, _LOD0

[Chic Aeon]

OR you can link your stairs and link your physics model. Apply location rotation and scale to both as well as origin to geometry.  

OR you can import each separately and put together inworld

Your center pole physics is WAY to dense and should probably be a hexagon.   And in general your other physics model really needs to be simpler also. Cubes (resized of course) or planes that "approximate" your physics. The uploader is NOT happy with dense physics models and if it uploads them the cost can be beyond usable.  So test on the beta grid maybe?   

Edited March 2 by Chic Aeon
spelling

[Manes Siamendes]

38 minutes ago, Chic Aeon said:

OR you can link your stairs and link your physics model. Apply location rotation and scale to both as well as origin to geometry.  

OR you can import each separately and put together inworld

Your center pole physics is WAY to dense and should probably be a hexagon.   And in general your other physics model really needs to be simpler also. Cubes (resized of course) or planes that "approximate" your physics. The uploader is NOT happy with dense physics models and if it uploads them the cost can be beyond usable.  So test on the beta grid maybe?   

Yes I test on the beta grid all the time. And I know the physics model needs to be optimized further. I was just testing on the uploader. Glad you let me know about the proper naming convention, though. 

Edited March 2 by Manes Siamendes

[Manes Siamendes]

@arton Rotaru @Chic Aeon Ok so I am still having trouble here. I optimized the physics mesh so it has less triangles and made the center pole a triangular prism as well.

I also renamed all three physics meshes in Blender to the following:

spiralStairs_PHYS

spiralStairsRail_PHYS

spiralStairsCenter_PHYS

I bundled all three of them in one Collada file, 'spiralstairs_PHYS.dae." The main model is in 'spiralstairs.dae.' But when I tried putting it all in the uploader, I still am getting the same problem. The stairs mesh is still grabbing the center physics mesh and the center pole is still grabbing the stairs physics mesh.

Just what else am I doing wrong? I want to upload the whole thing consisting of three linked meshes each with its own corresponding physics mesh combined into one object. Is that simply not possible?

[arton Rotaru]

2 hours ago, Manes Siamendes said:

Is that simply not possible?

That is possible, I do it all the time.

Just because you didn't mention it explicitly in your post, you also did name the visual meshes corresponding to the *_PHYS names, just without a suffix?

If that is the case, and it still doesn't work, try to avoid similarities in the names. Which in your case is 'spiralStairs'. Try naming it all like I did in the example. Giving each piece a distinct name.

[Aquila Kytori]

3 hours ago, Manes Siamendes said:

also renamed all three physics meshes in Blender to the following:

spiralStairs_PHYS

spiralStairsRail_PHYS

spiralStairsCenter_PHYS

I bundled all three of them in one Collada file, 'spiralstairs_PHYS.dae." The main model is in 'spiralstairs.dae.' But when I tried putting it all in the uploader, I still am getting the same problem. The stairs mesh is still grabbing the center physics mesh and the center pole is still grabbing the stairs physics mesh.

If you also have the 3 high lod models named exactly the same (without suffix) then it sounds like you are doing everything correctly.

Quick test using my own spiral staircase but using your object names:

High Lod objects:

 

Repeat for Physics objects:

 

When Uploading to SL, select the spiralstairs.dae file (containing the 3 high lod objects) then you should find that the spiralstairs_PHYS.dae file has been automatically loaded into the Physics tab for you :

 

Note that in Blender I tried selecting the objects in different orders before exporting and it made no difference. Each time the  physics models were aligned correctly to the visual models.

 

If you are still having problems post a screenshot of the full Blender window and maybe we will spot something. or better still share your Blender file

 

3 hours ago, Manes Siamendes said:

Just what else am I doing wrong? I want to upload the whole thing consisting of three linked meshes each with its own corresponding physics mesh combined into one object. Is that simply not possible?

A link to an earlier post about uploading linksets of LOD and Physics models

 

Edited March 2 by Aquila Kytori

[Aquila Kytori]

3 hours ago, Manes Siamendes said:

I optimized the physics mesh so it has less triangles and made the center pole a triangular prism as well.

When walking up a narrow spiral staircase in SL it is very easy to "walk up over" the outer rail and fall off. To avoid this increase the height of the rail as much as possible in the Physics mesh.

Something like in the gif below, blue is the physics model for the rail object:

Also increasing the height of the physics rails will increase the size of the triangles in the physics model which has the benefit of lowering the physics cost ! 

Link to a thread dealing with a spiral staircase :

 

 

[Chic Aeon]

Just to clarify you do not need to name your physics model in any way if you ONLY HAVE ONE linked model that you are using for the physics.  You DO need to be SURE and apply location, rotation and scale to EACH model (both finished model and the simplified physics model). You need to have origin to geometry set on both.  

It will not work without doing that.  

 

I seldom upload linksets but  when I do use the  _Phys method each section always has location, rotation and scale appled as well as origin to geometry. If I forget (either as a linkset or as a single model) I get something like you are getting

 

Over a decade ago an oldtimer (not aquila  but she was around then ) told me (us) to ALWAYS apply location, rotation and scale, and origin to geometry and that will solve MANY problems.  So keep that in mind. 

 

Hopefully Aquila's always lovely and pretty explanation fixes things for you.  If not here is an OLD video (not the new interface) that might be helpful even though things are in different places now. 

 

I have to say that I haven't watched this in a long while and while there ARE occasions where you really want the physics to be close to the actual model (like with openings for roleplay) most of the time simplicity is much better. Hopefully that thought carries through and the screen capture Youtube chose is misleading LOL.  Anyway I hope you work this out.  

 

I will say that I have had a couple of complex builds over the years that I could not make a one piece physics model that the uploader would understand.  I don't think that is your case though 

 

Edited March 2 by Chic Aeon
adding info

[Manes Siamendes]

@Aquila Kytori

@Chic Aeon

So exactly what size do the physics meshes have to be in relation to the actual meshes? Do they need to fit within the actual meshes, or do they just have to be the size of the actual meshes' bounding boxes? And I did apply location, scale, and rotation.

Edited March 2 by Manes Siamendes

[Chic Aeon]

I will let Aquilla answer that  ---   BUT 'I" always build my physics messes right on top of my actual objects. I usually use cubes -- Aquila likes plains better :D.  So for me they are the same size and "cover" the actual meshes. You can't be sloppy with your physics meshes or you will have issues.  That I can guarantee from experience.   

[Aquila Kytori]

2 hours ago, Manes Siamendes said:

So exactly what size do the physics meshes have to be in relation to the actual meshes? Do they need to fit within the actual meshes, or do they just have to be the size of the actual meshes' bounding boxes?

Yes its the bounding box X Y Z dimensions of the physics model that should match (approximately at least) the bounding box dimensions of the visual model.

If the physics BB is not the same as the visual objects BB it will be stretched or squished to size by the SL mesh uploader.

If necessary you can view the BB of an object in Blender by selecting the object >Object data tab > Viewport Display > Bounds.

 

Is there a particular reason why you have separated the spiral stairs into 3 separate objects the way you have?

Edited March 2 by Aquila Kytori

[Chic Aeon]

Just saw this impressive staircase and thought of this thread