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Hector Roffo

Problem with Mesh physics shape please help!

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Where do I begin. I am creating a house and I cannot seem to understand what I am doing wrong with physics, I looked up many videos and countless forum posts, I tried various methods and still end up with the physics either rotated on its side or just scaled wrong.
 

This is the house

67a516c55a8492e228f1d08a84cf6478.png

 

This is the physics I started to do

d2bb392846a8926896c8ec4265852775.png

 

This is the result I get with just trying to do the front and the roof I can continue creating the shape because I wanted to see if I can get that part correct but I seem to never get the result I need

73036e7640a963adce77816133944c57.png

 

I am about to lose my mind if anybody knows anything please help!!!

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One thing comes to mind.  The physics shape is scaled by the uploader to match the mesh.  So you MUST have vertices in the physics that match the vertices of the extremities of the mesh.

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There are 3 general rules you should be trying to comply with when making a Physics model for your house.

  • 1: Each object should have its own Physics model. For example, if the house  consists of of two separate objects, a roof model and a walls model, then the roof object will have its own physics model and the walls model will have its own physics model.
  • 2: The Bounding box dimensions of the Physics model should match the Bounding box dimensions of the visual (High LOD) model. If the BB dimensions are different then the SL mesh uploader will stretch or squish the Physics model to fit the BB of the visual mesh. This will result in misaligned collision surfaces.
  • 3: Keep the Physics model as simple as possible. In the Physics model only have collision surfaces where they are really needed. For example window opening can be ignored in the Physics model. Keeping it simple also means low physics costs. The SL mesh uploader  likes to find  large tris/quads in the Physics model and will reward you by reducing the Physics cost. If it sees alot of small/thin tris/quads then ......up goes that cost.

When looking at the screenshot of the preview window you posted the first thing I ask is "where are the front walls" ? The roof physics model has been stretched to fit the building. Can you confirm that you are complying with rule N°1?  The physics model you show, is that a single mesh object.

Also; in the preview window the physics model looks more complicated than the physics model you say you are testing. What looks like 3 windows are also outlined in yellow (2 at the front one at the side)?

73036e7640a963adce77816133944c57.thumb.png.a01d586940f6e642724970b3f0a90d62.png

Doing a quick count of the triangles in the physics model (assuming the roof physics model you show is single sided) I make it less than 100 tris, the mesh uploader is indicating a count of 132 ?

The building is it a single mesh object or a collection of objects?

Best is upload one object (along with its physics model) at a time. :)

 

Edited by Aquila Kytori
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On 10/8/2019 at 9:25 PM, Hector Roffo said:

This is the physics I started to do

d2bb392846a8926896c8ec4265852775.png

There is so much wrong with this collision mesh I'm not even sure where to start...

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On 10/8/2019 at 1:17 PM, Hector Roffo said:

I am not using blender but I am doing the equivalent of rotation and scale. 

What are you using? There will probably be someone here familiar with it who can help.

Modeling this isn't that hard. Model the outside walls as a floor plan. Extrude upwards for the wall height. Add a floor to fit. Allow a small gap, about 0.05m, between floor and walls, because the uploader's concave object decomposer is not too bright, and tends to cut up concave forms in strange ways. It does better if you use simple convex geometric forms.  Add a ceiling to fit. Same rules. Make a big solid object with a triangular cross section for half the roof. Make two more, cut to almost but not quite touch the first, for the cross-roof. You can't use the attic, but probably didn't plan to anyway.

Edited by animats

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On 10/10/2019 at 1:33 AM, Kyrah Abattoir said:

There is so much wrong with this collision mesh I'm not even sure where to start...

This reply to someone asking for help has to be:

1:The winner of the prize for the  most useless answer of the week.

2: Simply not true. (see images below)

 

On 10/10/2019 at 5:19 AM, animats said:

 

........ Allow a small gap, about 0.05m, between floor and walls, because the uploader's concave object decomposer is not too bright, and tends to cut up concave forms in strange ways. It does better if you use simple convex geometric forms.  Add a ceiling to fit. Same rules. Make a big solid object with a triangular cross section for half the roof. Make two more, cut to almost but not quite touch the first, for the cross-roof. You can't use the attic, but probably didn't plan to anyway.

From the screenshot of Physics menu in the SL mesh up-loader we can see that Hector is correctly not Analyzing the physics model so this dose not apply in this case.

 

1-min.thumb.png.a7b00e25cee65b3354b0473cd5ffb4d9.png

 

2-min.thumb.png.837781ec818868f4ea3edb8f8565b3b6.png

 

4-min.thumb.png.b6fce5deecc9aea13109d4023821d16b.png

 

3-min.thumb.png.d65eda71cd260ad56e9d19cef39ca5c7.png

 

5.thumb.png.92587736ae23358f82dcba8dc7d0e8fe.png

 

6.thumb.png.b313a4216c28e3b78c722b8c2a98f83f.png

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15 hours ago, Aquila Kytori said:

This reply to someone asking for help has to be:

1:The winner of the prize for the  most useless answer of the week.

2: Simply not true. (see images below)

I'll just ignore that part.

15 hours ago, Aquila Kytori said:

 

2-min.thumb.png.837781ec818868f4ea3edb8f8565b3b6.png

Very good example there: Clean geometry with no loose edge.

Edited by Kyrah Abattoir

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2 hours ago, Aquila Kytori said:

apart from a few extra tris in the roof the 2 collision meshes are almost the identical !

I would probably have kept the extra tris in the roof physics, at least the ones on the lwoer slopes. A roof is a walkable surface and they shouldn't add anything to the land impact.

I've stayed away from this thread until now because Aquila explained it so well but since I ended up posting here anyway: @Hector Roffo, it seems to me the problem is that you tried to do too much in one go and got confused (and apparently so did everybody else looking at your model). Two obvious clues here are the physics model you started with that combines roof physics requiring unanalyzed and wall physics requiring analyzed physics an a single mesh and the windows showing up with their own over complicated physics in the upload window screenshot.

When you make something as complex as a mesh house, think in modules. The roof is a separate mesh, the walls are a separate mesh (or as often as not several separate meshes), the windows are a separate mesh (and you only make and upload one of them and duplicate it in-world) etc. I would also strongly advice you against uploading coalesced meshes, there are so many things that can go wrong when you try to do that. Focus on one part at a time, upload each part separately and assemble in-world.

 

Edited by ChinRey

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22 hours ago, ChinRey said:

I would probably have kept the extra tris in the roof physics, at least the ones on the lwoer slopes. A roof is a walkable surface and they shouldn't add anything to the land impact.

I agree about walkable roofs but ............. well I can't help thinking the  Lag Fighter  is going a bit soft😮

More accurate roof collision surfaces :

7.thumb.PNG.70f5b97952f2d3ed2bd88a018c3abfa8.PNG

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10 hours ago, Aquila Kytori said:

well I can't help thinking the  Lag Fighter  is going a bit soft😮

Don't skimp on the essentials! ;)

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Seems like the roof of the physics isn't attached (Not sure what it called in blender, in 3ds max its called "attach") with the wall of the physics. So the physics uploader take only the roof to stretch for the entire house. Try to make both roof and the wall as one object by "attach".

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3 hours ago, MeshPromo said:

Try to make both roof and the wall as one object by "attach".

Good point, except it should be the other way round: Make roof and walls as two separate objects both in the visuals and physics. There are cases where it makes sense to make roof and walls as a single mesh but this is clearly not one of them.

 

 

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