Meshes as collider scene/demo

https://vimeo.com/235828843

Hi all,
Inside of Eddy you can extract a distance field, and a velocity field, from imported 3D assets.
Here is an example of using an animated input alembic mesh cache as a collider in Eddy.

https://www.dropbox.com/s/rl5ro4aerofml1e/meshColliders.zip?dl=1

Things to note with colliders:

  • E_MeshtoVolume node, the Voxel Resolution should be kept as low as possible on your meshes, as it affects speed of simulation a fair bit.
  • Consider creating lower poly collision wrap meshes inside your 3D application, this can help avoid issues with complex meshes and may help speed also.
  • When viewing the distance channel from an input mesh in the OPENGL viewport, goto the vizualizer tab and select 'Force SDF" This will show you the Signed Distance Field created from the mesh, the default iso/gas display is not very useful here.
  • Always make sure you have Max Time Steps turned up to at least about 3 in the Element node.

2 Likes

Hi Matt,

are there any tricks for concave surfaces? I got a simple mesh but it has a concave top and I want some dry ice to bubble in that cavity and flow down the sides.
I have cranked up the voxel res on the mesh but that shows me that it will have to be insanely high for the sim to get close enough to the mesh:
eddy2

Any clever tricks for this sort of thing?
I can send you the mesh if you like.

Cheers,
frank

Hi frank,
I think you are experiencing a quirk of the mesh system i ran into recently.

  • If the mesh is watertight/sealed, the mesh to volume creates a SDF with the same surface as your input mesh.
    image
  • If it is an open mesh ( or a sealed mesh with anything it considers a mesh error) it will puff out the SDF enabling a ‘shell’. This is so you can work with cards or single sided meshes. When you have a mesh like this you can adjust the “Shell width” to adjust how much it puffs the shell out (in the prior example shell width does nothing )
    image

Happy to have a look at the mesh if you still need, send in any common format.

cool, will email the mesh since the forum doesn’t accept zip files.

Heya frank, it was a small error on the mesh, forcing it into “shell mode”
image

I fixed the mesh for you and got a result like this on the sdf.

image

Here’s the adjusted mesh to save you a little time. https://www.dropbox.com/s/6bvqtfv02lgizt9/Volcanoe2_fix.abc?dl=1

I got an ok SDF before with the nGon as well. My issue is the distance
between the gas and the surface. Yuo can see in my screen shot how the
gas doesn’t collide with the surface but well above it.
Is the the only way around this is to increase the voxel resolution?

Oh ok, sorry the shell stuff is just a common issue I get.
It may be an issue of needing higher res , I’ll have another look today.

@frank

I’ve made a scene out of your volcano you can use for reference. I’m not sure what was happening with your collider in your example, mine is at 256 voxel res and working fairly fast on the 1080ti.
I made the scene fairly large to more match a volcano opening of 10m or so. So its more like pyroclastic dense cloud than dry ice sorry, but it should still help for reference.
The collision seems good for me, see what you think.

https://www.dropbox.com/s/kfj03ohpaeptnmu/volc.nk?dl=1

Cheers mate

image

Thanks Matt. Interesting that my collision was way off and your sits just fine.
I will have to have another look what went wrong.
Thanks!