Fluid boundary collision bug?

Questions
1

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As you can see from the diagram, the boundary collision is wrong, why is that? Is the SDF boundary mesh inaccurate with the actual 3D mesh? Is it a bug with the SDF generator or a bug with the fluid renderer?

2

cc @Evgeni_Popov (please be patient, our forum master is on well deserved vacation)

3

Because of Fix obj loader and exporter to support handedness correctly by bghgary Ā· Pull Request #14884 Ā· BabylonJS/Babylon.js Ā· GitHub, there was a breaking change introduced in the way .obj files are loaded, which makes this demo fail.

A simple fix is to set scene.useRightHandedSystem = true:

A more complicated fix would be to change how the SDF generator loads .obj filesā€¦

[EDIT] Iā€™ve updated the doc page:

2 Likes
4

SDF is a pre-computed generated 3D texture, and can the 3D texture be moved and updated in a 3D scene? Can I see how to update the 3D texture calculation?

5

We donā€™t use a 3D texture because we do everything (fluid simulation + SDF calculation) on the GPU (hence why itā€™s slow).

The parsing of SDF data is done in _ParseSDFData (the SDF files are in FluidRendering/src/assets/sdf at main Ā· Popov72/FluidRendering Ā· GitHub), which fills a SDFArray, which is then used in SDMesh to calculate the distance to the mesh.

6

Thanks for the answer, can you take a screenshot and tell me which file the GPU SDF calculation collision detection code is in? I didnā€™t find it

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We donā€™t do anything on the GPU, everything is done on CPU side. The SDF calculation for SDF meshes is done in SDFHelper.SDMesh. The collision handling code is in FluidSimulationDemoBase._checkCollisions.