Physics issue: Merged and rotated mesh goes through the floor

[splash27]

The problem is here: https://www.babylonjs-playground.com/#RAYW6X

My mesh partially goes through the floor while the physicsImpostor is applied. Can I correct it's behavior on my mesh?

[JohnK]

A search for "through floor" in the forum seems it is a common problem with physics engine. Happens when you object is too small. Need to scale up the object. Just how small you need to go you will have to experiment with https://www.babylonjs-playground.com/#RAYW6X#1

[Raggar]

In this case, it looks like the merging of the meshes messes with the impostor system. It creates a single shape with the following halfExtents:

x: 0.1

y: 0.30000000596046444

z: 0.5000000029802323

 

And this does not quite match the L-shape you are trying to achieve. What you want to do instead, is create a compound-shape by using the parent-child system in BJS:

https://www.babylonjs-playground.com/#RAYW6X#2

 

[splash27]

@Raggar, great!

However parenting system is not comfortable in cases of spawning instances. You'll have to create instance for every child and attach impostor for every child.

Can I fix halfExtents manually after merging meshes? If yes, how I can do this? I can't find such property in Impostor's properties.

[Raggar]

In that case, the pistol will only be represented by a box, and not a compound shape like an L.

[splash27]

If dropped pistol will act like a box in Physics world this is not a big problem in my simulation.

It should looks like compound shape however the box-like colliding is a compromise that I can accept.

How to do this?

[splash27]

My solution: https://www.babylonjs-playground.com/#RAYW6X#3

It's a little bit similar with solution by @Raggar, however less expensive and more universal (I think). Yeah, the main disadvantage is simplifying physics till bounding box, but it can be accepted in my case.

Anyway, it still looks like a hack. I wonder if merging algorithm can be fixed inside Babylon's core.