MeshExploder causes submeshes to rotate

Questions
1

Hello.
I have a parent/child mesh structure. The parent rotates around the Y axis and the submeshes rotates fine with it. If I add an MeshExploder to the mix, the submeshes “inherits” the rotation and starts rotate around their own Y-axes. Sample here: https://playground.babylonjs.com/#Q78ZB6#1
Is this by design or a bug?
All the best,
—bjorn

2

Pinging @danjpar who created the MeshExploder !

3

@bjornbacklund
The children rotate because their parent rotates. I’ll dig around to see if there is a way to ignore the inherited animations.

A quick workaround is to create an empty mesh and set that as the parent for the smaller cubes.
https://playground.babylonjs.com/#Q78ZB6#2

1 Like
4

Thanks but that does not solve the problem. The small cubes should still circle around the center cube while “exploding in/out”.

5

Sorry

https://playground.babylonjs.com/#Q78ZB6#3
After messing around in the code, I realize the smaller cubes should be following the large cube like the sphere is.

@Deltakosh
Here is the code that is setting the positions of the exploding meshes. I imagine an easy fix would be to have a boolean flag on the explode function to update the origin vectors with the centermesh/parent transformations.

public explode(direction: number = 1.0): void {
    for (var index = 0; index < this._meshes.length; index++) {
        if (this._meshes[index] && this._meshesOrigins[index] && this._toCenterVectors[index]) {
            this._toCenterVectors[index].scaleToRef(direction, this._scaledDirection);
            this._meshesOrigins[index].addToRef(this._scaledDirection, this._newPosition);
            this._meshes[index].setAbsolutePosition(this._newPosition);
        }
    }
    this._centerMesh.setAbsolutePosition(this._centerPosition);
}

Any recommendations for easiest way to update those vectors?

6

BTW, any plans to make the MeshExploder an Animatable ?
—bjorn
#bjornsplayground

7

My guts tell me that if we want to support parent hierarchy we should simply call .position instead of setAbsolutePosition

Thoughts?

8

I’ll keep messing around with the code. Right off the bat, changing to this._meshes[index].position = this._newPosition; allows for the parent transformations, however, only one of the smaller cubes are present (or all of the smaller cubes in one position).

9

I think the latter. Can you somehow recreates your tests in the PG?

10

https://brave-gates-959b79.netlify.app/

11

I’ll rewrite the code as a function in the playground

1 Like
12

Any progress on this?
Would love to see a fix, here is a sample using the exploder (would be awesome to be able to rotate the cube)… https://youtu.be/tPfEhi6SOIY
#bjornsplayground