shape='box' Add rigid body, why my rigid body is bigger than the actual object, I don't know what's wrong.

[volcanoqq]

Discussed in #364

^{Originally posted by volcanoqq September 26, 2023}

And then I manually pass in width,height,depth, and it works.

I rotated the object in three.js before adding the rigid body, and then added the rigid body in the physical world in a box way, the rigid body did not apply the rotation, I don't know what went wrong

[yandeu]

If it can't detect the shape, it will add 1x1x1 box.
Or you could try to pass shape while creating the physics.

this.physics.add.existing(object, { shape: "mesh" })

But manually adding a box shape (like you did) is way better for performance.

[yandeu]

Yes, adding a box shape manually, does not take into account the rotation of the object. It just wraps a box as it is.

[yandeu]

Try to just manually switch width and height for now.

[yandeu]

Can you please upload the model?

[volcanoqq]

cell.zip

There are two models, one with the center point in the center and one with the center point not on the object.

There is another problem if the center point is not the center point of the object, the resulting physical rigid body is at the center point instead of the center point of the object

[volcanoqq]

Figure 1 shows the model directly creating the physical body

Figure 2 shows the physical body created after rotating the test1 model

  const test1 = editor.scene.getObjectByName("test1");
  const test2 = editor.scene.getObjectByName("test2");

  // test1.rotateX(Math.PI / 2);
  
  physicsManager.createRigidBodyByObject(test1, {
    shape: "box",
    width: new THREE.Box3()
      .setFromObject(test1)
      .getSize(new THREE.Vector3()).x,
    height: new THREE.Box3()
      .setFromObject(test1)
      .getSize(new THREE.Vector3()).y,
    depth: new THREE.Box3()
      .setFromObject(test1)
      .getSize(new THREE.Vector3()).z,
  });

  physicsManager.createRigidBodyByObject(test2, {
    shape: "box",
    width: new THREE.Box3()
      .setFromObject(test2)
      .getSize(new THREE.Vector3()).x,
    height: new THREE.Box3()
      .setFromObject(test2)
      .getSize(new THREE.Vector3()).y,
    depth: new THREE.Box3()
      .setFromObject(test2)
      .getSize(new THREE.Vector3()).z,
  });

[yandeu]

This works for me:

import { PhysicsLoader, Project, Scene3D, THREE } from 'enable3d'

class MainScene extends Scene3D {
  async preload() {
    this.load.preload('obj1', '/assets/obj1.glb')
  }

  async create() {
    this.warpSpeed()
    this.camera.position.set(2, 2, 4)
    this.physics.debug?.enable()

    {
      const obj1 = (await this.load.gltf('obj1')).scene

      const box = new THREE.Box3()
      const size = new THREE.Vector3()
      const center = new THREE.Vector3()
      box.setFromObject(obj1).getSize(size)
      box.setFromObject(obj1).getCenter(center)

      obj1.traverse(child => {
        if (child.isMesh) {
          child.material.metalness = 0
          child.geometry.translate(-center.x, -center.y, -center.z)
        }
      })

      this.add.existing(obj1)
      this.physics.add.existing(obj1, {
        shape: 'box',
        width: size.x,
        height: size.y,
        depth: size.z
      })
    }
  }
}

PhysicsLoader('/lib', () => new Project({ scenes: [MainScene] }))

[volcanoqq]

It doesn't work for me. Is the model you're testing mine?

If obj1.position.set(0,1,0) then geometry.translate() will it work?

[yandeu]

Yes, your model.

Yes. I tried it with setting a position and it worked. Just do it after the obj1.traverse but before you add.physics.

[volcanoqq]

Okay、I tried using class MainScene extends Scene3D, rotation and center point in my demo and it worked.
But I'm not using the recommended class MainScene extends Scene3D. I'm using import {AmmoPhysics} from "@enable3d/ammo-physics";

I put the demo in https://github.com/volcanoqq/enable3d-app, can you help me take a look at what's the problem cause。

[deepugupta1846]

I am using the 'box' physics collision with the custom width, height and depth but the bounding box is way bigger than the object see image 2
while when i apply 'mesh' it work fine but it will take system performance. Is there any solution for this problem please help!!

[yandeu]

I am using the 'box' physics collision with the custom width, height and depth but the bounding box is way bigger than the object see image 2 while when i apply 'mesh' it work fine but it will take system performance. Is there any solution for this problem please help!!

Not sure. But you can manually adjust it. (See above)

[deepugupta1846]

I want to make generic code with the performance because I am running this solution on mobile. Mesh is solving the problem right now but it is not the optimized way to achieve for this reason I am using 'Box' collider can you please help me how the manual width, height, depth solve my issue

getBoundingSize: function(object){
const self = this;

	let box = new THREE.Box3();
            box.setFromObject(object);

    let size = new THREE.Vector3();
        box.getSize(size);

    let center = new THREE.Vector3();
        box.getCenter(center);

    return size;

}