Detection of collisions using bounding sphere method

Question

Detection of collisions using bounding sphere method

In Three.js, each mesh (THREE.Object3D) comes with useful properties like boundingSphere and boundingBox, along with methods such as intersectsSphere and isIntersectionBox.

I initially thought I could use these for simple collision detection. However, I noticed that collisions were always detected because the boundingSphere's center was consistently at (0, 0, 0). To properly check collisions between two meshes, I realized that I needed to clone the boundingSphere object for each mesh, get its world coordinates, and then utilize intersectsSphere.

This approach might look something like this:

var bs = component.object.geometry.boundingSphere.clone();
bs.center.setFromMatrixPosition(component.object.matrixWorld);
...
if (_bs.intersectsSphere(bs)){

Is this the correct way to handle collision detection using boundingBox/boundingSphere, or is there a more straightforward method available?

javascript three.js collision-detection bounding-volume

Answer 1

Answer №1

To implement collision detection using bounding boxes, it is important to have the boxes in the world coordinate system rather than the local coordinate system of the object. One approach is to clone the volumes and position them correctly in the world coordinates.

Alternatively, you can create new boxes from your meshes for collision detection. For example, if you have a THREE.Mesh named mesh, you can do:

sphere = new THREE.Sphere.setFromPoints( mesh.vertices );

box = new THREE.Box3.setFromObject( mesh );

During development, it can be helpful to visualize the bounding boxes in your scene. You can achieve this using the THREE.BoundingBoxHelper:

var helper = new THREE.BoundingBoxHelper( mesh );
scene.add( helper );

Answer 2

To implement collision detection using bounding boxes, it is important to have the boxes in the world coordinate system rather than the local coordinate system of the object. One approach is to clone the volumes and position them correctly in the world coordinates.

Alternatively, you can create new boxes from your meshes for collision detection. For example, if you have a THREE.Mesh named mesh, you can do:

sphere = new THREE.Sphere.setFromPoints( mesh.vertices );

box = new THREE.Box3.setFromObject( mesh );

During development, it can be helpful to visualize the bounding boxes in your scene. You can achieve this using the THREE.BoundingBoxHelper:

var helper = new THREE.BoundingBoxHelper( mesh );
scene.add( helper );

Detection of collisions using bounding sphere method

Answer №1

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