CODEWITHSUNDEEP
javascriptobjectthree.js3d
derseitzer
derseitzer

Reputation: 159

three.js box3 of a imported sphere

i have a short question: I know how to calculate the boxes of my (imported) 3dobjects f.e.

var box = new THREE.Box3().setFromObject(obj);

With this i can compute boxes for my objects and i can merge them together if i want.

The problem is, now i have these 2 objects https://i.sstatic.net/dcjw2.jpg

The solution seems quite simple: i need to compute the left and right spherebox and put them together, but both of these 2 objects are imported with stlloader. I'm not sure how stlloader exactly works, (it seems for me like its all 1 huge mesh) so i'm not even sure if this is possible.

so my questions: 1. how can i compute a box with the shape of a sphere of my sphere object. 2. Is this even possible for my stl object? (I will try when i get the answer for question 1)

Edit: Question 1 should somehow be working with .computeBoundingSphere.. is there a way to make this visible?

Upvotes: 1

Views: 667

Answers (1)

Mugen87
Mugen87

Reputation: 31076

  1. how can i compute a box with the shape of a sphere of my sphere object.

Well, in three.js you have the choice between two bounding volumes. THREE.Box3 represents an axis-aligned bounding box (AABB) whereas THREE.Sphere represents a bounding sphere. If you need a box with the shape of a sphere, use THREE.Sphere.

  1. Is this even possible for my stl object?

The method setFromObject() does only exist for THREE.Box3. However, you can compute the bounding sphere via THREE.BufferGeometry.computeBoundingSphere(). This sphere is defined in local space, however. You can use THREE.Sphere.applyMatrix4() to transform it into world space by passing in the world matrix of the 3D object.

is there a way to make this visible?

There is no helper class for bounding spheres. But you can easily create a helper mesh based on THREE.SphereBufferGeometry. Something like:

const geometry = new THREE.SphereBufferGeometry( boundingSphere.radius );
const material = new THREE.MeshBasicMaterial( { color: 0xff0000, wireframe: true } );

const mesh = new THREE.Mesh( geometry, material );
mesh.position.copy( boundingSphere.center );
scene.add( mesh );

three.js R109

Upvotes: 1

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