Box3.SetFromObject() does not always return the minimal AABB

[huangyulin]

Is your feature request related to a problem? Please describe.

When I load a model, I find that the rotation of all objects is 0, but the model rotates. At this time, the box selection range displayed by boxhelper is much larger than the actual area of the model. The evidence shows that the actual angle of the model is deflected. If the rotation of the model is modified by the program, I find that the box selection range of boxhelper will be larger. After verification, import the model into 3DMAX, adjust the model angle, reset it with resetxform, and then use boxhelper to box it for normalization. I want to know if threejs has a function like resetxform in 3DMAX

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[Mugen87]

Please write your post in English. It can then be reopened.

[WestLangley]

I assume this will be reopened...

For computational efficiency, the computed AABB may be larger than the minimal AABB.

Here is a similar example.

const geometry = new THREE.PlaneGeometry( 10, 10 );
geometry.rotateX( - Math.PI / 2 );
geometry.rotateZ( - Math.PI / 4 ); // rotate geometry

mesh = new THREE.Mesh( geometry, new THREE.MeshBasicMaterial( { color: 0x0080ff, side: THREE.DoubleSide } ) );
mesh.rotation.set( 0, 0, Math.PI / 4 ); // apply inverse rotation to mesh
scene.add( mesh );

const helper = new THREE.Box3Helper( new THREE.Box3().setFromObject( mesh ), 0xffff00 );
scene.add( helper );

related: #20024

[huangyulin]

After two angle flips, the plane looks horizontal, but the range calculated by box3 is the range after two angles. I want to know how to get the horizontal time range. Do you have a good way

[WestLangley]

@huangyulin #20024 adds support for Box3.setFromObject( object, minimalAABB ) , which should produce the correct answer for your use case.

I want to know if threejs has a function like resetxform in 3DMAX

I am not familiar with 3ds Max. Maybe someone else can answer...

[huangyulin]

@huangyulin #20024 adds support for Box3.setFromObject( object, minimalAABB ) , which should produce the correct answer for your use case.

I want to know if threejs has a function like resetxform in 3DMAX

I am not familiar with 3ds Max. Maybe someone else can answer...

Do you know the difference between expandByObject and setFromObject? I tested them and got the same results

[WestLangley]

Do you know the difference between expandByObject and setFromObject?

three.js/src/math/Box3.js

Lines 112 to 118 in 1a241ef

	setFromObject( object ) {
	this.makeEmpty();
	return this.expandByObject( object );
	}

[huangyulin]

Thank you for your contribution. A parameter has been added to expandbyobject in box3, whether to calculate the minimum boundary range; The problem of my premise is solved perfectly; Thank you for your contributions