WebGLRenderer frustum culls using bounding sphere, but sorts using object origin?

[stevesan]

three.js/src/renderers/WebGLRenderer.js

Line 1318 in fb46a77

if ( sortObjects ) {

Wouldn't it be more consistent to also sort by bounding-sphere-center? Then transparent objects don't all need to be centered around their origin. And this would be more consistent with other engines.

[stevesan]

To prevent a breaking change, how about adding a flag to THREE.Mesh indicating if it should use bounding-sphere or origin for sorting? boolean THREE.Mesh.sortByBoundingSphere

[WestLangley]

Wouldn't it be more consistent to also sort by bounding-sphere-center?

Also? Can you show a code snippet?

transparent objects don't all need to be centered around their origin.

Can you please elaborate on that?

[mrdoob]

Interesting... We can definitely explore this.

Any chance you can create a jsfiddle? Should be a matter of creating a couple of transparent cubes and applying a translate transform to the geometry.

Wouldn't consider this a breaking change though?

[stevesan]

Sure thing, I'll create a fiddle to demonstrate this.

[stevesan]

Alrighty, here's the fiddle: https://jsfiddle.net/wshtoc9o/29/

[stevesan]

Also? Can you show a code snippet?

Oh yeah. I'm referring to the fact that frustum culling is done by bounding sphere, so we're computing it already:

three.js/src/math/Frustum.js

Line 91 in 35a26f1

if ( geometry.boundingSphere === null )

[mrdoob]

So we mainly have to change these lines to this?

_vector3.copy( object.geometry.boundingSphere.center )
	.applyMatrix4( object.matrixWorld )
	.applyMatrix4( _projScreenMatrix );

[WestLangley]

object.geometry.boundingSphere can be null. For example, if the object is not frustum-culled.