BufferGeometry: how to render groups of faces

Question

I have 2 geometries and 2 meshes. Main goal is sometimes exclude part of first geometry (so I need 2 groups for that) and show in this time part of 2nd geometry (always 1 g

Answer 1

BufferGeometry.groups is now used to support MultiMaterial ( formerly MeshFaceMaterial ).

geometry.clearGroups();
geometry.addGroup( start1, count1, 0 ); // materialIndex 0
geometry.addGroup( start2, count2, 1 ); // materialIndex 1

var material = new THREE.MultiMaterial( materialsArray );
var mesh = new THREE.Mesh( geometry, material );

If you have a single material and want to render sub-groups of faces, you can use a pattern like so:

geometry.clearGroups();
geometry.addGroup( start1, count1, 0 ); // zero
geometry.addGroup( start2, count2, 0 ); // zero

var materialsArray = [ material ];
var material = new THREE.MultiMaterial( materialsArray );
var mesh = new THREE.Mesh( geometry, material );

geometry.drawRange is ignored when the material is MultiMaterial.

three.js r.72