Question

I’m having difficulties constructing a hollow cylinder in Three.js.

Should I go and construct it using CSG or by stitching the vertices together?

Answer 1

This solution uses ChandlerPrall’s ThreeCSG.js project: http://github.com/chandlerprall/ThreeCSG

(For now, I recommend using the experimental version that supports materials – the uv branch – http://github.com/chandlerprall/ThreeCSG/tree/uvs)

Here’s the code you will need:

// Cylinder constructor parameters:  
// radiusAtTop, radiusAtBottom, height, segmentsAroundRadius, segmentsAlongHeight

var smallCylinderGeom = new THREE.CylinderGeometry( 30, 30, 80, 20, 4 );
var largeCylinderGeom = new THREE.CylinderGeometry( 40, 40, 80, 20, 4 );

var smallCylinderBSP = new ThreeBSP(smallCylinderGeom);
var largeCylinderBSP = new ThreeBSP(largeCylinderGeom);
var intersectionBSP = largeCylinderBSP.subtract(smallCylinderBSP);      

var redMaterial = new THREE.MeshLambertMaterial( { color: 0xff0000 } );
var hollowCylinder = intersectionBSP.toMesh( redMaterial );
scene.add( hollowCylinder );