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three.jsrenderingedges

How to render edges as cylinders?


I've loaded an OBJ polyhedron and I've used EdgesGeometry() to extract its edges:

var edges = new THREE.LineSegments(new THREE.EdgesGeometry(child.geometry), new THREE.LineBasicMaterial( {color: 0x000000}) );

But I would like to render each edge as a cylinder with configurable radius. Something like this:

Dodecahedron with edges rendered as cylinders.


Solution

  • Teasing picture ;)

    A customizable solutuion, which you can start from:

    var edgesGeom = new THREE.EdgesGeometry(dodecahedronGeom); //EdgesGeometry is a BufferGeometry
    
    var thickness = 0.25; // radius of a cylinder
    
    for (var i = 0; i < edgesGeom.attributes.position.count - 1; i+=2){
    
      // when you know that it's BufferGeometry, you can find vertices in this way
      var startPoint = new THREE.Vector3(
        edgesGeom.attributes.position.array[i * 3 + 0],
        edgesGeom.attributes.position.array[i * 3 + 1],
        edgesGeom.attributes.position.array[i * 3 + 2]
      );
        var endPoint = new THREE.Vector3(
        edgesGeom.attributes.position.array[i * 3 + 3],
        edgesGeom.attributes.position.array[i * 3 + 4],
        edgesGeom.attributes.position.array[i * 3 + 5]
      );
    
      var cylLength = new THREE.Vector3().subVectors(endPoint, startPoint).length(); // find the length of a cylinder
      var cylGeom = new THREE.CylinderBufferGeometry(thickness, thickness, cylLength, 16);
      cylGeom.translate(0, cylLength / 2, 0);
      cylGeom.rotateX(Math.PI / 2);
      var cyl = new THREE.Mesh(cylGeom, new THREE.MeshLambertMaterial({color: "blue"}));
      cyl.position.copy(startPoint);
      cyl.lookAt(endPoint);  // and do the trick with orienation
      scene.add(cyl);
    }
    

    jsfiddle example