Threecsg flat sides when expecting volumetric result

问题

The issue:

Subtracting a cube from a sphere provides a result where the z axis retains volume, but the y and x axis produce flat disks, as show in the image. I am not sure why the sphere is losing volume on those sides. I am using a typical subtract with threeCSG.

Code:

  var geometry = new THREE.CubeGeometry( 100, 100, 100 );
  var material = new THREE.MeshLambertMaterial( {color: 0xff0000, side: THREE.DoubleSide, transparent:true, opacity: .5} );
  var cutter = new THREE.Mesh( geometry, material );

  var geometry2 = new THREE.SphereGeometry(60,32, 32);
  var material2 = new THREE.MeshLambertMaterial( {color: 0x00ff00, side: THREE.DoubleSide, transparent:true, opacity: .5} );
  var massing = new THREE.Mesh( geometry2, material2 );


  var cutter_bsp = new ThreeBSP(cutter);
  var massing_bsp = new ThreeBSP(massing);

  var new_bsp = massing_bsp.subtract(cutter_bsp);

  var result = new_bsp.toMesh(material2);
  result.geometry.computeVertexNormals();
  result.position.y = 200;

I am using v 103, but the issue seems to be irrelevant to version as 77 shows the same issue.

Question: Why are the result's sides flat? Do I need to convert the geometry in some way before the subtract operation?

Here is the result above the box and sphere:

回答1:

@manthrax posted his code here as an answer but then deleted it. It is available here: https://github.com/manthrax/THREE-CSGMesh

Forked at https://github.com/radio412/THREE-CSGMesh/ with export token removed.

Meshes need updateMatrix() called before the operation if any transformations are applied.

This code works well. I do not know why the legacy ThreeCSG code was not working however, and it would be good to have some insight.

来源：https://stackoverflow.com/questions/55499314/threecsg-flat-sides-when-expecting-volumetric-result

标签

javascript

three.js

threecsg