# THREE-CSGMesh Conversion of a CSG - (Constructive Solid Geometry) library for use with modern THREE.js Original version: Copyright (c) 2011 Evan Wallace (http://madebyevan.com/), under the MIT license. THREE.js rework by thrax under MIT license. Here's a running demo https://manthrax.github.io/THREE-CSGMesh/demos/CSGDemo.html [](#screenshot) And a shinier, slightly more complex demo: https://manthrax.github.io/THREE-CSGMesh/demos/CSGShinyDemo.html [](#screenshot) And a more complex example showing a text mesh cut into another complex mesh via an intermediate cube: https://manthrax.github.io/THREE-CSGMesh/v2/index.html [](#screenshot) An example showing multiple material groups, and vertex color channel: https://manthrax.github.io/THREE-CSGMesh/demos/CSGStress.html [](#screenshot) CSG is the name of a technique for generating a new geometry as a function of two input geometries. CSG is sometimes referred to as "Boolean" operators in 3d modelling packages. Internally it uses a structure called a BSP (binary space partitioning) tree to carry out these operations. The supported operations are .subtract, .union, and .intersect. By using different combinations of these 3 operations, and changing the order of the input models, you can construct any combination of the input models. In the first screenshot/demo above, I show the possible results with a cube and a sphere... In blue is the result of the .union operation, for sphere->cube and cube->sphere (the result is same in this case ) In green is the result of the .intersect operation, for sphere->cube and cube->sphere (the result is same in this case ) In red is the result of the .subtract operation, for sphere->cube and cube->sphere. Here the result differs based on the order of the inputs. Example usage: # EXAMPLE 0: ```js //Minimal example.. subtract mesh b from mesh a: import {CSG} from "three-csg.js" scene.add(CSG.toMesh(CSG.subtract(CSG.fromMesh(a),CSG.fromMesh(b)),a.material)) ``` # EXAMPLE 1. Verbose... step by step.. ```js // Make 2 box meshes.. let meshA = new THREE.Mesh(new THREE.BoxGeometry(1,1,1)) let meshB = new THREE.Mesh(new THREE.BoxGeometry(1,1,1)) //offset one of the boxes by half its width.. meshB.position.add(new THREE.Vector3( 0.5, 0.5, 0.5) //Make sure the .matrix of each mesh is current meshA.updateMatrix() meshB.updateMatrix() //Create a bsp tree from each of the meshes let bspA = CSG.fromMesh( meshA ) let bspB = CSG.fromMesh( meshB ) // Subtract one bsp from the other via .subtract... other supported modes are .union and .intersect let bspResult = bspA.subtract(bspB) //Get the resulting mesh from the result bsp, and assign meshA.material to the resulting mesh let meshResult = CSG.toMesh( bspResult, meshA.matrix, meshA.material ) ```