Unexpected Result Using Threecsg

October 26, 2023 Post a Comment

I'm experimenting with the ThreeCSG library and am attempting to swap out the sphere or normal geometry for a custom made Shape, in this case the heart shape from the 3js examples.

Solution 1:

ThreeCSG cannot subtract a concave mesh correctly. But there is a workaround, since both halves of a heart or convex.

You can subtract the right half of the heart from a cuboid:

functiongetHeartShapeRight() {
    var x = 5, y = 10;
    var heartShape = newTHREE.Shape();
    heartShape.moveTo(x - 5, y - 5);
    heartShape.bezierCurveTo(x - 5, y - 5, x - 4, y, x, y);
    heartShape.bezierCurveTo(x + 6, y, x + 6, y - 7, x + 6, y - 7);
    heartShape.bezierCurveTo(x + 6, y - 11, x + 3, y - 15.4, x - 5, y - 19);
    return heartShape;
}

// right cuboidvar cubeGeoR = newTHREE.CubeGeometry(125, 250, 250);
var cubeMeshR = newTHREE.Mesh(cubeGeoR);
cubeMeshR.position.x += 62.5;
var cubeBSPR = newThreeBSP(cubeMeshR);

// right part of the heartvar heartShapeR = getHeartShapeRight();
var heartGeoR = getHeartGeometry(heartShapeR);
var meshToCutR = newTHREE.Mesh( heartGeoR );
meshToCutR.scale.set(10,10,10);
meshToCutR.position.z -= 80;

// right subtractvar meshToCutBspR = newThreeBSP(meshToCutR);
var resultBspR = cubeBSPR.subtract(meshToCutBspR);
var resultMeshR = resultBspR.toMesh(newTHREE.MeshLambertMaterial({flatShading: true}));

And you can subtract the left half of the heart from a cuboid:

functiongetHeartShapeLeft() {
    var x = 5, y = 10;
    var heartShape = newTHREE.Shape();
    heartShape.moveTo(x - 5, y - 19);
    heartShape.bezierCurveTo(x - 12, y - 15.4, x - 16, y - 11, x - 16, y - 7);
    heartShape.bezierCurveTo(x - 16, y - 7, x - 16, y, x - 10, y);
    heartShape.bezierCurveTo(x - 7, y, x - 5, y - 5, x - 5, y - 5);
    return heartShape;
}

// left cuboidvar cubeGeoL = newTHREE.CubeGeometry(125, 250, 250);
var cubeMeshL = newTHREE.Mesh(cubeGeoL);
cubeMeshL.position.x -= 62.5;
var cubeBSPL = newThreeBSP(cubeMeshL);

// left part of the heartvar heartShapeL = getHeartShapeLeft();
var heartGeoL = getHeartGeometry(heartShapeL);
var meshToCutL = newTHREE.Mesh( heartGeoL );
meshToCutL.scale.set(10,10,10);
meshToCutL.position.z -= 80;
var meshToCutBspL = newThreeBSP(meshToCutL);

// left subtractvar meshToCutBspL = newThreeBSP(meshToCutL);
var resultBspL = cubeBSPL.subtract(meshToCutBspL);
var resultMeshL = resultBspL.toMesh(newTHREE.MeshLambertMaterial({flatShading: true}));

Finally you can create a union of both halves:

// union of left an right halfvar unionBsp = resultBspL.union(resultBspR);
var unionMesh = unionBsp.toMesh(newTHREE.MeshLambertMaterial({flatShading: true}));
scene.add(unionMesh);

See the code snippet:

(functiononLoad() {
  var container, camera, scene, renderer;
  var grey = 0xD3D3D3;
  
  init();
  animate();

  functioninit() {
    container = document.getElementById('container');
    initScene();
    addGridHelper();
    addCamera();
    addLighting()
    addRenderer();
    addOrbitControls();

        // Creates a CSG cut on the cube based on the passed meshcreateCSGDiecutHandle();
  }

  functioncreateCSGDiecutHandle() {

    // left cuboidvar cubeGeoL = newTHREE.CubeGeometry(125, 250, 250);
    var cubeMeshL = newTHREE.Mesh(cubeGeoL);
    cubeMeshL.position.x -= 62.5;
    var cubeBSPL = newThreeBSP(cubeMeshL);
   
    // left part of the heartvar heartShapeL = getHeartShapeLeft();
    var heartGeoL = getHeartGeometry(heartShapeL);
    var meshToCutL = newTHREE.Mesh( heartGeoL );
    meshToCutL.scale.set(10,10,10);
    meshToCutL.position.z -= 80;
    var meshToCutBspL = newThreeBSP(meshToCutL);

    // left subtractvar meshToCutBspL = newThreeBSP(meshToCutL);
    var resultBspL = cubeBSPL.subtract(meshToCutBspL);
    var resultMeshL = resultBspL.toMesh(newTHREE.MeshLambertMaterial({flatShading: true}));

    // right cuboidvar cubeGeoR = newTHREE.CubeGeometry(125, 250, 250);
    var cubeMeshR = newTHREE.Mesh(cubeGeoR);
    cubeMeshR.position.x += 62.5;
    var cubeBSPR = newThreeBSP(cubeMeshR);

    // right part of the heartvar heartShapeR = getHeartShapeRight();
    var heartGeoR = getHeartGeometry(heartShapeR);
    var meshToCutR = newTHREE.Mesh( heartGeoR );
    meshToCutR.scale.set(10,10,10);
    meshToCutR.position.z -= 80;
    
    // right subtractvar meshToCutBspR = newThreeBSP(meshToCutR);
    var resultBspR = cubeBSPR.subtract(meshToCutBspR);
    var resultMeshR = resultBspR.toMesh(newTHREE.MeshLambertMaterial({flatShading: true}));
    
    // union of left an right halfvar unionBsp = resultBspL.union(resultBspR);
    var unionMesh = unionBsp.toMesh(newTHREE.MeshLambertMaterial({flatShading: true}));
     scene.add(unionMesh);
  }

  functiongetHeartShapeRight() {
    var x = 5, y = 10;
    var heartShape = newTHREE.Shape();
    heartShape.moveTo(x - 5, y - 5);
    heartShape.bezierCurveTo(x - 5, y - 5, x - 4, y, x, y);
    heartShape.bezierCurveTo(x + 6, y, x + 6, y - 7, x + 6, y - 7);
    heartShape.bezierCurveTo(x + 6, y - 11, x + 3, y - 15.4, x - 5, y - 19);
    return heartShape;
  }

  functiongetHeartShapeLeft() {
    var x = 5, y = 10;
    var heartShape = newTHREE.Shape();
    heartShape.moveTo(x - 5, y - 19);
    heartShape.bezierCurveTo(x - 12, y - 15.4, x - 16, y - 11, x - 16, y - 7);
    heartShape.bezierCurveTo(x - 16, y - 7, x - 16, y, x - 10, y);
    heartShape.bezierCurveTo(x - 7, y, x - 5, y - 5, x - 5, y - 5);
    return heartShape;
  }

  functiongetHeartGeometry(heartShape) {
    var extrudeSettings = {
      steps: 2,
      amount: 16,
      bevelEnabled: true,
      bevelThickness: 5,
      bevelSize: 1,
      bevelSegments: 1
    };
        returnnewTHREE.ExtrudeBufferGeometry( heartShape, extrudeSettings );
  }

  /**** Helper functions ****/functioncomputeBoundingBox(mesh) {
    var box = newTHREE.Box3().setFromObject(mesh);
    var size = box.getSize();

    return {
      width: size.x,
      height: size.y,
      size: size
    }
  }

  /**** Basic Scene Setup ****/functioninitScene() {
    scene = newTHREE.Scene();
    scene.background = newTHREE.Color(0xffffff);
  }

  functionaddCamera() {
    camera = newTHREE.PerspectiveCamera(70, window.innerWidth / window.innerHeight, 1, 10000);
    camera.position.set(349.11334070460066, 405.44010726325604, 359.3111192889029);
    scene.add(camera);
  }

  functionaddGridHelper() {
    var planeGeometry = newTHREE.PlaneGeometry(2000, 2000);
    planeGeometry.rotateX(-Math.PI / 2);

    var planeMaterial = newTHREE.ShadowMaterial({
      opacity: 0.2
    });
    var plane = newTHREE.Mesh(planeGeometry, planeMaterial);
    plane.position.y = -200;
    plane.receiveShadow = true;
    scene.add(plane);

    var helper = newTHREE.GridHelper(2000, 100);
    helper.material.opacity = 0.25;
    helper.material.transparent = true;
    scene.add(helper);

    var axis = newTHREE.AxesHelper(1000);
    scene.add(axis);
  }

  functionaddLighting() {
    addHemisphereLight();
  }

  functionaddSpotLighting() {
    var light = newTHREE.SpotLight(0xffffff, 1.5);
    light.position.set(0, 1500, 200);
    light.castShadow = true;
    light.shadow = newTHREE.LightShadow(newTHREE.PerspectiveCamera(70, 1, 200, 2000));
    light.shadow.bias = -0.000222;
    light.shadow.mapSize.width = 1024;
    light.shadow.mapSize.height = 1024;
    scene.add(light);
  }

  functionaddAmbientLight() {
    var ambientLight = newTHREE.AmbientLight(0x404040);
    scene.add(ambientLight);
  }

  functionaddHemisphereLight() {
    var hemisphereLight = newTHREE.HemisphereLight(0xffffbb, 0x080820, 1);
    scene.add(hemisphereLight);
  }

  functionaddRenderer() {
    renderer = newTHREE.WebGLRenderer({
      antialias: true
    });
    renderer.setPixelRatio(window.devicePixelRatio);
    renderer.setSize(window.innerWidth, window.innerHeight);
    renderer.shadowMap.enabled = true;
    container.appendChild(renderer.domElement);
    window.onresize = resize;
  }

  functionaddOrbitControls() {
    var controls = newTHREE.OrbitControls(camera, renderer.domElement);
  }

  functionresize() {
    var aspect = window.innerWidth / window.innerHeight;
    renderer.setSize(window.innerWidth, window.innerHeight);
    camera.aspect = aspect;
    camera.updateProjectionMatrix();
  }

  functionanimate() {
    requestAnimationFrame(animate);
    render();
  }

  functionrender() {
    renderer.render(scene, camera);
  }
})();

body {
  background: transparent;
  padding: 0;
  margin: 0;
  font-family: sans-serif;
}

#canvas {
  margin: 10px auto;
  width: 800px;
  height: 350px;
  margin-top: -44px;
}

<divid="container"></div><scriptsrc="https://threejs.org/build/three.js"></script><scriptsrc="https://threejs.org/examples/js/libs/dat.gui.min.js"></script><scriptsrc="https://threejs.org/examples/js/controls/OrbitControls.js"></script><scriptsrc="https://rawgit.com/Wilt/ThreeCSG/develop/ThreeCSG.js"></script><scriptsrc="https://threejs.org/examples/js/loaders/MTLLoader.js"></script><scriptsrc="https://rawgit.com/mrdoob/three.js/dev/examples/js/loaders/LoaderSupport.js"></script><scriptsrc="https://rawgit.com/mrdoob/three.js/dev/examples/js/loaders/OBJLoader2.js"></script>

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Unexpected Result Using Threecsg

Solution 1:

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