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问使用ThreeCSG的意外结果
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Stack Overflow用户

提问于 2017-12-14 17:47:52

回答 1查看 450关注 0票数 2

我正在试验ThreeCSG库，并试图将球体或法线几何替换为定制的形状，在本例中是3js示例中的心脏形状。

不幸的是，我在面对镜头的一侧得到了一个奇怪的结果。下面是一个代码示例：

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

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

		createHeartMesh();
    createDieCutHandle();
    
    // Creates a CSG cut on the cube based on the passed mesh
    createCSGDiecutHandle();
  }

  function createDieCutHandle() {
    var cubeGeo = new THREE.CubeGeometry(250, 250, 250);
    var mesh = new THREE.Mesh(cubeGeo)
    mesh.position.x = -500;
    scene.add(mesh);
  }
  
  function createCSGDiecutHandle() {
  	var cubeGeo = new THREE.CubeGeometry(250, 250, 250);
    var cubeMesh = new THREE.Mesh(cubeGeo);
    var cubeBSP = new ThreeBSP(cubeMesh);
   
    // Need geometry of the mesh to cut
    var heartShape = getHeartShape();
    var heartGeo = getHeartGeometry(heartShape);
    var meshToCut =  new THREE.Mesh( heartGeo );
    meshToCut.scale.set(10,10,10);
    meshToCut.position.z -= 80;
    var meshToCutBsp = new ThreeBSP(meshToCut)
   
    // var resultBsp = cubeBSP.union(meshToCutBsp);
    var resultBsp = cubeBSP.subtract(meshToCutBsp);
    // var resultBsp = cubeBSP.intersect(meshToCutBsp);
		
    var resultMesh = resultBsp.toMesh(new THREE.MeshLambertMaterial({flatShading: true}));
    resultMesh.geometry.computeVertexNormals();
    scene.add(resultMesh);
  }

	function getHeartShape() {
  	var x = 5, y = 10;
    var heartShape = new THREE.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);
    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;
  }
  
  function getHeartGeometry(heartShape) {
  	var extrudeSettings = {
      steps: 2,
      amount: 16,
      bevelEnabled: true,
      bevelThickness: 5,
      bevelSize: 1,
      bevelSegments: 1
    };
		return new THREE.ExtrudeBufferGeometry( heartShape, extrudeSettings );
  }

  function createHeartMesh() {
    var heartShape = getHeartShape();
		var geometry = getHeartGeometry(heartShape);
    var material = new THREE.MeshNormalMaterial();
    var mesh = new THREE.Mesh(geometry, material);
    mesh.position.x = -500;
    mesh.position.z = -80;
    mesh.scale.set(10, 10, 10);
    
    scene.add(mesh);
  }
  
  /**** Helper functions ****/
  function computeBoundingBox(mesh) {
    var box = new THREE.Box3().setFromObject(mesh);
    var size = box.getSize();

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

  /**** Basic Scene Setup ****/
  function initScene() {
    scene = new THREE.Scene();
    scene.background = new THREE.Color(0xffffff);
  }

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

  function addGridHelper() {
    var planeGeometry = new THREE.PlaneGeometry(2000, 2000);
    planeGeometry.rotateX(-Math.PI / 2);

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

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

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

  function addLighting() {
    addHemisphereLight();
  }

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

  function addAmbientLight() {
    var ambientLight = new THREE.AmbientLight(0x404040);
    scene.add(ambientLight);
  }

  function addHemisphereLight() {
    var hemisphereLight = new THREE.HemisphereLight(0xffffbb, 0x080820, 1);
    scene.add(hemisphereLight);
  }

  function addRenderer() {
    renderer = new THREE.WebGLRenderer({
      antialias: true
    });
    renderer.setPixelRatio(window.devicePixelRatio);
    renderer.setSize(window.innerWidth, window.innerHeight);
    renderer.shadowMap.enabled = true;
    container.appendChild(renderer.domElement);
  }

  function addOrbitControls() {
    var controls = new THREE.OrbitControls(camera, renderer.domElement);
  }

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

  function render() {
    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;
}

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

左边的立方体只是一个从立方体内部凸出的心脏几何图形--它们不是连接在一起的，它们只是有着相同的位置。

右边的是左的CSG版本，但我试图从立方体中减去心脏。面对镜头的那一面是错误的，因为网眼的那一边似乎在往下渗出，而后面的那一边，如果你看过去的话，是非常好的。

是什么导致了这种行为？我尝试添加属性side: THREE.DoubleSide，但是它没有解决这个问题。

我也看了这个问题，这里，并尝试调用updateMatrix()的心脏网格，但它没有影响。

谢谢

javascript

three.js

回答 1

Stack Overflow用户

回答已采纳

发布于 2017-12-19 18:35:31

ThreeCSG不能正确地减去凹面网格。但有一个解决办法，因为两半的心脏或凸起。

你可以从长方体中减去心脏的右半部分：

function getHeartShapeRight() {
    var x = 5, y = 10;
    var heartShape = new THREE.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 cuboid
var cubeGeoR = new THREE.CubeGeometry(125, 250, 250);
var cubeMeshR = new THREE.Mesh(cubeGeoR);
cubeMeshR.position.x += 62.5;
var cubeBSPR = new ThreeBSP(cubeMeshR);

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

// right subtract
var meshToCutBspR = new ThreeBSP(meshToCutR);
var resultBspR = cubeBSPR.subtract(meshToCutBspR);
var resultMeshR = resultBspR.toMesh(new THREE.MeshLambertMaterial({flatShading: true}));

你可以从长方体中减去心脏的左半部分：

function getHeartShapeLeft() {
    var x = 5, y = 10;
    var heartShape = new THREE.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 cuboid
var cubeGeoL = new THREE.CubeGeometry(125, 250, 250);
var cubeMeshL = new THREE.Mesh(cubeGeoL);
cubeMeshL.position.x -= 62.5;
var cubeBSPL = new ThreeBSP(cubeMeshL);

// left part of the heart
var heartShapeL = getHeartShapeLeft();
var heartGeoL = getHeartGeometry(heartShapeL);
var meshToCutL = new THREE.Mesh( heartGeoL );
meshToCutL.scale.set(10,10,10);
meshToCutL.position.z -= 80;
var meshToCutBspL = new ThreeBSP(meshToCutL);

// left subtract
var meshToCutBspL = new ThreeBSP(meshToCutL);
var resultBspL = cubeBSPL.subtract(meshToCutBspL);
var resultMeshL = resultBspL.toMesh(new THREE.MeshLambertMaterial({flatShading: true}));

最后，您可以创建一个由两个部分组成的联盟：

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

请参阅代码片段：

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

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

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

  function createCSGDiecutHandle() {

    // left cuboid
    var cubeGeoL = new THREE.CubeGeometry(125, 250, 250);
    var cubeMeshL = new THREE.Mesh(cubeGeoL);
    cubeMeshL.position.x -= 62.5;
    var cubeBSPL = new ThreeBSP(cubeMeshL);
   
    // left part of the heart
    var heartShapeL = getHeartShapeLeft();
    var heartGeoL = getHeartGeometry(heartShapeL);
    var meshToCutL = new THREE.Mesh( heartGeoL );
    meshToCutL.scale.set(10,10,10);
    meshToCutL.position.z -= 80;
    var meshToCutBspL = new ThreeBSP(meshToCutL);

    // left subtract
    var meshToCutBspL = new ThreeBSP(meshToCutL);
    var resultBspL = cubeBSPL.subtract(meshToCutBspL);
    var resultMeshL = resultBspL.toMesh(new THREE.MeshLambertMaterial({flatShading: true}));

    // right cuboid
    var cubeGeoR = new THREE.CubeGeometry(125, 250, 250);
    var cubeMeshR = new THREE.Mesh(cubeGeoR);
    cubeMeshR.position.x += 62.5;
    var cubeBSPR = new ThreeBSP(cubeMeshR);

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

  function getHeartShapeRight() {
    var x = 5, y = 10;
    var heartShape = new THREE.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;
  }

  function getHeartShapeLeft() {
    var x = 5, y = 10;
    var heartShape = new THREE.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;
  }

  function getHeartGeometry(heartShape) {
    var extrudeSettings = {
      steps: 2,
      amount: 16,
      bevelEnabled: true,
      bevelThickness: 5,
      bevelSize: 1,
      bevelSegments: 1
    };
        return new THREE.ExtrudeBufferGeometry( heartShape, extrudeSettings );
  }

  /**** Helper functions ****/
  function computeBoundingBox(mesh) {
    var box = new THREE.Box3().setFromObject(mesh);
    var size = box.getSize();

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

  /**** Basic Scene Setup ****/
  function initScene() {
    scene = new THREE.Scene();
    scene.background = new THREE.Color(0xffffff);
  }

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

  function addGridHelper() {
    var planeGeometry = new THREE.PlaneGeometry(2000, 2000);
    planeGeometry.rotateX(-Math.PI / 2);

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

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

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

  function addLighting() {
    addHemisphereLight();
  }

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

  function addAmbientLight() {
    var ambientLight = new THREE.AmbientLight(0x404040);
    scene.add(ambientLight);
  }

  function addHemisphereLight() {
    var hemisphereLight = new THREE.HemisphereLight(0xffffbb, 0x080820, 1);
    scene.add(hemisphereLight);
  }

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

  function addOrbitControls() {
    var controls = new THREE.OrbitControls(camera, renderer.domElement);
  }

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

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

  function render() {
    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;
}

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

票数 1

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/47819331

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