javascript - 如何在threejs中显示对象中的网格？

Question

我在场景中有水平网格助手和多边形。

有没有办法像下图那样将网格隐藏在多边形之外？

这是 JSFiddle

var camera, scene, renderer, controls, geometry, material, mesh, gridHelper, polygon;
var edges = [{
  "x": -204.87113421108512,
  "y": -150,
  "z": 350.73338884671745
}, {
  "x": -204.87113421108535,
  "y": -150,
  "z": -38.02713383973953
}, {
  "x": -83.08211641046344,
  "y": -150,
  "z": -39.62530388610881
}, {
  "x": -78.88807649109879,
  "y": -150,
  "z": -538.3155247201529
}, {
  "x": 220.63777329601388,
  "y": -150,
  "z": -535.796479191672
}, {
  "x": 220.63777329601444,
  "y": -150,
  "z": 176.94968924487634
}, {
  "x": -53.07402331399715,
  "y": -150,
  "z": 176.9496892448766
}, {
  "x": -53.07402331399726,
  "y": -150,
  "z": 350.41591086077415
}];

init();
animate();

function init() {

  scene = new THREE.Scene();
  
  renderer = new THREE.WebGLRenderer({ alpha: true, antialias: true });
	renderer.setPixelRatio(window.devicePixelRatio);
  renderer.setSize(window.innerWidth, window.innerHeight);
  renderer.setClearColor(0x555555, 1);
  renderer.sortObjects = true;
  
  document.body.appendChild(renderer.domElement);

  camera = new THREE.PerspectiveCamera(50, window.innerWidth / window.innerHeight, 1, 10000);
  scene.add(camera);
  
  camera.position.x =  1000;
 	camera.position.y =  2000;
	camera.position.z =  -1000;
  
	controls = new THREE.OrbitControls( camera );


  gridHelper = new THREE.GridHelper(1500, 30);
  gridHelper.position.y = -150;
  scene.add(gridHelper);


  var shape = new THREE.Shape();
  let firstEdge = edges[0];
  shape.moveTo(firstEdge.x, -firstEdge.z);
  const len = edges.length;
  for (let i = 1; i < len; i++) {
    shape.lineTo(edges[i].x, -edges[i].z);
  }

  shape.lineTo(firstEdge.x, -firstEdge.z);
  
  var material = new THREE.MeshBasicMaterial({
      color:0x00aa00,
      opacity:0.5,
      side:THREE.DoubleSide,
      transparent:true,
      depthTest:false
    });

  var polygonGeometry = new THREE.ShapeGeometry(shape);
  polygon = new THREE.Mesh(polygonGeometry, material);
  polygon.position.y = firstEdge.y;
  polygon.rotation.x = -Math.PI / 2.;
  polygon.name = this.name;
  scene.add(polygon);

}

function animate() {
		controls.update();
  window.requestAnimationFrame(animate);
  render();

}

function render() {

  renderer.render(scene, camera);

};

<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/three.js/100/three.js"></script>
      <script type="text/javascript" src="https://threejs.org/examples/js/controls/OrbitControls.js"></script>

如有任何建议，我们将不胜感激!

Answer 1

我使用模板缓冲区实现的结果:https://jsfiddle.net/mmalex/g3hf4zxc/

const gl = renderer.getContext();
polygon.onBeforeRender = function () {
    gl.enable(gl.STENCIL_TEST)
    gl.stencilFunc(gl.ALWAYS, 1, 0xFF);
    gl.stencilMask(0xFF);
    gl.stencilOp(gl.KEEP, gl.KEEP, gl.INCR);
}
polygon.onAfterRender = function() {
    gl.disable(gl.DEPTH_TEST);
}
polygon.renderOrder = 999;

gridHelper.onBeforeRender = function() {
    gl.enable(gl.STENCIL_TEST)
    gl.stencilMask(0x00);
    gl.stencilFunc(gl.EQUAL, 1, 0xFF);
}
gridHelper.onAfterRender = function() {
    gl.disable(gl.STENCIL_TEST)
}
gridHelper.renderOrder = 1000

不幸的是，我牺牲了网格不透明度，因为 threejs 独立地对不透明和透明对象进行排序:

.renderOrder : Number This value allows the default rendering order of scene graph objects to be overridden although opaque and transparent objects remain sorted independently. Sorting is from lowest to highest renderOrder. Default value is 0.

https://threejs.org/docs/#api/en/core/Object3D.renderOrder