javascript
/
three.js
mirror of https://github.com/tazdij/three.js.git


			
				
					
						
						
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							<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
    <title>Three.js - Picking - RayCaster w/Transparency</title>
    <style>
    body {
        margin: 0;
    }
    #c {
        width: 100vw;
        height: 100vh;
        display: block;
    }
    </style>
  </head>
  <body>
    <canvas id="c"></canvas>
  </body>
<script src="resources/threejs/r102/three.min.js"></script>
<script>
'use strict';

/* global THREE */

function main() {
  const canvas = document.querySelector('#c');
  const renderer = new THREE.WebGLRenderer({canvas: canvas});

  const fov = 60;
  const aspect = 2;  // the canvas default
  const near = 0.1;
  const far = 200;
  const camera = new THREE.PerspectiveCamera(fov, aspect, near, far);
  camera.position.z = 30;

  const scene = new THREE.Scene();
  scene.background = new THREE.Color('white');
  const pickingScene = new THREE.Scene();
  pickingScene.background = new THREE.Color(0);

  // put the camera on a pole (parent it to an object)
  // so we can spin the pole to move the camera around the scene
  const cameraPole = new THREE.Object3D();
  scene.add(cameraPole);
  cameraPole.add(camera);

  {
    const color = 0xFFFFFF;
    const intensity = 1;
    const light = new THREE.DirectionalLight(color, intensity);
    light.position.set(-1, 2, 4);
    camera.add(light);
  }

  const boxWidth = 1;
  const boxHeight = 1;
  const boxDepth = 1;
  const geometry = new THREE.BoxGeometry(boxWidth, boxHeight, boxDepth);

  function rand(min, max) {
    if (max === undefined) {
      max = min;
      min = 0;
    }
    return min + (max - min) * Math.random();
  }

  function randomColor() {
    return `hsl(${rand(360) | 0}, ${rand(50, 100) | 0}%, 50%)`;
  }

  const loader = new THREE.TextureLoader();
  const texture = loader.load('resources/images/frame.png');

  const idToObject = {};
  const numObjects = 100;
  for (let i = 0; i < numObjects; ++i) {
    const id = i + 1;
    const material = new THREE.MeshPhongMaterial({
      color: randomColor(),
      map: texture,
      transparent: true,
      side: THREE.DoubleSide,
      alphaTest: 0.5,
    });

    const cube = new THREE.Mesh(geometry, material);
    scene.add(cube);
    idToObject[id] = cube;

    cube.position.set(rand(-20, 20), rand(-20, 20), rand(-20, 20));
    cube.rotation.set(rand(Math.PI), rand(Math.PI), 0);
    cube.scale.set(rand(3, 6), rand(3, 6), rand(3, 6));

    const pickingMaterial = new THREE.MeshPhongMaterial({
      emissive: new THREE.Color(id),
      color: new THREE.Color(0, 0, 0),
      specular: new THREE.Color(0, 0, 0),
      map: texture,
      transparent: true,
      side: THREE.DoubleSide,
      alphaTest: 0.5,
      blending: THREE.NoBlending,
    });
    const pickingCube = new THREE.Mesh(geometry, pickingMaterial);
    pickingScene.add(pickingCube);
    pickingCube.position.copy(cube.position);
    pickingCube.rotation.copy(cube.rotation);
    pickingCube.scale.copy(cube.scale);
  }

  function resizeRendererToDisplaySize(renderer) {
    const canvas = renderer.domElement;
    const width = canvas.clientWidth;
    const height = canvas.clientHeight;
    const needResize = canvas.width !== width || canvas.height !== height;
    if (needResize) {
      renderer.setSize(width, height, false);
    }
    return needResize;
  }

  class GPUPickHelper {
    constructor() {
      // create a 1x1 pixel render target
      this.pickingTexture = new THREE.WebGLRenderTarget(1, 1);
      this.pixelBuffer = new Uint8Array(4);
      this.pickedObject = null;
      this.pickedObjectSavedColor = 0;
    }
    pick(cssPosition, scene, camera, time) {
      const {pickingTexture, pixelBuffer} = this;

      // restore the color if there is a picked object
      if (this.pickedObject) {
        this.pickedObject.material.emissive.setHex(this.pickedObjectSavedColor);
        this.pickedObject = undefined;
      }

      // set the view offset to represent just a single pixel under the mouse
      const pixelRatio = renderer.getPixelRatio();
      camera.setViewOffset(
          renderer.context.drawingBufferWidth,   // full width
          renderer.context.drawingBufferHeight,  // full top
          cssPosition.x * pixelRatio | 0,        // rect x
          cssPosition.y * pixelRatio | 0,        // rect y
          1,                                     // rect width
          1,                                     // rect height
      );
      // render the scene
      renderer.setRenderTarget(pickingTexture);
      renderer.render(scene, camera);
      renderer.setRenderTarget(null);
      // clear the view offset so rendering returns to normal
      camera.clearViewOffset();
      //read the pixel
      renderer.readRenderTargetPixels(
          pickingTexture,
          0,   // x
          0,   // y
          1,   // width
          1,   // height
          pixelBuffer);

      const id =
          (pixelBuffer[0] << 16) |
          (pixelBuffer[1] <<  8) |
          (pixelBuffer[2]      );

      const intersectedObject = idToObject[id];
      if (intersectedObject) {
        // pick the first object. It's the closest one
        this.pickedObject = intersectedObject;
        // save its color
        this.pickedObjectSavedColor = this.pickedObject.material.emissive.getHex();
        // set its emissive color to flashing red/yellow
        this.pickedObject.material.emissive.setHex((time * 8) % 2 > 1 ? 0xFFFF00 : 0xFF0000);
      }
    }
  }

  const pickPosition = {x: 0, y: 0};
  const pickHelper = new GPUPickHelper();
  clearPickPosition();

  function render(time) {
    time *= 0.001;  // convert to seconds;

    if (resizeRendererToDisplaySize(renderer)) {
      const canvas = renderer.domElement;
      camera.aspect = canvas.clientWidth / canvas.clientHeight;
      camera.updateProjectionMatrix();
    }

    cameraPole.rotation.y = time * .1;

    pickHelper.pick(pickPosition, pickingScene, camera, time);

    renderer.render(scene, camera);

    requestAnimationFrame(render);
  }
  requestAnimationFrame(render);

  function setPickPosition(event) {
    pickPosition.x = event.clientX;
    pickPosition.y = event.clientY;
  }

  function clearPickPosition() {
    // unlike the mouse which always has a position
    // if the user stops touching the screen we want
    // to stop picking. For now we just pick a value
    // unlikely to pick something
    pickPosition.x = -100000;
    pickPosition.y = -100000;
  }

  window.addEventListener('mousemove', setPickPosition);
  window.addEventListener('mouseout', clearPickPosition);
  window.addEventListener('mouseleave', clearPickPosition);

  window.addEventListener('touchstart', (event) => {
    // prevent the window from scrolling
    event.preventDefault();
    setPickPosition(event.touches[0]);
  }, {passive: false});

  window.addEventListener('touchmove', (event) => {
    setPickPosition(event.touches[0]);
  });

  window.addEventListener('touchend', clearPickPosition);
}

main();
</script>
</html>