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399 lines
18 KiB
399 lines
18 KiB
3 years ago
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<!DOCTYPE html><html lang="en"><head>
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<meta charset="utf-8">
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<title>VR - 3DOF Point to Select</title>
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<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
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<meta name="twitter:card" content="summary_large_image">
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<meta name="twitter:site" content="@threejs">
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<meta name="twitter:title" content="Three.js – VR - 3DOF Point to Select">
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<meta property="og:image" content="https://threejs.org/files/share.png">
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<link rel="shortcut icon" href="/files/favicon_white.ico" media="(prefers-color-scheme: dark)">
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<link rel="shortcut icon" href="/files/favicon.ico" media="(prefers-color-scheme: light)">
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<link rel="stylesheet" href="/manual/resources/lesson.css">
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<link rel="stylesheet" href="/manual/resources/lang.css">
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<!-- Import maps polyfill -->
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<!-- Remove this when import maps will be widely supported -->
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<script async src="https://unpkg.com/es-module-shims@1.3.6/dist/es-module-shims.js"></script>
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<script type="importmap">
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{
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"imports": {
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"three": "../../build/three.module.js"
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}
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}
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</script>
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</head>
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<body>
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<div class="container">
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<div class="lesson-title">
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<h1>VR - 3DOF Point to Select</h1>
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</div>
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<div class="lesson">
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<div class="lesson-main">
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<p><strong>NOTE: The examples on this page require a VR capable
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device with a pointing device. Without one they won't work. See <a href="webxr.html">this article</a>
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as to why</strong></p>
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<p>In the <a href="webxr-look-to-select.html">previous article</a> we went over
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a very simple VR example where we let the user choose things by
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pointing via looking. In this article we will take it one step further
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and let the user choose with a pointing device </p>
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<p>Three.js makes is relatively easy by providing 2 controller objects in VR
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and tries to handle both cases of a single 3DOF controller and two 6DOF
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controllers. Each of the controllers are <a href="/docs/#api/en/core/Object3D"><code class="notranslate" translate="no">Object3D</code></a> objects which give
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the orientation and position of that controller. They also provide
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<code class="notranslate" translate="no">selectstart</code>, <code class="notranslate" translate="no">select</code> and <code class="notranslate" translate="no">selectend</code> events when the user starts pressing,
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is pressing, and stops pressing (ends) the "main" button on the controller.</p>
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<p>Starting with the last example from <a href="webxr-look-to-select.html">the previous article</a>
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let's change the <code class="notranslate" translate="no">PickHelper</code> into a <code class="notranslate" translate="no">ControllerPickHelper</code>.</p>
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<p>Our new implementation will emit a <code class="notranslate" translate="no">select</code> event that gives us the object that was picked
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so to use it we'll just need to do this.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">const pickHelper = new ControllerPickHelper(scene);
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pickHelper.addEventListener('select', (event) => {
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event.selectedObject.visible = false;
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const partnerObject = meshToMeshMap.get(event.selectedObject);
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partnerObject.visible = true;
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});
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</pre>
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<p>Remember from our previous code <code class="notranslate" translate="no">meshToMeshMap</code> maps our boxes and spheres to
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each other so if we have one we can look up its partner through <code class="notranslate" translate="no">meshToMeshMap</code>
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so here we're just hiding the selected object and un-hiding its partner.</p>
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<p>As for the actual implementation of <code class="notranslate" translate="no">ControllerPickHelper</code>, first we need
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to add the VR controller objects to the scene and to those add some 3D lines
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we can use to display where the user is pointing. We save off both the controllers
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and the their lines.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">class ControllerPickHelper {
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constructor(scene) {
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const pointerGeometry = new THREE.BufferGeometry().setFromPoints([
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new THREE.Vector3(0, 0, 0),
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new THREE.Vector3(0, 0, -1),
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]);
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this.controllers = [];
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for (let i = 0; i < 2; ++i) {
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const controller = renderer.xr.getController(i);
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scene.add(controller);
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const line = new THREE.Line(pointerGeometry);
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line.scale.z = 5;
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controller.add(line);
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this.controllers.push({controller, line});
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}
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}
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}
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</pre>
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<p>Without doing anything else this alone would give us 1 or 2 lines in the scene
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showing where the user's pointing devices are and which way they are pointing.</p>
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<p>One problem we have though, we don't want have our <code class="notranslate" translate="no">RayCaster</code> pick the line itself
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so an easy solution is separate the objects we wanted to be able to pick from the
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objects we don't by parenting them under another <a href="/docs/#api/en/core/Object3D"><code class="notranslate" translate="no">Object3D</code></a>.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">const scene = new THREE.Scene();
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+// object to put pickable objects on so we can easily
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+// separate them from non-pickable objects
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+const pickRoot = new THREE.Object3D();
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+scene.add(pickRoot);
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...
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function makeInstance(geometry, color, x) {
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const material = new THREE.MeshPhongMaterial({color});
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const cube = new THREE.Mesh(geometry, material);
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- scene.add(cube);
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+ pickRoot.add(cube);
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...
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</pre>
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<p>Next let's add some code to pick from the controllers. This is the first time
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we've picked with something not the camera. In our <a href="picking.html">article on picking</a>
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the user uses the mouse or finger to pick which means picking comes from the camera
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into the screen. In <a href="webxr-look-to-select.html">the previous article</a> we
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were picking based on which way the user is looking so again that comes from the
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camera. This time though we're picking from the position of the controllers so
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we're not using the camera.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">class ControllerPickHelper {
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constructor(scene) {
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+ this.raycaster = new THREE.Raycaster();
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+ this.objectToColorMap = new Map();
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+ this.controllerToObjectMap = new Map();
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+ this.tempMatrix = new THREE.Matrix4();
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const pointerGeometry = new THREE.BufferGeometry().setFromPoints([
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new THREE.Vector3(0, 0, 0),
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new THREE.Vector3(0, 0, -1),
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]);
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this.controllers = [];
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for (let i = 0; i < 2; ++i) {
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const controller = renderer.xr.getController(i);
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scene.add(controller);
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const line = new THREE.Line(pointerGeometry);
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line.scale.z = 5;
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controller.add(line);
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this.controllers.push({controller, line});
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}
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}
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+ update(pickablesParent, time) {
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+ this.reset();
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+ for (const {controller, line} of this.controllers) {
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+ // cast a ray through the from the controller
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+ this.tempMatrix.identity().extractRotation(controller.matrixWorld);
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+ this.raycaster.ray.origin.setFromMatrixPosition(controller.matrixWorld);
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+ this.raycaster.ray.direction.set(0, 0, -1).applyMatrix4(this.tempMatrix);
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+ // get the list of objects the ray intersected
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+ const intersections = this.raycaster.intersectObjects(pickablesParent.children);
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+ if (intersections.length) {
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+ const intersection = intersections[0];
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+ // make the line touch the object
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+ line.scale.z = intersection.distance;
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+ // pick the first object. It's the closest one
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+ const pickedObject = intersection.object;
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+ // save which object this controller picked
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+ this.controllerToObjectMap.set(controller, pickedObject);
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+ // highlight the object if we haven't already
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+ if (this.objectToColorMap.get(pickedObject) === undefined) {
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+ // save its color
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+ this.objectToColorMap.set(pickedObject, pickedObject.material.emissive.getHex());
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+ // set its emissive color to flashing red/yellow
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+ pickedObject.material.emissive.setHex((time * 8) % 2 > 1 ? 0xFF2000 : 0xFF0000);
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+ }
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+ } else {
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+ line.scale.z = 5;
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+ }
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+ }
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+ }
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}
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</pre>
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<p>Like before we use a <a href="/docs/#api/en/core/Raycaster"><code class="notranslate" translate="no">Raycaster</code></a> but this time we take the ray from the controller.
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Our previous <code class="notranslate" translate="no">PickHelper</code> there was only one thing picking but here we have up to 2
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controllers, one for each hand. We save off which object each controller is
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looking at in <code class="notranslate" translate="no">controllerToObjectMap</code>. We also save off the original emissive color in
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<code class="notranslate" translate="no">objectToColorMap</code> and we make the line long enough to touch whatever it's pointing at.</p>
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<p>We need to add some code to reset these settings every frame.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">class ControllerPickHelper {
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...
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+ _reset() {
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+ // restore the colors
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+ this.objectToColorMap.forEach((color, object) => {
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+ object.material.emissive.setHex(color);
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+ });
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+ this.objectToColorMap.clear();
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+ this.controllerToObjectMap.clear();
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+ }
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update(pickablesParent, time) {
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+ this._reset();
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...
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}
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</pre>
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<p>Next we want to emit a <code class="notranslate" translate="no">select</code> event when the user clicks the controller.
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To do that we can extend three.js's <a href="/docs/#api/en/core/EventDispatcher"><code class="notranslate" translate="no">EventDispatcher</code></a> and then we'll check
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when we get a <code class="notranslate" translate="no">select</code> event from the controller, then if that controller
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is pointing at something we emit what that controller is pointing at
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as our own <code class="notranslate" translate="no">select</code> event.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">-class ControllerPickHelper {
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+class ControllerPickHelper extends THREE.EventDispatcher {
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constructor(scene) {
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+ super();
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this.raycaster = new THREE.Raycaster();
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this.objectToColorMap = new Map(); // object to save color and picked object
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this.controllerToObjectMap = new Map();
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this.tempMatrix = new THREE.Matrix4();
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const pointerGeometry = new THREE.BufferGeometry().setFromPoints([
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new THREE.Vector3(0, 0, 0),
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new THREE.Vector3(0, 0, -1),
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]);
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this.controllers = [];
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for (let i = 0; i < 2; ++i) {
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const controller = renderer.xr.getController(i);
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+ controller.addEventListener('select', (event) => {
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+ const controller = event.target;
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+ const selectedObject = this.controllerToObjectMap.get(controller);
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+ if (selectedObject) {
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+ this.dispatchEvent({type: 'select', controller, selectedObject});
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+ }
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+ });
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scene.add(controller);
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const line = new THREE.Line(pointerGeometry);
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line.scale.z = 5;
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controller.add(line);
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this.controllers.push({controller, line});
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}
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}
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}
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</pre>
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<p>All that is left is to call <code class="notranslate" translate="no">update</code> in our render loop</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">function render(time) {
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...
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+ pickHelper.update(pickablesParent, time);
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renderer.render(scene, camera);
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}
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</pre>
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<p>and assuming you have a VR device with a controller you should
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be able to use the controllers to pick things.</p>
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<p></p><div translate="no" class="threejs_example_container notranslate">
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<div><iframe class="threejs_example notranslate" translate="no" style=" " src="/manual/examples/resources/editor.html?url=/manual/examples/webxr-point-to-select.html"></iframe></div>
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<a class="threejs_center" href="/manual/examples/webxr-point-to-select.html" target="_blank">click here to open in a separate window</a>
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</div>
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<p></p>
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<p>And what if we wanted to be able to move the objects?</p>
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<p>That's relatively easy. Let's move our controller 'select' listener
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code out into a function so we can use it for more than one thing.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">class ControllerPickHelper extends THREE.EventDispatcher {
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constructor(scene) {
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super();
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...
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this.controllers = [];
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+ const selectListener = (event) => {
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+ const controller = event.target;
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+ const selectedObject = this.controllerToObjectMap.get(event.target);
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+ if (selectedObject) {
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+ this.dispatchEvent({type: 'select', controller, selectedObject});
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+ }
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+ };
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for (let i = 0; i < 2; ++i) {
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const controller = renderer.xr.getController(i);
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- controller.addEventListener('select', (event) => {
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- const controller = event.target;
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- const selectedObject = this.controllerToObjectMap.get(event.target);
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- if (selectedObject) {
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- this.dispatchEvent({type: 'select', controller, selectedObject});
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- }
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- });
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+ controller.addEventListener('select', selectListener);
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...
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</pre>
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<p>Then let's use it for both <code class="notranslate" translate="no">selectstart</code> and <code class="notranslate" translate="no">select</code></p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">class ControllerPickHelper extends THREE.EventDispatcher {
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constructor(scene) {
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super();
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...
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this.controllers = [];
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const selectListener = (event) => {
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const controller = event.target;
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const selectedObject = this.controllerToObjectMap.get(event.target);
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if (selectedObject) {
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- this.dispatchEvent({type: 'select', controller, selectedObject});
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+ this.dispatchEvent({type: event.type, controller, selectedObject});
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}
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};
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for (let i = 0; i < 2; ++i) {
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const controller = renderer.xr.getController(i);
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controller.addEventListener('select', selectListener);
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controller.addEventListener('selectstart', selectListener);
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...
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</pre>
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<p>and let's also pass on the <code class="notranslate" translate="no">selectend</code> event which three.js sends out
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when you user lets of the button on the controller.</p>
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<pre class="prettyprint showlinemods notranslate lang-js" translate="no">class ControllerPickHelper extends THREE.EventDispatcher {
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constructor(scene) {
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super();
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...
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this.controllers = [];
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const selectListener = (event) => {
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const controller = event.target;
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const selectedObject = this.controllerToObjectMap.get(event.target);
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if (selectedObject) {
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this.dispatchEvent({type: event.type, controller, selectedObject});
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
+ const endListener = (event) => {
|
||
|
|
+ const controller = event.target;
|
||
|
|
+ this.dispatchEvent({type: event.type, controller});
|
||
|
|
+ };
|
||
|
|
|
||
|
|
for (let i = 0; i < 2; ++i) {
|
||
|
|
const controller = renderer.xr.getController(i);
|
||
|
|
controller.addEventListener('select', selectListener);
|
||
|
|
controller.addEventListener('selectstart', selectListener);
|
||
|
|
+ controller.addEventListener('selectend', endListener);
|
||
|
|
|
||
|
|
...
|
||
|
|
</pre>
|
||
|
|
<p>Now let's change the code so when we get a <code class="notranslate" translate="no">selectstart</code> event we'll
|
||
|
|
remove the selected object from the scene and make it a child of the controller.
|
||
|
|
This means it will move with the controller. When we get a <code class="notranslate" translate="no">selectend</code>
|
||
|
|
event we'll put it back in the scene.</p>
|
||
|
|
<pre class="prettyprint showlinemods notranslate lang-js" translate="no">const pickHelper = new ControllerPickHelper(scene);
|
||
|
|
-pickHelper.addEventListener('select', (event) => {
|
||
|
|
- event.selectedObject.visible = false;
|
||
|
|
- const partnerObject = meshToMeshMap.get(event.selectedObject);
|
||
|
|
- partnerObject.visible = true;
|
||
|
|
-});
|
||
|
|
|
||
|
|
+const controllerToSelection = new Map();
|
||
|
|
+pickHelper.addEventListener('selectstart', (event) => {
|
||
|
|
+ const {controller, selectedObject} = event;
|
||
|
|
+ const existingSelection = controllerToSelection.get(controller);
|
||
|
|
+ if (!existingSelection) {
|
||
|
|
+ controllerToSelection.set(controller, {
|
||
|
|
+ object: selectedObject,
|
||
|
|
+ parent: selectedObject.parent,
|
||
|
|
+ });
|
||
|
|
+ controller.attach(selectedObject);
|
||
|
|
+ }
|
||
|
|
+});
|
||
|
|
+
|
||
|
|
+pickHelper.addEventListener('selectend', (event) => {
|
||
|
|
+ const {controller} = event;
|
||
|
|
+ const selection = controllerToSelection.get(controller);
|
||
|
|
+ if (selection) {
|
||
|
|
+ controllerToSelection.delete(controller);
|
||
|
|
+ selection.parent.attach(selection.object);
|
||
|
|
+ }
|
||
|
|
+});
|
||
|
|
</pre>
|
||
|
|
<p>When an object is selected we save off that object and its
|
||
|
|
original parent. When the user is done we can put the object back.</p>
|
||
|
|
<p>We use the <a href="/docs/#api/en/core/Object3D.attach"><code class="notranslate" translate="no">Object3D.attach</code></a> to re-parent
|
||
|
|
the selected objects. These functions let us change the parent
|
||
|
|
of an object without changing its orientation and position in the
|
||
|
|
scene. </p>
|
||
|
|
<p>And with that we should be able to move the objects around with a 6DOF
|
||
|
|
controller or at least change their orientation with a 3DOF controller</p>
|
||
|
|
<p></p><div translate="no" class="threejs_example_container notranslate">
|
||
|
|
<div><iframe class="threejs_example notranslate" translate="no" style=" " src="/manual/examples/resources/editor.html?url=/manual/examples/webxr-point-to-select-w-move.html"></iframe></div>
|
||
|
|
<a class="threejs_center" href="/manual/examples/webxr-point-to-select-w-move.html" target="_blank">click here to open in a separate window</a>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
<p></p>
|
||
|
|
<p>To be honest I'm not 100% sure this <code class="notranslate" translate="no">ControllerPickHelper</code> is
|
||
|
|
the best way to organize the code but it's useful to demonstrating
|
||
|
|
the various parts of getting something simple working in VR
|
||
|
|
in three.js</p>
|
||
|
|
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
<script src="/manual/resources/prettify.js"></script>
|
||
|
|
<script src="/manual/resources/lesson.js"></script>
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
</body></html>
|