webxr-ios-js/examples/hit_test/index.html at master · MozillaReality/webxr-ios-js · GitHub

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<html>
	<!-- Any copyright is dedicated to the Public Domain.
			http://creativecommons.org/publicdomain/zero/1.0/
	-->
	<head>
		<title>Hit test example</title>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
		<script src="../libs/three/three.min.js"></script>
		<link rel="stylesheet" href="../common.css"/>
	</head>
	<body>
		<div id="description">
			<h2>Hit Test Anchors</h2>
			<p>Anchor boxes by create XRAnchors from XRHitTest results.</p>
		</div>
		<button type=button id=go-button disabled>Go</button>
		<script type=module>
			// some dependencies and utilities
			import * as mat4 from '../libs/gl-matrix/mat4.js';
			import * as vec3 from '../libs/gl-matrix/vec3.js';

			import XREngine from '../XREngine.js';

			let session = null;
			let viewerReferenceSpace = null;
			let localReferenceSpace = null;
			let engine = null;

			let hitTestSource = null;
			let inputSource = null;
			let hitTestSourceFrameNum = 0;
			let isSelecting = false;

			// temporary working variables
			const workingMatrix = mat4.create();
			const workingVec3 = vec3.create();

			const goButton = document.getElementById('go-button');

			const initXR = () => {
				if (navigator.xr) {
					navigator.xr.isSessionSupported('immersive-ar').then(supported => {
						if (supported) {
							goButton.disabled = false;
							goButton.addEventListener('click', onButtonClick);
						} else {
							goButton.initText = 'No WebXR AR support';
						}
					});
				} else {
					goButton.initText = 'No WebXR support';
				}
			};

			const onButtonClick = event => {
				if (!session) {
					navigator.xr.requestSession('immersive-ar', {requiredFeatures: ['hit-test']})
						.then(xrSession => {
							initSession(xrSession);
							goButton.innerText = 'End';
						}).catch(err => {
							console.error('Session setup error', err);
						});
				} else {
					session.end();
				}
			};

			const initSession = async xrSession => {
				session = xrSession;
				session.addEventListener('end', onSessionEnd);
				session.addEventListener('select', onSelect);
				session.addEventListener('inputsourceschange', onInputSourcesChange);

				localReferenceSpace = await session.requestReferenceSpace('local');
				viewerReferenceSpace = await session.requestReferenceSpace('viewer');

				// Create the context where we will render our 3D scene
				const canvas = document.createElement('canvas');
				const context = canvas.getContext('webgl', {
					xrCompatible: true
				});

				if (!context) throw new Error('Could not create a webgl context');

				// Set up the base layer
				session.updateRenderState({baseLayer: new XRWebGLLayer(session, context)});

				// Create a simple test scene and renderer
				// The engine's scene is in the eye-level coordinate system
				engine = new XREngine(canvas, context);

				// get the location of the device, and use it to create an
				// anchor with the identity orientation
				session.requestAnimationFrame(async (t, frame) => {
					mat4.copy(workingMatrix, frame.getPose(localReferenceSpace, viewerReferenceSpace).transform.matrix);
					mat4.getTranslation(workingVec3, workingMatrix);
					mat4.fromTranslation(workingMatrix, workingVec3);

					const anchor = await frame.addAnchor(workingMatrix, localReferenceSpace);
					engine.addAnchoredNode(anchor, engine.root);

					// Kick off rendering
					session.requestAnimationFrame(handleAnimationFrame);
				});

				// initialize scene

				engine.addAmbientLight();
				engine.addDirectionalLight();

				// Add a box and axis at the origin of the eye-level coordinate system
				// for debugging by uncommenting these lines
				// engine.addBox([0, 0, 0], [0.025, 0.025, 0.025], 0x44ff44)
				// engine.addAxesHelper([0,0,0], [0.2,0.2,0.2])
			};

			const onSessionEnd = event => {
				clearHitTestSource();
				session = null;
				inputSource = null;
				viewerReferenceSpace = null;
				localReferenceSpace = null;
				goButton.innerText = 'Go';
			};

			const onInputSourcesChange = event => {
				if (inputSource && event.removed.includes(inputSource)) {
					inputSource = null;
				}
				if (!inputSource && event.added.length > 0) {
					inputSource = event.added[0];
				}
			};

			const onSelect = event => {
				clearHitTestSource();
				isSelecting = true;
			};

			const clearHitTestSource = () => {
				if (hitTestSource) {
					hitTestSource.cancel();
				}
				hitTestSource = null;
				hitTestSourceFrameNum = 0;
			};

			// Creates a box used to indicate the location of an anchor offset

			const createBox = () => {
				const group = new THREE.Group();
				const geometry = new THREE.BoxBufferGeometry(0.1, 0.1, 0.1);
				const color = new THREE.Color(0xffffff);
				color.setHex(Math.random() * 0xffffff);
				const material = new THREE.MeshPhongMaterial({color: color});
				const mesh = new THREE.Mesh(geometry, material);
				const outlineMaterial = new THREE.MeshBasicMaterial({color: 0x00ff00, side: THREE.BackSide});
				const outlineMesh = new THREE.Mesh(geometry, outlineMaterial);

				mesh.position.set(0, 0.05, 0);
				outlineMesh.position.set(0, 0.05, 0);
				outlineMesh.scale.multiplyScalar(1.05);

				group.add(mesh);
				group.add(outlineMesh);

				return group;
			};

			// Create offset ray for hit test from the relative transform
			// between viewerPose and inputPose. There may be a room to optimize.
			const createOffsetRay = (viewerPose, inputPose) => {
				const offsetMatrix = mat4.multiply(mat4.create(), viewerPose.transform.matrix, inputPose.transform.matrix);
				const direction = vec3.fromValues(0.0, 0.0, -0.2);
				vec3.transformMat4(direction, direction, offsetMatrix);
				vec3.normalize(direction, direction);
				const offsetDirection = {
					x: direction[0],
					y: direction[1],
					z: direction[2],
					w: 0.0
				};
				const offsetOrigin = {x: 0, y: 0, z: 0, w: 1.0};
				return new XRRay(offsetOrigin, offsetDirection);
			};

			// render loop

			const handleAnimationFrame = (t, frame) => {
				if (!session || session.ended) return;

				session.requestAnimationFrame(handleAnimationFrame);

				const viewerPose = frame.getViewerPose(localReferenceSpace);
				if (!viewerPose) {
					console.log('No viewer pose');
					return;
				}

				// Create HitTest Source. Calculating offset ray from the relative transform
				// between viewerPose and inputPose so we need to do in animation frame.
				if (isSelecting && inputSource) {
					const inputPose = frame.getPose(inputSource.targetRaySpace, localReferenceSpace);
					const offsetRay = createOffsetRay(viewerPose, inputPose);
					session.requestHitTestSource({space: viewerReferenceSpace, offsetRay: offsetRay}).then(xrHitTestSource => {
						hitTestSource = xrHitTestSource;
						hitTestSourceFrameNum = 0;
					});
					isSelecting = false;
				}

				if (hitTestSource) {
					const results = frame.getHitTestResults(hitTestSource);
					if (results.length > 0) {
						const result = results[0];
						const pose = result.getPose(localReferenceSpace);
						if (pose) {
							frame.addAnchor(pose.transform.matrix, localReferenceSpace).then(anchor => {
								engine.addAnchoredNode(anchor, createBox());
							}).catch(err => {
								console.error('Error adding anchor', err);
							});
						}
						clearHitTestSource();
					} else {
						hitTestSourceFrameNum++;
						// Dispose hit test source if we don't get any hit test result
						// in arbitary frame nums
						if (hitTestSourceFrameNum > 2) {
							clearHitTestSource();
						}
					}
				}

				engine.startFrame();
				for (const view of viewerPose.views) {
					engine.preRender(
						session.renderState.baseLayer.getViewport(view),
						view.projectionMatrix,
						view.transform.matrix
					);
					engine.render();
				}
				engine.endFrame();
			};

			initXR();
		</script>
	</body>
</html>