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<html>
<!-- Any copyright is dedicated to the Public Domain.
http://creativecommons.org/publicdomain/zero/1.0/
-->
<head>
<title>Reticle 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>
<script module src="../../dist/webxr.js"></script>
<link rel="stylesheet" href="../common.css"/>
</head>
<body>
<div id="description">
<h2>Reticle</h2>
<h5>(click to dismiss)</h5>
<p>Place a reticle on surfaces.</p>
</div>
<button type=button id=go-button>Go</button>
<script type=module>
/*
Reticle Example shows how to find surfaces or other features and place reticle relative to them.
In a production application, you would likely want to request world geometry, rather than only
using low level hit testing, and fall back to this method if the user declines to provide
real world geometry access.
*/
// 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"
import XRInputManager from "../XRInputManager.js"
let device = null
let session = null
let eyeLevelFrameOfReference = null
let engine = null
// temporary working variables
const workingMatrix = mat4.create()
const workingVec3 = vec3.create()
var savedOrigin = [0,0,0]
var savedDirection = [0,0,-1]
var reticleParent = new THREE.Object3D()
var reticle = null
var reticleTrackedColor = new THREE.Color( 0xDDFFDD );
var reticleNotTrackedColor = new THREE.Color( 0xFF6666 );
var reticleMaterial = new THREE.MeshBasicMaterial({ color: reticleTrackedColor })
var requestNextHit = true
function initializeScene(){
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])
reticle = new THREE.Mesh(
new THREE.RingGeometry(0.04, 0.05, 36, 64),
reticleMaterial
)
reticle.geometry.applyMatrix(new THREE.Matrix4().makeRotationX(THREE.Math.degToRad(-90)))
reticleParent.add(reticle)
reticleParent.matrixAutoUpdate = false
reticleParent.visible = false
engine.scene.add(reticleParent)
}
// handle hit testing slightly differently than other samples, since we're doing
// it per frame. The "boiler plate" code below is slightly different, setting
// requestNextHit on tap instead of executing the hit test. The custom XREngineHits
// does a hit test each frame if the previous one has resolved
function handleHitResults(hits) {
let size = 0.05;
if (hits.length > 0) {
let hit = hits[0]
// convert hit matrices from head to eye level coordinate systems
session.requestFrameOfReference('head-model').then(headFrameOfReference => {
headFrameOfReference.getTransformTo(eyeLevelFrameOfReference, workingMatrix)
mat4.multiply(workingMatrix, workingMatrix, hit.hitMatrix)
const node = reticleParent
node.matrix.fromArray(workingMatrix)
reticleParent.visible = true // it starts invisible
reticle.material.color = reticleTrackedColor
node.updateMatrixWorld(true)
})
} else {
reticle.material.color = reticleNotTrackedColor
}
requestNextHit = true
}
class XREngineHits extends XREngine {
endFrame(){
if (requestNextHit) {
requestNextHit = false
session.requestFrameOfReference('head-model').then(headFrameOfReference => {
session.requestHitTest(savedOrigin, savedDirection, headFrameOfReference)
.then(handleHitResults)
.catch(err => {
console.error('Error testing hits', err)
})
})
}
}
}
////////////////////////////////////////////////////
////////////////////////////////////////////////////
// BOILER PLATE. Can you feel the plates boiling?
//
// There are slight differences between examples but largely this code is similar
//
// Create the output context where the XRSession will place composited renders
const xrCanvas = document.createElement('canvas')
xrCanvas.setAttribute('class', 'xr-canvas')
const xrContext = xrCanvas.getContext('xrpresent')
if(!xrContext){
console.error('No XR context', xrCanvas)
}
// get the XR Device
navigator.xr.requestDevice().then(xrDevice => {
device = xrDevice
}).catch(err => {
})
document.getElementById('description').addEventListener('touchstart', hideMe, {capture: true})
function hideMe(event) {
event.target.style.display = 'none'
event.stopPropagation()
}
document.getElementById('go-button').addEventListener('click', handleStartSessionRequest, true)
document.getElementById('go-button').addEventListener('touchstart', handleGoButtonTouch, true)
function handleGoButtonTouch(event) {
event.stopPropagation()
}
// handle input events from the XRInputManager
const inputManager = new XRInputManager(handleXRInput)
function handleXRInput(eventName, details){
switch(eventName){
case 'normalized-touch':
hitTestWithScreenCoordinates(...details.normalizedCoordinates)
break
default:
console.error('unknown xr input event', eventName, details)
break
}
}
function hitTestWithScreenCoordinates(normalizedX, normalizedY){
if(session === null){
console.log('No session for hit testing')
return
}
// Convert the screen coordinates into head-model origin/direction for hit testing
const [origin, direction] =
XRInputManager.convertScreenCoordinatesToRay(normalizedX, normalizedY,
engine.camera.projectionMatrix)
savedOrigin = origin
savedDirection = direction
requestNextHit = true
}
/////////////////////
// Session startup / shutdown
function handleStartSessionRequest(ev){
if(device === null){
console.error('No xr device')
return
}
if (!session) {
device.requestSession({ outputContext: xrContext })
.then(handleSessionStarted)
.catch(err => {
console.error('Session setup error', err)
})
document.getElementById('go-button').innerText = "End"
document.getElementById('go-button').style.display = "none"
} else {
session.end()
handleSessionEnded();
reticleParent.visible = false // it starts invisible
document.getElementById('description').style.display = 'block'
document.getElementById('go-button').style.display = "block"
document.getElementById('go-button').innerText = "Go"
}
}
function handleSessionEnded() {
session = null
}
function handleSessionStarted(xrSession){
session = xrSession
document.body.insertBefore(xrCanvas, document.body.firstChild)
// Create the context where we will render our 3D scene
const canvas = document.createElement('canvas')
var glContext = canvas.getContext('webgl', {
compatibleXRDevice: device
})
if(!glContext) throw new Error('Could not create a webgl context')
// Set up the base layer
session.baseLayer = new XRWebGLLayer(session, glContext)
// Create a simple test scene and renderer
// The engine's scene is in the eye-level coordinate system
// Our custom engine class does hit testing at the end of each rAF
engine = new XREngineHits(canvas, glContext)
createRootNode().then(() => {
// Kick off rendering
session.requestAnimationFrame(handleAnimationFrame)
})
initializeScene()
}
async function createRootNode() {
let headFrameOfReference = await session.requestFrameOfReference('head-model')
eyeLevelFrameOfReference = await session.requestFrameOfReference('eye-level')
// get the location of the device, and use it to create an
// anchor with the identity orientation
headFrameOfReference.getTransformTo(eyeLevelFrameOfReference, workingMatrix)
mat4.getTranslation(workingVec3, workingMatrix)
mat4.fromTranslation(workingMatrix, workingVec3)
let anchor = await session.addAnchor(workingMatrix, eyeLevelFrameOfReference)
engine.addAnchoredNode(anchor, engine.root)
return true
}
////////////////
// render loop
function handleAnimationFrame(t, frame){
if(!session || session.ended) return
session.requestAnimationFrame(handleAnimationFrame)
let pose = frame.getDevicePose(eyeLevelFrameOfReference)
if(!pose){
console.log('No pose')
return
}
engine.startFrame()
for (let view of frame.views) {
engine.preRender(
session.baseLayer.getViewport(view),
view.projectionMatrix,
pose.getViewMatrix(view)
)
engine.render()
}
engine.endFrame()
}
</script>
</body>
</html>
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