playcanvas/build/playcanvas/src/framework/xr/xr-image-tracking.js

PlayCanvas WebGL game engine

import { EventHandler } from '../../core/event-handler.js';
import { platform } from '../../core/platform.js';
import { XrTrackedImage } from './xr-tracked-image.js';

class XrImageTracking extends EventHandler {
		static{
				this.EVENT_ERROR = 'error';
		}
		constructor(manager){
				super(), this._supported = platform.browser && !!window.XRImageTrackingResult, this._available = false, this._images = [];
				this._manager = manager;
				if (this._supported) {
						this._manager.on('start', this._onSessionStart, this);
						this._manager.on('end', this._onSessionEnd, this);
				}
		}
		add(image, width) {
				if (!this._supported || this._manager.active) return null;
				const trackedImage = new XrTrackedImage(image, width);
				this._images.push(trackedImage);
				return trackedImage;
		}
		remove(trackedImage) {
				if (this._manager.active) return;
				const ind = this._images.indexOf(trackedImage);
				if (ind !== -1) {
						trackedImage.destroy();
						this._images.splice(ind, 1);
				}
		}
		_onSessionStart() {
				this._manager.session.getTrackedImageScores().then((images)=>{
						this._available = true;
						for(let i = 0; i < images.length; i++){
								this._images[i]._trackable = images[i] === 'trackable';
						}
				}).catch((err)=>{
						this._available = false;
						this.fire('error', err);
				});
		}
		_onSessionEnd() {
				this._available = false;
				for(let i = 0; i < this._images.length; i++){
						const image = this._images[i];
						image._pose = null;
						image._measuredWidth = 0;
						if (image._tracking) {
								image._tracking = false;
								image.fire('untracked');
						}
				}
		}
		prepareImages(callback) {
				if (this._images.length) {
						Promise.all(this._images.map((trackedImage)=>{
								return trackedImage.prepare();
						})).then((bitmaps)=>{
								callback(null, bitmaps);
						}).catch((err)=>{
								callback(err, null);
						});
				} else {
						callback(null, null);
				}
		}
		update(frame) {
				if (!this._available) return;
				const results = frame.getImageTrackingResults();
				const index = {};
				for(let i = 0; i < results.length; i++){
						index[results[i].index] = results[i];
						const trackedImage = this._images[results[i].index];
						trackedImage._emulated = results[i].trackingState === 'emulated';
						trackedImage._measuredWidth = results[i].measuredWidthInMeters;
						trackedImage._pose = frame.getPose(results[i].imageSpace, this._manager._referenceSpace);
				}
				for(let i = 0; i < this._images.length; i++){
						if (this._images[i]._tracking && !index[i]) {
								this._images[i]._tracking = false;
								this._images[i].fire('untracked');
						} else if (!this._images[i]._tracking && index[i]) {
								this._images[i]._tracking = true;
								this._images[i].fire('tracked');
						}
				}
		}
		get supported() {
				return this._supported;
		}
		get available() {
				return this._available;
		}
		get images() {
				return this._images;
		}
}

export { XrImageTracking };