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+/**
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+ * encantar.js pointer demo
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+ * @license LGPL-3.0-or-later
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+ * @author Alexandre Martins <alemartf(at)gmail.com> (https://github.com/alemart/encantar-js)
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+ */
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+
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+(function() {
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+
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+let displayMessage = true;
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+
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+const POINTER_RADIUS = 50;
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+const POINTER_COLOR = 'red';
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+const PRIMARY_POINTER_COLOR = 'lime';
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+const BACKGROUND_COLOR = 'antiquewhite';
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+const TEXT_COLOR = 'black';
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+const TEXT_FONT = '36px sans-serif';
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+const TEXT_LARGE_FONT = '96px sans-serif';
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+const TEXT_LINE_HEIGHT = 40;
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+const TWO_PI = 2.0 * Math.PI;
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+
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+/**
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+ * Render the virtual scene
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+ * @param {TrackablePointer[]} pointers
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+ * @param {Viewport} viewport
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+ * @returns {void}
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+ */
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+function render(pointers, viewport)
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+{
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+ /*
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+
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+ Check out the API reference to see the various interesting properties of a
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+ TrackablePointer! They are useful for creating all sorts of interactive
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+ experiences!
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+
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+ */
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+
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+ // get the canvas context
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+ const canvas = viewport.canvas;
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+ const ctx = canvas.getContext('2d');
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+
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+ if(!ctx)
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+ return;
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+
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+ ctx.textAlign = 'center';
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+
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+ // draw the background
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+ ctx.fillStyle = BACKGROUND_COLOR;
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+ ctx.fillRect(0, 0, canvas.width, canvas.height);
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+
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+ // display a message
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+ if(displayMessage) {
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+ ctx.fillStyle = TEXT_COLOR;
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+ ctx.font = TEXT_LARGE_FONT;
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+ ctx.fillText('Tap to begin', canvas.width / 2, canvas.height / 2);
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+
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+ if(pointers.length > 0)
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+ displayMessage = false;
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+ }
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+
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+ // render the pointers
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+ for(const pointer of pointers) {
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+ // pointer.position is given in normalized units [-1,1]x[-1,1]
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+ // we convert it to pixel coordinates (canvas space)
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+ const position = viewport.convertToPixels(pointer.position);
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+
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+ ctx.fillStyle = pointer.isPrimary ? PRIMARY_POINTER_COLOR : POINTER_COLOR;
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+ ctx.beginPath();
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+ ctx.arc(position.x, position.y, POINTER_RADIUS, 0, TWO_PI);
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+ ctx.fill();
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+ }
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+
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+ // render the texts above the pointers
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+ ctx.fillStyle = TEXT_COLOR;
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+ ctx.font = TEXT_FONT;
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+ for(const pointer of pointers) {
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+ const position = viewport.convertToPixels(pointer.position);
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+ position.y -= POINTER_RADIUS + 6 * TEXT_LINE_HEIGHT;
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+
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+ ctx.fillText('id: ' + pointer.id, position.x, position.y + 0 * TEXT_LINE_HEIGHT);
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+ ctx.fillText(pointer.phase, position.x, position.y + 1 * TEXT_LINE_HEIGHT);
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+ ctx.fillText('x: ' + pointer.position.x.toFixed(5), position.x, position.y + 2 * TEXT_LINE_HEIGHT);
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+ ctx.fillText('y: ' + pointer.position.y.toFixed(5), position.x, position.y + 3 * TEXT_LINE_HEIGHT);
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+ ctx.fillText('speed: ' + pointer.velocity.length().toFixed(5), position.x, position.y + 4 * TEXT_LINE_HEIGHT);
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+ ctx.fillText('time: ' + pointer.elapsedTime.toFixed(5), position.x, position.y + 5 * TEXT_LINE_HEIGHT);
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+ }
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+}
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+
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+/**
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+ * Start the AR session
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+ * @returns {Promise<Session>}
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+ */
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+async function startARSession()
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+{
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+ if(!AR.isSupported()) {
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+ throw new Error(
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+ 'This device is not compatible with this AR experience.\n\n' +
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+ 'User agent: ' + navigator.userAgent
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+ );
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+ }
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+
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+ const viewport = AR.Viewport({
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+ resolution: '720p',
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+ container: document.getElementById('ar-viewport'),
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+ hudContainer: document.getElementById('ar-hud')
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+ });
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+
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+ const tracker = AR.Tracker.Pointer();
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+ const source = AR.Source.Pointer();
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+
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+ const session = await AR.startSession({
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+ mode: 'immersive',
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+ viewport: viewport,
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+ trackers: [ tracker ],
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+ sources: [ source ],
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+ stats: true,
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+ });
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+
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+ return session;
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+}
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+
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+/**
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+ * Animation loop
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+ * @param {number} time
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+ * @param {Frame} frame
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+ * @returns {void}
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+ */
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+function animate(time, frame)
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+{
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+ const session = frame.session;
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+ const pointers = read(frame);
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+
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+ render(pointers, session.viewport);
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+
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+ session.requestAnimationFrame(animate);
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+}
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+
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+/**
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+ * Read the results of the tracker
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+ * @param {Frame} frame
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+ * @returns {TrackablePointer[]}
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+ */
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+function read(frame)
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+{
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+ for(const result of frame.results) {
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+ if(result.tracker.type == 'pointer-tracker') {
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+ const pointers = result.trackables;
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+ return pointers;
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+ }
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+ }
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+
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+ return [];
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+}
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+
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+/**
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+ * Start the demo
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+ * @returns {void}
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+ */
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+function main()
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+{
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+ startARSession().then(session => {
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+
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+ session.requestAnimationFrame(animate); // start the animation loop
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+
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+ }).catch(error => {
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+
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+ alert(error.message);
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+
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+ });
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+}
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+
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+document.addEventListener('DOMContentLoaded', main);
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+
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+})();
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alemart
10 mesi fa
