speedy-vision
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GPU-accelerated Computer Vision for JavaScript
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HTML
<!--
speedy-vision.js
GPU-accelerated Computer Vision for JavaScript
Copyright 2020-2022 Alexandre Martins <alemartf(at)gmail.com>
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
alpha-blending.html
Alpha blending
-->
<html>
<head>
<meta charset="utf-8">
<meta name="description" content="speedy-vision.js: GPU-accelerated Computer Vision for JavaScript">
<meta name="author" content="Alexandre Martins">
<title>Alpha blending</title>
<script src="../dist/speedy-vision.js"></script>
<link href="style.css" rel="stylesheet">
</head>
<body>
<h1>Alpha blending</h1>
<form autocomplete="off">
<div>
<label for="alpha">Alpha</label>
<input type="range" min="0.0" max="1.0" value="0.5" step="0.01" id="alpha">
</div>
</form>
<video
src="../assets/flying-eagle.webm"
poster="../assets/loading.jpg"
preload="auto"
loop muted controls autoplay hidden
title="Free video by Cinema Professionals, https://www.pexels.com/pt-br/video/assistindo-a-aguia-voar-3635378/">
</video>
<img src="../assets/speedy-wall.jpg" title="Image by Bride of Frankenstein (CC-BY)" hidden>
<div>
<span id="status"></span>
<canvas id="canvas-demo"></canvas>
</div>
<script>
window.onload = async function()
{
// Form elements
const alpha = document.getElementById('alpha');
// Load media
const image = document.querySelector('img');
const video = document.querySelector('video');
const media = [
await Speedy.load(video),
await Speedy.load(image),
];
video.play();
// Dimensions of the display canvas
const width = Math.max(media[0].width, media[1].width);
const height = Math.max(media[0].height, media[1].height);
// Setup an animated canvas
const animatedCanvas = createCanvas(width, height);
(() => {
const [ background, sprite ] = media;
const position = Speedy.Point2(0, 0);
const speed = Speedy.Vector2(100, 100);
let lastTime = Date.now();
async function animate()
{
// update timer
const now = Date.now();
const dt = 0.001 * (now - lastTime);
lastTime = now;
// move sprite
position.x += speed.x * dt;
position.y += speed.y * dt;
if(position.x + sprite.width > width)
speed.x = -Math.abs(speed.x);
else if(position.x < 0)
speed.x = Math.abs(speed.x);
if(position.y + sprite.height > height)
speed.y = -Math.abs(speed.y);
else if(position.y < 0)
speed.y = Math.abs(speed.y);
// draw animation
draw(background, animatedCanvas);
draw(sprite, animatedCanvas, position.x, position.y);
requestAnimationFrame(animate);
}
animate();
animatedCanvas.hidden = true;
})();
// Setup the pipeline
const pipeline = Speedy.Pipeline(); // create the pipeline and the nodes
const videoSource = Speedy.Image.Source();
const animationSource = Speedy.Image.Source();
const mixer = Speedy.Image.Mixer();
const sink = Speedy.Image.Sink();
videoSource.media = media[0]; // set the media source
animationSource.media = await Speedy.load(animatedCanvas);
videoSource.output().connectTo(mixer.input('in1')); // connect the nodes
animationSource.output().connectTo(mixer.input('in0'));
mixer.output().connectTo(sink.input());
pipeline.init(videoSource, animationSource, mixer, sink); // add the nodes to the pipeline
// Main loop
(function() {
const canvas = document.getElementById('canvas-demo');
canvas.width = width;
canvas.height = height;
canvas.title = video.title + ' | ' + image.title;
let blended = null, frameReady = false
async function update()
{
mixer.alpha = Number(alpha.value);
mixer.beta = 1 - mixer.alpha;
mixer.gamma = 0;
const result = await pipeline.run();
blended = result.image;
frameReady = true;
setTimeout(update, 1000 / 60);
}
update();
function render()
{
if(frameReady) {
draw(blended, canvas);
}
frameReady = false;
requestAnimationFrame(render);
}
render();
setInterval(renderStatus, 200);
})();
}
function createCanvas(width, height, title)
{
const canvas = document.createElement('canvas');
canvas.width = width;
canvas.height = height;
canvas.title = title;
if(!document.body.contains(canvas))
document.body.appendChild(canvas);
return canvas;
}
function renderStatus()
{
const status = document.getElementById('status');
status.innerText = `FPS: ${Speedy.fps}`;
}
function draw(media, canvas, x = 0, y = 0, width = media.width, height = media.height)
{
const ctx = canvas.getContext('2d');
ctx.drawImage(media.source, x, y, width, height);
}
</script>
<mark>Powered by <a href="https://github.com/alemart/speedy-vision">speedy-vision.js</a></mark>
</body>
</html>