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part17e_motion_detection.html
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part17e_motion_detection.html
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<!DOCTYPE html>
<html>
<title>Creative Coding Yea!</title>
<head>
<meta charset="utf-8">
<script language="javascript" src="js/creative_coding.js"></script>
<script language="javascript" src="js/canvas.js"></script>
<script language="javascript" src="js/video.js"></script>
<script language="javascript" src="js/quicksettings.min.js"></script>
<link rel="stylesheet" href="css/reset.css" type="text/css" media="screen" />
<link rel="stylesheet" href="css/style.css" type="text/css" media="screen" />
</head>
<body>
<script>
var ctx = createCanvas("canvas1");
var ctx2 = createHiddenCanvas("canvas2");
var scalefactor = 40;
var old = [];
var threshold = 40;
var settings = QuickSettings.create();
function setup(){
video.width = w/scalefactor;
video.height = h/scalefactor;
}
settings.addRange("threshold", 5, 100, threshold, 1, function(value) {
threshold = value;
});
function draw(){
ctx2.drawImage(video, 0, 0, w, h);
var data = ctx2.getImageData(0, 0, w, h).data;
ctx.background(0, 0.05);
var motion = motionDetection();
for (var i = 0; i < motion.length; i++) {
var m = motion[i];
ctx.fillStyle = rgb(m.r, m.g, m.b);
ctx.fillEllipse(m.x, m.y, scalefactor, scalefactor);
ctx.fillStyle = rgb(0);
ctx.fillEllipse(m.x, m.y, scalefactor/2, scalefactor/2);
}
}
function motionDetection(){
var motion = [];
// draw the video and get its pixels
ctx.drawImage(video, 0, 0, video.width, video.height);
var data = ctx.getImageData(0, 0, video.width, video.height).data;
// we can now loop over all the pixels of the video
for (var y = 0; y < video.height; y++) {
for (var x = 0; x < video.width; x++) {
var pos = (x + y * video.width) * 4;
var r = data[pos];
var g = data[pos+1];
var b = data[pos+2];
if(old[pos] && Math.abs(old[pos].red - r) > threshold) {
// push the x, y and rgb values into the motion array
// but multiply the x and y values bck up by scalefactor
// to get their actual screen position
motion.push({x: x * scalefactor, y: y * scalefactor, r: r, g: g, b: b});
}
old[pos] = { red: r, green: g, blue: b};
}
}
return motion;
}
</script>
</body>
</html>