Published
Edited
May 28, 2018
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canvas.canvas
circle = function circle
(context, x, y, radius) {
var c = context;
c.beginPath();
c.arc(x, y, radius, 0, Math.PI*2, true);
c.closePath();
}
regularPolygon = function regularPolygon
(context, x, y, radius, angle, sides) {
var c = context;
var innerAngle = (2.0 * Math.PI) / sides;
c.save();
c.beginPath();
c.translate(x, y);
c.rotate(angle);
c.scale(radius, radius);
c.moveTo(1,0);
for (var i=0; i < sides; i++) {
c.rotate(innerAngle);
c.lineTo(1,0);
};
c.closePath();
c.restore();
}
regularQuadraticStar = function regularQuadraticStar
(context, x, y, radius, angle, sides) {
var c = context;
var innerAngle = (2.0 * Math.PI) / sides;
c.save();
c.beginPath();
c.translate(x, y);
c.rotate(angle);
c.scale(radius, radius);
c.moveTo(1,0);
for (var i=0; i < sides; i++) {
c.rotate(innerAngle);
c.quadraticCurveTo(0, 0, 1, 0);
};
c.closePath();
c.restore();
}
regularStar = function regularStar
(context, x, y, radius, angle, sides, pointiness) {
var c = context;
var halfInnerAngle = (Math.PI) / sides
c.save();
c.beginPath();
c.translate(x, y);
c.rotate(angle);
c.scale(radius, radius);
c.moveTo(1,0);
for (var i=0; i < sides; i++) {
c.rotate(halfInnerAngle);
c.lineTo(1 - pointiness, 0);
c.rotate(halfInnerAngle);
c.lineTo(1,0);
};
c.closePath();
c.restore();
}
uniformRandom = function uniformRandom
(low, high) {
if (typeof(high) === 'undefined') {
high = low;
low = 0;
}
return low + (high - low) * Math.random();
}
randomInt = function randomInt
(low, high) {
return Math.floor(uniformRandom(low, high));
}
randomChoice = function randomChoice
(array) {
var choice = Math.floor(Math.random() * array.length);
return array[choice];
}
random_color = function randomColor() {
var r = randomInt(30, 256);
var g = randomInt(30, 256);
var b = randomInt(30, 256);
var a = uniformRandom(0.2, 1.0);
return 'rgba(' + r + ',' + g + ',' + b + ',' + a + ')';
}
randomShape = function randomShape
(context, width, height, maxradius) {
var c = context;
c.save()
var minradius = 0.1 * maxradius;
var minstroke = 0.5;
var maxstroke = 5.0;
var x = uniformRandom(0, width);
var y = uniformRandom(0, height);
var radius = uniformRandom(minradius, maxradius);
var angle = uniformRandom(0.0, 2.0 * Math.PI);
var sides = randomInt(3,9);
var pointiness = uniformRandom(0.3, 0.9);
var shape = randomChoice(
[circle, regularPolygon, regularQuadraticStar, regularStar]);
c.fillStyle = random_color();
c.strokeStyle = random_color();
c.lineJoin = randomChoice(['round', 'bevel', 'miter']);
c.miterLimit = 10;
c.lineWidth = uniformRandom(minstroke, maxstroke);
// actually draw the shape
shape(c, x, y, radius, angle, sides, pointiness);
c.fill();
c.stroke();
c.restore()
}
fillCanvas = function fillCanvas (context, color) {
var c = context;
c.save();
c.fillStyle = color;
c.fillRect(0, 0, c.canvas.width, c.canvas.height);
c.restore();
}
canvas = {
var canvaswidth = width;
var canvasheight = 400;
var c = DOM.context2d(canvaswidth, canvasheight);
while (true) {
fillCanvas(c, black_background ? 'rgb(0, 0, 0)' : 'rgb(255, 255, 255)')
for (var i=0; i < nshapes; i++) {
randomShape(c, canvaswidth, canvasheight, 30);
yield c;
};
// After drawing n shapes, wait 3 seconds and start over.
yield Promises.delay(3000, c)
}
}
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