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bret-victor-tree.html
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bret-victor-tree.html
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<!DOCTYPE html>
<html>
<head><title>🌸</title></head>
<body>
<canvas id="canvas" width="500" height="500"></canvas>
<script>
//
// MersenneTwister
// from https://gist.github.com/300494
//
var seed = 1
var MersenneTwister = function (seed) {
if (seed == undefined) {
seed = new Date().getTime();
}
this.N = 624;
this.M = 397;
this.MATRIX_A = 0x9908b0df; /* constant vector a */
this.UPPER_MASK = 0x80000000; /* most significant w-r bits */
this.LOWER_MASK = 0x7fffffff; /* least significant r bits */
this.mt = new Array(this.N); /* the array for the state vector */
this.mti = this.N + 1; /* mti==N+1 means mt[N] is not initialized */
this.init_genrand(seed);
}
MersenneTwister.prototype.init_genrand = function (s) {
this.mt[0] = s >>> 0;
for (this.mti = 1; this.mti < this.N; this.mti++) {
var s = this.mt[this.mti - 1] ^ (this.mt[this.mti - 1] >>> 30);
this.mt[this.mti] = (((((s & 0xffff0000) >>> 16) * 1812433253) << 16) + (s & 0x0000ffff) * 1812433253)
+ this.mti;
this.mt[this.mti] >>>= 0;
}
}
MersenneTwister.prototype.genrand_int32 = function () {
var y;
var mag01 = new Array(0x0, this.MATRIX_A);
/* mag01[x] = x * MATRIX_A for x=0,1 */
if (this.mti >= this.N) { /* generate N words at one time */
var kk;
if (this.mti == this.N + 1) /* if init_genrand() has not been called, */
this.init_genrand(5489); /* a default initial seed is used */
for (kk = 0; kk < this.N - this.M; kk++) {
y = (this.mt[kk] & this.UPPER_MASK) | (this.mt[kk + 1] & this.LOWER_MASK);
this.mt[kk] = this.mt[kk + this.M] ^ (y >>> 1) ^ mag01[y & 0x1];
}
for (; kk < this.N - 1; kk++) {
y = (this.mt[kk] & this.UPPER_MASK) | (this.mt[kk + 1] & this.LOWER_MASK);
this.mt[kk] = this.mt[kk + (this.M - this.N)] ^ (y >>> 1) ^ mag01[y & 0x1];
}
y = (this.mt[this.N - 1] & this.UPPER_MASK) | (this.mt[0] & this.LOWER_MASK);
this.mt[this.N - 1] = this.mt[this.M - 1] ^ (y >>> 1) ^ mag01[y & 0x1];
this.mti = 0;
}
y = this.mt[this.mti++];
y ^= (y >>> 11);
y ^= (y << 7) & 0x9d2c5680;
y ^= (y << 15) & 0xefc60000;
y ^= (y >>> 18);
return y >>> 0;
}
MersenneTwister.prototype.random = function () {
return this.genrand_int32() * (1.0 / 4294967295.0);
}
//
// Global functions used in tree.js
//
function resetRandom() {
mt = new MersenneTwister(seed);
}
function tween(i, a, b, c, d) { //1, 62, 12, 3
return (c - i) / c * b * (i / d)
}
function random(lower, upper) {
return lower + mt.random() * (upper - lower);
}
function lerp(low, high, percent) {
return low + (high - low) * percent;
}
function extendCanvasContext(ctx) {
ctx.fillCircle = function (x, y, radius) {
ctx.beginPath();
ctx.arc(x, y, radius, 0, 2 * Math.PI, true);
ctx.fill();
ctx.closePath();
}
}
//========================================
//
// scene
//
var ctx, canvasWidth, canvasHeight;
function drawScene(canvas) {
ctx = canvas.getContext("2d");
extendCanvasContext(ctx);
canvasWidth = parseInt(canvas.getAttribute("width"));
canvasHeight = parseInt(canvas.getAttribute("height"));
drawSky();
drawMountains();
drawTree();
}
//---------------------------------------
//
// sky
//
function drawSky() {
ctx.save();
var gradient = ctx.createLinearGradient(0, 0, 0, canvasHeight);
gradient.addColorStop(0, "#b4e0fe");
gradient.addColorStop(1, "#d3f8ff");
ctx.fillStyle = gradient;
ctx.fillRect(0, 0, canvasWidth, canvasHeight);
ctx.restore();
}
//---------------------------------------
//
// mountains
//
function drawMountains() {
resetRandom();
drawMountain(130, "#8bb2bb");
drawMountain(50, "#618087");
}
function drawMountain(offset, fillStyle) {
var x = 0;
var y = canvasHeight - offset;
ctx.beginPath();
ctx.moveTo(x, y);
while (x >= 0 && x < canvasWidth) {
x += random(2, 10);
y += random(-4, 3);
ctx.lineTo(x, y);
}
ctx.lineTo(canvasWidth, canvasHeight);
ctx.lineTo(0, canvasHeight);
ctx.closePath();
ctx.fillStyle = fillStyle;
ctx.fill();
}
//---------------------------------------
//
// tree
//
function drawTree() {
var blossomPoints = [];
resetRandom();
drawBranches(0, -Math.PI / 2, canvasWidth / 2, canvasHeight, 30, blossomPoints);
resetRandom();
drawBlossoms(blossomPoints);
}
function drawBranches(i, angle, x, y, width, blossomPoints) {
ctx.save();
var length = tween(i, 1, 62, 12, 3) * random(0.7, 1.3);
if (i == 0) { length = 98; }
ctx.translate(x, y);
ctx.rotate(angle);
ctx.fillStyle = "#000";
ctx.fillRect(0, -width / 2, length, width);
ctx.restore();
var tipX = Math.floor(x + (length - width / 2) * Math.cos(angle));
var tipY = Math.floor(y + (length - width / 2) * Math.sin(angle));
if (i > 5) {
blossomPoints.push([x, y, tipX, tipY]);
}
if (i < 6) {
drawBranches(i + 1, angle + random(-0.15, -0.05) * Math.PI/*?*/, tipX, tipY, width * .65, blossomPoints);
drawBranches(i + 1, angle + random(0.15, 0.05) * Math.PI/*?*/, tipX, tipY, width * .65, blossomPoints);
}
else if (i < 9) {
drawBranches(i + 1, angle + random(0.15, 0.05) * Math.PI/*?*/, tipX, tipY, width * .6, blossomPoints);
}
}
function drawBlossoms(blossomPoints) {
var colors = ["#f5ceea", "#e8d9e4", "#f7c9f3", "#ebb4cc", "#cccccc"];//?
ctx.globalAlpha = 0.60;
for (var i = 0; i < blossomPoints.length; i++) {
var p = blossomPoints[i];
for (var j = 0; j < 16; j++) {
var x = lerp(p[0], p[2], random(0, 1))// + random(-10,10);
var y = lerp(p[1], p[3], random(0, 1))// + random(-10,10);
ctx.fillStyle = colors[Math.floor(random(0, colors.length))];
ctx.fillCircle(x, y, 5);
}
}
ctx.globalAlpha = 1.0;
}
document.addEventListener('keydown', (e) => {
if (e.keyCode === 37) {
seed-=1;
} else {
seed+=1;
}
console.log(seed)
drawScene(document.getElementById('canvas'));
})
drawScene(document.getElementById('canvas'));
</script>
</body>
</html>