var _debug = document.getElementById('debug');
function debug() { _debug.textContent = [].join.call(arguments, '\n'); }

var c = document.getElementById('draw'),
	ctx = c.getContext('2d');

function onResize() {
	c.width = c.clientWidth;
	c.height = c.clientHeight;
}
window.addEventListener('resize', onResize);
onResize();

// Utils
function clip(n, m, M) { return n < M ? n > m ? n : m : M; }
function comeCloser(n, goal, factor, limit) {
	return (limit && Math.abs(goal - n) < limit) ? goal : n + (goal - n) / (factor || 10);
}
function dist(a, b) {
	var dx = b[0] - a[0], dy = b[1] - a[1], dz = b[2] - a[2];
	return Math.sqrt(dx*dx + dy*dy + dz*dz);
}
function normalize(v) {
	var l = Math.sqrt(v[0]*v[0]+v[1]*v[1]+v[2]*v[2]);
	return [v[0] / l, v[1] / l, v[2] / l];
}
function projection(p, d, s) {
	var f = (s || 1) / (1 - p[2] / d);
	return [p[0]*f, p[1]*f, p[2]];
}
function rotateX(p, a) {
	var d = Math.sqrt(p[2] * p[2] + p[1] * p[1]),
		na = Math.atan2(p[2], p[1]) + a;
	return [p[0], d * Math.cos(na), d * Math.sin(na)];
}
function rotateY(p, a) {
	var d = Math.sqrt(p[2] * p[2] + p[0] * p[0]),
		na = Math.atan2(p[0], p[2]) + a;
	return [d * Math.sin(na), p[1], d * Math.cos(na)];
}
function rotateZ(p, a) {
	var d = Math.sqrt(p[1] * p[1] + p[0] * p[0]),
		na = Math.atan2(p[1], p[0]) + a;
	return [d * Math.cos(na), d * Math.sin(na), p[2]];
}
function rotateMatrix(p, m) {
	return [
		p[0] * m[0] + p[1] * m[3] + p[2] * m[6],
		p[0] * m[1] + p[1] * m[4] + p[2] * m[7],
		p[0] * m[2] + p[1] * m[5] + p[2] * m[8]
	];
}
// Not used there but could be useful ! (gives the invert rotation)
function transpose33(m) {
	return [
		m[0], m[3], m[6],
		m[1], m[4], m[7],
		m[2], m[5], m[8]
	];
}
function rotate3dMatrix(x, y, z, a) {
	var c = 1 - Math.cos(a), s = Math.sin(a);
	return [
		1+c*(x*x-1), x*y*c+z*s, x*z*c-y*s,
		x*y*c-z*s, 1+c*(y*y-1), y*z*c+x*s,
		x*z*c+y*s, y*z*c-x*s, 1+c*(z*z-1)
	];
}
function mul33(m, n) {
	var m1 = m[0], m2 = m[1], m3 = m[2],
		m4 = m[3], m5 = m[4], m6 = m[5],
		m7 = m[6], m8 = m[7], m9 = m[8];
	
	var n1 = n[0], n2 = n[1], n3 = n[2],
		n4 = n[3], n5 = n[4], n6 = n[5],
		n7 = n[6], n8 = n[7], n9 = n[8];
	
	return [
		m1*n1+m4*n2+m7*n3, m2*n1+m5*n2+m8*n3, m3*n1+m6*n2+m9*n3,
		m1*n4+m4*n5+m7*n6, m2*n4+m5*n5+m8*n6, m3*n4+m6*n5+m9*n6,
		m1*n7+m4*n8+m7*n9, m2*n7+m5*n8+m8*n9, m3*n7+m6*n8+m9*n9
	];
}
function chainMul33(base) {
	for(var i = 1, l = arguments.length; i < l; i++)
		base = mul33(base, arguments[i]);
	return base;
}
function dot(a, b) {
	return a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
}
function cross(a, b) {
	return [
		a[1] * b[2] - a[2] * b[1],
		a[2] * b[0] - a[0] * b[2],
		a[0] * b[1] - a[1] * b[0]
	];
}
function sub(a, b) {
	return [a[0] - b[0], a[1] - b[1], a[2] - b[2]];
}

// Big chunk of code incoming !
// These are the drawing functions
// You should probably fold these functions and only open one at a time
var drawElectricity = (function() {
	// var color = 'hsl('+(Math.random() * 360)+', 60%, 50%)';
	var color = 'rgb(40,130,240)';
	var rays = [];
	for(var i = 0; i < 5; i++) {
		var dest = [Math.random() - .5, Math.random() - .5, Math.random() - .5];
		var d = Math.sqrt(dest[0] * dest[0] + dest[1] * dest[1] + dest[2] * dest[2]);
		dest[0] /= d; dest[1] /= d; dest[2] /= d;
		var parts = [], pCount = ~~(3 * Math.random()) + 3;
		for(var j = 0; j < pCount; j++) {
			parts.push({
				pos: (j + 1) / (pCount + 1),
				off: [0,0,0],
				maxOff: 4 + 3 * Math.random(),
				speed: 240
			});
		}
		var vel = 3;
		var ray = {
			dest: dest,
			vel: [vel * (Math.random() - .5), vel * (Math.random() - .5), vel * (Math.random() - .5)],
			parts: parts
		};
		rays.push(ray);
	}
	var tmpC = [document.createElement('canvas'), document.createElement('canvas')],
		tCtx = [tmpC[0].getContext('2d'), tmpC[1].getContext('2d')];
	tmpC[0].width = tmpC[0].height = tmpC[1].width = tmpC[1].height = 200;
	tCtx[0].translate(100,100); tCtx[1].translate(100,100);
	var currentCanvas = 0;
	var counter = 0, pT;
	return function(ctx, faces, allCorners) {
		var now = Date.now(), dt = 0;
		if(pT) dt = (now - pT) * .001;
		pT = now;
		var c = ctx.canvas;
		var rad = cubeSize * (.2 + .02 * Math.sin((counter += dt) * 2));
		var mx = c.width * .5, my = c.height * .5;
		ctx.strokeStyle = color;
		ctx.beginPath();
		ctx.arc(0, 0, rad, 0, 2 * Math.PI);
		var i, l, j, l2;
		for(i = 0, l = allCorners.length; i < l; i++) {
			var corner = allCorners[i];
			var dx = corner[0] - mx, dy = corner[1] - my;
			var d = Math.sqrt(dx * dx + dy * dy);
			if(d <= rad) continue;
			ctx.moveTo(rad * dx / d, rad * dy / d);
			ctx.lineTo(dx, dy);
		}
		ctx.stroke();
		currentCanvas = 1 - currentCanvas;
		var cc = tmpC[currentCanvas], cCtx = tCtx[currentCanvas];
		cCtx.clearRect(-cc.width * .5, -cc.height * .5, cc.width, cc.height);
		cCtx.shadowColor = 'transparent';
		cCtx.shadowBlur = 0;
		cCtx.globalAlpha = Math.pow(.001, dt);
		cCtx.drawImage(tmpC[1 - currentCanvas], -cc.width * .5, -cc.height * .5);
		cCtx.globalAlpha = 1;
		cCtx.strokeStyle = 'rgba(245,250,255,1)';
		cCtx.shadowColor = 'rgba(255,255,255,.5)';
		cCtx.shadowBlur = 4;
		for(i = 0, l = rays.length; i < l; i++) {
			var ray = rays[i], vel = ray.vel;
			var dest = ray.dest = rotateX(rotateY(rotateZ(ray.dest, vel[2] * dt), vel[1] * dt), vel[0] * dt);
			var previous = [0,0];
			// cCtx.beginPath();
			// cCtx.moveTo(0,0);
			for(j = 0, l2 = ray.parts.length; j < l2; j++) {
				var part = ray.parts[j], off = part.off;
				off[0] += part.speed * (Math.random() - .5) * dt;
				off[1] += part.speed * (Math.random() - .5) * dt;
				off[2] += part.speed * (Math.random() - .5) * dt;
				var d = Math.sqrt(off[0] * off[0] + off[1] * off[1] + off[2] * off[2]);
				if(d > part.maxOff) {
					var m = part.maxOff / d;
					off[0] *= m; off[1] *= m; off[2] *= m;
				}
				var pos = [part.pos * rad * dest[0] + off[0], part.pos * rad * dest[1] + off[1]];
				cCtx.lineWidth = .1 + .8 * (1 - part.pos);
				cCtx.beginPath();
				cCtx.moveTo(previous[0], previous[1]);
				cCtx.lineTo(pos[0], pos[1]);
				cCtx.stroke();
				previous = pos;
			}
			cCtx.lineWidth = .15;
			cCtx.beginPath();
			cCtx.moveTo(previous[0], previous[1]);
			cCtx.lineTo(rad * dest[0], rad * dest[1]);
			cCtx.stroke();
		}
		ctx.drawImage(cc, -cc.width * .5, -cc.height * .5);
	};
})();
var drawStars = (function() {
	var stars = [], focale = 100;
	var maxDist = 1000, f = .5 * maxDist / focale;
	var newStar = function(dist, c, bop) {
		var speed = 400 + Math.random() * 200;
		return [(Math.random() - .5) * f, (Math.random() - .5) * f, dist, speed, bop || 0];
	};
	for(var i = 0; i < 200; i++) {
		var dist = maxDist * Math.random() + 1;
		stars.push(newStar(dist, c, 1));
	}
	var pT, dtMax = 1 / 60;
	return function(ctx) {
		var now = Date.now(), dt = 0;
		if(pT) dt = Math.min((now - pT) * .001, dtMax);
		pT = now;
		var c = ctx.canvas;
		ctx.fillStyle = 'rgba(0,0,0,.8)';
		ctx.fillRect(c.width * -.5, c.height * -.5, c.width, c.height);
		for(var i = 0, l = stars.length; i < l; i++) {
			var star = stars[i];
			star[4] += dt * .5;
			star[2] -= dt * star[3];
			if(star[2] <= 0)
				star = stars[i] = newStar(maxDist, c);
			var op = Math.min(star[4], 1);
			ctx.fillStyle = 'rgba(255,255,255,'+op+')';
			var f = focale / star[2], s = 3 * f;
			ctx.fillRect(cubeSize*star[0] * f - s*.5,cubeSize*star[1] * f - s*.5,s,s);
		}
	};
})();
var drawCubes = (function() {
	var v = [], e = [];
	v.push([-1,-1,-1]);
	v.push([-1,-1, 1]);
	v.push([ 1,-1, 1]);
	v.push([ 1,-1,-1]);
	v.push([ 1, 1,-1]);
	v.push([-1, 1,-1]);
	v.push([-1, 1, 1]);
	v.push([ 1, 1, 1]);
	var eFull = '0-1 1-2 2-3 3-0 4-5 5-6 6-7 7-4 0-5 1-6 2-7 3-4'.split(' ');
	for(var i = eFull.length, ea; i--;) e.push([+(ea=eFull[i].split('-'))[0], +ea[1]]);
	var offset = Math.PI * .25, s1 = .5 / Math.sqrt(3), s2 = s1 / Math.sqrt(3), s3 = s2 / Math.sqrt(3);
	var draws = [
		{
			color: '#2ecc71',
			transform: function(p, m) { return projection(rotateX(rotateMatrix(p, m), offset), perspective, cubeSize * s1); }
			// transform: function(p, m) { return projection(rotateMatrix(rotateX(p, offset), m), f, s1); }
		}, {
			color: '#e74c3c',
			transform: function(p, m) { return projection(rotateY(rotateMatrix(p, m), offset), perspective, cubeSize * s2); }
			// transform: function(p, m) { return projection(rotateMatrix(rotateY(p, offset), m), f, s2); }
		}, {
			color: '#f1c40f',
			transform: function(p, m) { return projection(rotateZ(rotateMatrix(p, m), offset), perspective, cubeSize * s3); }
			// transform: function(p, m) { return projection(rotateMatrix(rotateZ(p, offset), m), f, s3); }
		}
	];
	return function(ctx) {
		// var y = Math.asin(rot[6]),
		// 	x = Math.atan2(-rot[7], rot[8]),
		// 	z = Math.atan2(-rot[3], rot[0]);
		// debug(180 * x / Math.PI, 180 * y / Math.PI, 180 * z / Math.PI);
		var allLines = [], i, l, d;
		for(d = draws.length; d--;) {
			var draw = draws[d];
			var points = [];
			for(i = 0, l = v.length; i < l; i++)
				points.push(draw.transform(v[i], rotMatrix));
			for(i = e.length; i--;) {
				var edge = e[i], p1 = points[edge[0]], p2 = points[edge[1]];
				var z = (p1[2] + p2[2]) * .5;
				allLines.push([p1[0], p1[1], p2[0], p2[1], z, draw.color]);
			}
		}
		// Order by z-distance to get a better look
		// (inverse because the next loop is decrementing)
		allLines.sort(function(a, b) { return b[4] - a[4]; });
		ctx.lineWidth = 1.2;
		// ctx.globalCompositeOperation = 'lighter';
		for(i = allLines.length; i--;) {
			l = allLines[i];
			ctx.strokeStyle = l[5];
			ctx.beginPath();
			ctx.moveTo(l[0], l[1]);
			ctx.lineTo(l[2], l[3]);
			ctx.stroke();
		}
	};
})();
var drawPhysics = (function() {
	// Using array for better perfs
	// 0: x, 1: y, 2: z, 3: px, 4: py, 5: pz
	function Point(x, y, z) { return [x, y, z, x, y, z]; }
	function Stick(a, b, l, style) { return [a, b, l, style]; }
	var points = [], sticks = [], objects = [];
	var tr = [0,0,0], defStyle = 'white';
	var sticksCache = {}; // Used to remove duplicates
	function setTranslation(x, y, z) { tr = [x, y, z]; }
	function addPoint(x, y, z) {
		return points.push(Point(tr[0]+x, tr[1]+y, tr[2]+z)) - 1;
	}
	function addStick(a, b, style, length) {
		var id = Math.min(a,b) + '|' + Math.max(a,b);
		if(sticksCache.hasOwnProperty(id))
			return sticksCache[id];
		if(length === undefined) length = dist(points[a], points[b]);
		return (sticksCache[id] = sticks.push(Stick(a, b, length, style === undefined ? defStyle : style)) - 1);
	}
	function addTriangle(a, b, c, h, style) {
		// h = 0;
		style = style || defStyle;
		addStick(a, b, !(h & 0x100) && style);
		addStick(b, c, !(h & 0x010) && style);
		addStick(c, a, !(h & 0x001) && style);
		return [a, b, c];
	}
	function addBox(s, x, y, z, style, parent) {
		if(style) defStyle = style;
		setTranslation(x,y,z);
		var p1 = addPoint(-s, -s, -s),
			p2 = addPoint(-s, -s,  s),
			p3 = addPoint( s, -s,  s),
			p4 = addPoint( s, -s, -s),
			p5 = addPoint(-s,  s, -s),
			p6 = addPoint(-s,  s,  s),
			p7 = addPoint( s,  s,  s),
			p8 = addPoint( s,  s, -s);
		var object = [parent, [p1,p2,p3,p4,p5,p6,p7,p8]];
		// clockwise points
		object.push(addTriangle(p1, p3, p2, 0x100));
		object.push(addTriangle(p1, p4, p3));
		object.push(addTriangle(p1, p6, p5, 0x100));
		object.push(addTriangle(p1, p2, p6));
		object.push(addTriangle(p1, p5, p4, 0x010));
		object.push(addTriangle(p4, p5, p8));
		object.push(addTriangle(p2, p7, p6, 0x100));
		object.push(addTriangle(p2, p3, p7));
		object.push(addTriangle(p3, p4, p8, 0x001));
		object.push(addTriangle(p3, p8, p7));
		object.push(addTriangle(p5, p6, p7, 0x001));
		object.push(addTriangle(p5, p7, p8));
		
		// Reinforce by adding sticks (could also add every face other diagonal)
		addStick(p1, p7, null);
		addStick(p2, p8, null);
		addStick(p3, p5, null);
		addStick(p4, p6, null);
		
		// Init spin
		// p1[3] += (Math.random()-.5)*.3;
		// p1[4] += (Math.random()-.5)*.3;
		// p1[5] += (Math.random()-.5)*.3;
		
		return objects.push(object) - 1;
	}
	function addTetrahedron(s, x, y, z, style, parent) {
		if(style) defStyle = style;
		setTranslation(x,y,z);
		var t = s;
		s *= Math.SQRT2;
		var p1 = addPoint( s,  0, -t),
			p2 = addPoint(-s,  0, -t),
			p3 = addPoint( 0, -s,  t),
			p4 = addPoint( 0,  s,  t);
		var object = [parent, [p1,p2,p3,p4]];
		// clockwise points
		object.push(addTriangle(p1, p2, p4));
		object.push(addTriangle(p1, p4, p3));
		object.push(addTriangle(p1, p3, p2));
		object.push(addTriangle(p2, p3, p4));
		
		return objects.push(object) - 1;
	}
	addBox(.50, 0, 0, 0, '#e74c3c');
	addBox(.25, 0, 0, 0, '#2ecc71', 0);
	addTetrahedron(.125, 0, 0, 0, '#f1c40f', 1);
	
	var accuracy = 3;
	var stiffness = 1, bounce = 0; // Adjust accordingly with accuracy
	var friction = .98, gravity = .003;
	var fBases = [[1,0,0], [-1,0,0], [0,1,0], [0,-1,0], [0,0,1], [0,0,-1]];
	var fs = [];
	var proj = [], lines = [];
	var paused = false; // [1,0,0,0,1,0,0,0,1]
	// document.addEventListener('mousedown', (e) => e.which === 3 && (paused = paused ? false : transpose33(rotMatrix)));
	// document.addEventListener('contextmenu', (e) => e.preventDefault());
	function applyVel() {
		for(var i = points.length; i--;) {
			var p = points[i];
			var vx = (p[0] - p[3]) * friction,
				vy = (p[1] - p[4]) * friction,
				vz = (p[2] - p[5]) * friction;
			var gVec = [0, gravity, 0];
			// var gVec = rotateMatrix([0, gravity, 0], transpose33(rotMatrix));
			p[3] = p[0]; p[4] = p[1]; p[5] = p[2];
			p[0] += vx + gVec[0];
			p[1] += vy + gVec[1];
			p[2] += vz + gVec[2];
		}
	}
	var ns = [];
	function constraints() {
		ns = [];
		// bounds (external cube)
		for(var i = points.length; i--;) {
			var p = points[i];
			for(var j = fs.length; j--;) {
				var f = fs[j];
				var d = dot(p, f) - 1;
				if(d > 0) { // Outside !
					for(var j = 0; j < 3; j++) {
						p[j+3] += bounce * d * f[j];
						p[j] -= d * f[j];
					}
				}
			}
		}
		// Objects inside objects
		for(var i = 0, l = objects.length; i < l; i++) {
			var o = objects[i], op = o[1];
			if(typeof o[0] === 'number') {
				var p = objects[o[0]];
				for(var j = p.length; j-->2;) {
					var tri = p[j];
					var p1 = tri[0], p2 = tri[1], p3 = tri[2];
					var a = points[p1], b = points[p2], c = points[p3];
					var n = normalize(cross(sub(b, a), sub(c, a)));
					for(var k = op.length; k--;) {
						var pt = points[op[k]];
						var d = dot(sub(pt, a), n);
						if(d > 0) {
							for(var coord = 0; coord < 3; coord++) {
								var q = d * n[coord], qb = bounce * q;
								pt[coord+3] += qb;
								pt[coord] -= q;
							}
						}
					}
				}
			}
		}
		// sticks lengths
		for(var i = sticks.length; i--;) {
			var s = sticks[i], p0 = points[s[0]], p1 = points[s[1]];
			var dx = p1[0] - p0[0], dy = p1[1] - p0[1], dz = p1[2] - p0[2];
			var d = Math.sqrt(dx*dx + dy*dy + dz*dz);
			var dd = s[2] - d, p = stiffness * .5 * dd / d;
			var offX = dx * p, offY = dy * p, offZ = dz * p;
			p0[0] -= offX; p0[1] -= offY; p0[2] -= offZ;
			p1[0] += offX; p1[1] += offY; p1[2] += offZ;
		}
	}
	function update() {
		if(!paused) {
			fs = [];
			for(var i = fBases.length; i--;)
				fs.push(rotateMatrix(fBases[i], rotMatrix));
			applyVel();
			for(var i = accuracy; i--;)
				constraints();
		}
		proj = []; lines = [];
		for(var i = 0, l = points.length; i<l; i++)
			proj.push(projection(!paused ? points[i] : rotateMatrix(rotateMatrix(points[i], paused), rotMatrix), perspective));
		for(var i = sticks.length; i--;) {
			var s = sticks[i];
			if(!s[3]) continue;
			var a = proj[s[0]], b = proj[s[1]];
			lines.push([a[0], a[1], b[0], b[1], s[3], (a[2] + b[2]) * .5]);
		}
		lines.sort(function(a, b) { return b[5] - a[5]; });
	}
	// Above 100fps, consider that we try to draw 2 times the same frame (so only update once)
	var pT, minFrameLength = 1000/100, time = 0;
	return function(ctx) {
		var now = Date.now(), dt = 0;
		if(pT) dt = now - pT;
		pT = now;
		time += dt;
		if(time >= minFrameLength) {
			time = 0;
			update();
		}
		// [-1; 1]
		ctx.scale(cubeSize * .5, cubeSize * .5);
		// ctx.fillStyle = 'white';
		// for(var i = points.length; i--;) {
		// 	var p = proj[i];
		// 	var size = .04 * (p[2] + 1);
		// 	ctx.fillRect(p[0] - size * .5, p[1] - size * .5, size, size);
		// }
		
		ctx.lineWidth = 2 / cubeSize;
		// ctx.strokeStyle = 'white';
		// ctx.beginPath();
		for(var i = lines.length; i--;) {
			var l = lines[i];
			ctx.strokeStyle = l[4];
			ctx.beginPath();
			ctx.moveTo(l[0], l[1]);
			ctx.lineTo(l[2], l[3]);
			ctx.stroke();
		}
		// ctx.stroke();
	};
})();
var drawPong = (function() {
	// This one is a bit ugly (quickly coded)
	// Meant to be viewed from the right
	var ballSize = .05, ballSpeed = 2.5;
	var ball = [0,0,0], ballVel = [0,0,0];
	var p1 = [0,0,1], p2 = [0,0,-1];
	var hits = [],// hitsFront = [],
		hitS = .1, hitM = 2;
	function mirrorRandNZ(m) {
		return (Math.random() + m) * (~~(Math.random() * 2) * 2 - 1);
	}
	function start() {
		var v = [mirrorRandNZ(.5), mirrorRandNZ(.5), mirrorRandNZ(.9)];
		var l = ballSpeed / Math.sqrt(v[0]*v[0] + v[1]*v[1] + v[2]*v[2]);
		ballVel = [v[0] * l, v[1] * l, v[2] * l];
	}
	function transformed(p) {
		return projection(rotateMatrix(p, rotMatrix), perspective);
	}
	function addHit(pos, dx, dy, front) {
		// (front ? hitsFront : hits).push([pos, dx, dy, 0]);
		hits.push([pos, dx, dy, 0]);
	}
	function clipV(v) {
		return [clip(v[0], -1, 1), clip(v[1], -1, 1), clip(v[2], -1, 1)];
	}
	function hitSq(ctx, center, size, dx, dy) {
		var p1 = clipV([center[0] + size * (-dx[0] - dy[0]), center[1] + size * (-dx[1] - dy[1]), center[2] + size * (-dx[2] - dy[2])]),
			p2 = clipV([center[0] + size * ( dx[0] - dy[0]), center[1] + size * ( dx[1] - dy[1]), center[2] + size * ( dx[2] - dy[2])]),
			p3 = clipV([center[0] + size * ( dx[0] + dy[0]), center[1] + size * ( dx[1] + dy[1]), center[2] + size * ( dx[2] + dy[2])]),
			p4 = clipV([center[0] + size * (-dx[0] + dy[0]), center[1] + size * (-dx[1] + dy[1]), center[2] + size * (-dx[2] + dy[2])]);
		p1 = transformed(p1); p2 = transformed(p2); p3 = transformed(p3); p4 = transformed(p4);
		ctx.moveTo(p1[0], p1[1]);
		ctx.lineTo(p2[0], p2[1]);
		ctx.lineTo(p3[0], p3[1]);
		ctx.lineTo(p4[0], p4[1]);
		ctx.lineTo(p1[0], p1[1]);
	}
	function updateDrawHit(ctx, dt, hit) {
		hit[3] += dt;
		var peak = hit[3] * 4, max = 0;
		for(var x = -hitM; x <= hitM; x++)
			for(var y = -hitM; y <= hitM; y++) {
				var d = 1 + Math.abs(Math.sqrt(x * x + y * y) - peak);
				var op = clip(2.5 / d - 1, 0, 1);
				if(op > max) max = op;
				ctx.fillStyle = 'rgba(200,30,120,'+op+')';
				// ctx.fillRect(p[0]+(x-.5)*s,p[1]+(y-.5)*s,s,s);
				ctx.beginPath();
				var c = [hit[0][0] + hitS * ((x-.5)*hit[1][0]+(y-.5)*hit[2][0]), hit[0][1] + hitS * ((x-.5)*hit[1][1]+(y-.5)*hit[2][1]), hit[0][2] + hitS * ((x-.5)*hit[1][2]+(y-.5)*hit[2][2])];
				hitSq(ctx, c, hitS * .5, hit[1], hit[2]);
				ctx.fill();
			}
		return max >= .01;
	}
	start();
	var pT, dtMax = 1 / 60;
	return function(ctx) {
		var now = Date.now(), dt = 0;
		if(pT) dt = Math.min((now - pT) * .001, dtMax);
		pT = now;
		ctx.scale(cubeSize * .5, cubeSize * .5);
		
		ball[0] += ballVel[0] * dt;
		ball[1] += ballVel[1] * dt;
		ball[2] += ballVel[2] * dt;
		if(ball[0] < ballSize - 1) {
			ball[0] = ballSize - 1;
			ballVel[0] *= -1;
			addHit([-1, ball[1], ball[2]], [0,0,1], [0,1,0]);
		}
		if(ball[0] > 1 - ballSize) {
			ball[0] = 1 - ballSize;
			ballVel[0] *= -1;
			// addHit([1, ball[1], ball[2]], [0,0,1], [0,1,0], true);
		}
		if(ball[1] < ballSize - 1) {
			ball[1] = ballSize - 1;
			ballVel[1] *= -1;
			addHit([ball[0], -1, ball[2]], [1,0,0], [0,0,1]);
		}
		if(ball[1] > 1 - ballSize) {
			ball[1] = 1 - ballSize;
			ballVel[1] *= -1;
			addHit([ball[0], 1, ball[2]], [1,0,0], [0,0,1]);
		}
		if(ball[2] < ballSize - 1) {
			ball[2] = ballSize - 1;
			ballVel[2] *= -1;
			// addHit([ball[0], ball[1], -1], [1,0,0], [0,1,0]);
		}
		if(ball[2] > 1 - ballSize) {
			ball[2] = 1 - ballSize;
			ballVel[2] *= -1;
			// addHit([ball[0], ball[1], 1], [1,0,0], [0,1,0]);
		}
		// Should only call these once per frame
		// (or find a way to use dt with it)
		p1[0] = comeCloser(p1[0], ball[0], 2 + 20 * (1 - ball[2]));
		p1[1] = comeCloser(p1[1], ball[1], 2 + 20 * (1 - ball[2]));
		p2[0] = comeCloser(p2[0], ball[0], 2 + 20 * (ball[2] + 1));
		p2[1] = comeCloser(p2[1], ball[1], 2 + 20 * (ball[2] + 1));
		ctx.fillStyle = 'white';
		ctx.beginPath();
		hitSq(ctx, p1, .2, [1,0,0], [0,1,0]);
		hitSq(ctx, p2, .2, [1,0,0], [0,1,0]);
		ctx.fill();
		hits = hits.filter(updateDrawHit.bind(this, ctx, dt));
		
		var bPos = transformed(ball);
		var s = ballSize / (1 - bPos[2] / perspective);
		ctx.fillStyle = 'white';
		ctx.beginPath();
		ctx.arc(bPos[0], bPos[1], s, 0, 2 * Math.PI);
		ctx.fill();
		
		// hitsFront = hitsFront.filter(updateDrawHit.bind(this, ctx, dt));
	};
})();
var drawGrowing = (function() {
	function easing(t) {
		return t<.5 ? 2*t*t : (t-1)*(2*t-2)*(2*t-2)+1;
	}
	var globalScale = 1, globalRot = 0, rotX = -.17;
	function transformed(v) { return projection(rotateX(rotateY(v, globalRot), rotX), perspective); }
	function box(ctx, sX, sY, sZ) {
		var p1 = transformed([-sX, -sY, sZ]),
			p2 = transformed([ sX, -sY, sZ]),
			p3 = transformed([ sX,  sY, sZ]),
			p4 = transformed([-sX,  sY, sZ]),
			p5 = transformed([-sX, -sY,-sZ]),
			p6 = transformed([ sX, -sY,-sZ]),
			p7 = transformed([ sX,  sY,-sZ]),
			p8 = transformed([-sX,  sY,-sZ]);
		ctx.moveTo(p1[0], p1[1]);
		ctx.lineTo(p2[0], p2[1]);
		ctx.lineTo(p3[0], p3[1]);
		ctx.lineTo(p4[0], p4[1]);
		ctx.lineTo(p1[0], p1[1]);
		ctx.lineTo(p5[0], p5[1]);
		ctx.lineTo(p6[0], p6[1]);
		ctx.lineTo(p7[0], p7[1]);
		ctx.lineTo(p8[0], p8[1]);
		ctx.lineTo(p5[0], p5[1]);
		ctx.moveTo(p2[0], p2[1]);
		ctx.lineTo(p6[0], p6[1]);
		ctx.moveTo(p3[0], p3[1]);
		ctx.lineTo(p7[0], p7[1]);
		ctx.moveTo(p4[0], p4[1]);
		ctx.lineTo(p8[0], p8[1]);
	}
	var pT, dtMax = 1 / 60, t = 0;
	var animDur = 2.1;
	return function(ctx) {
		var now = Date.now(), dt = 0;
		if(pT) dt = Math.min((now - pT) * .001, dtMax);
		pT = now;
		t += dt;
		var p = (t % animDur) / animDur;
		globalScale = 1 - p * .5;
		globalRot = p * Math.PI / 2;
		var sc = cubeSize * .2;
		ctx.scale(sc, sc);
		ctx.strokeStyle = '#57ff57';
		ctx.lineWidth = .75 / sc;
		ctx.beginPath();
		box(ctx, globalScale, globalScale, globalScale);
		var scx = easing(clip(p / .27, 0, 1)) * 1.5 + .5,
			scy = easing(clip((p - .27) / .27, 0, 1)) * 1.5 + .5,
			scz = easing(clip((p - .54) / .27, 0, 1)) * 1.5 + .5;
		box(ctx, globalScale * scx, globalScale * scy, globalScale * scz);
		ctx.stroke();
	};
})();

// Now the cube logic
var baseCorners = [
	[-1, -1,  1], [ 1, -1,  1], [ 1, 1,  1], [-1, 1,  1],
	[ 1, -1, -1], [-1, -1, -1], [-1, 1, -1], [ 1, 1, -1],
];
// Here are the faces of the cube
// You can use the same draw for multiple faces !
// But be careful, the function will be called for every face
// So if you increment something it will be incremented multiple times per frame
// Name is not actually used here except for human-readability (but could be used in a drawing function)
var faces = [
	{
		name: 'front',
		corners: [0,1,2,3],
		draw: drawElectricity
	}, {
		name: 'back',
		corners: [4,5,6,7],
		draw: drawGrowing
		// ... empty ?
		// draw: function() { return true; }
		// draw: function(ctx) { var c = ctx.canvas; ctx.clearRect(-c.width*.5, -c.height*.5, c.width, c.height); }
	}, {
		name: 'right',
		corners: [1,4,7,2],
		draw: drawPong
	}, {
		name: 'left',
		corners: [5,0,3,6],
		draw: drawStars
	}, {
		name: 'bottom',
		corners: [3,2,7,6],
		draw: drawPhysics
	}, {
		name: 'top',
		corners: [5,4,1,0],
		draw: drawCubes
	}];

// Style things
var faceBg = 'rgba(4,13,24,.65)',
	border = 'rgb(40,130,240)';
var cubeSize = 160, perspective = 15;

// Change rot to change the initial rotation (radians)
// rotVel is the angular velocity in rad/sec around every axis
var rot = [0,0,0], rotVel = [-6e-3,7.6e-3,2.13e-3],
	rotBase = [1,0,0,0,1,0,0,0,1], rotMatrix;
// Used mainly when dragging
function setBase() {
	rotBase = rotMatrix;
	rot = [0,0,0];
}
var autoRot = document.getElementById('autoRotate');
autoRot.addEventListener('change', setBase);

// Actual drawing loop
function loop() {
	if(autoRot.checked) {
		rot[0] += rotVel[0];
		rot[1] += rotVel[1];
		rot[2] += rotVel[2];
	}
	// Compute the current rotation matrix
	var mx = rotate3dMatrix(1,0,0,rot[0]),
		my = rotate3dMatrix(0,1,0,rot[1]),
		mz = rotate3dMatrix(0,0,1,rot[2]);
	rotMatrix = chainMul33(mx, my, mz, rotBase);
	
	var w = c.width, h = c.height;
	var corners = baseCorners.map(function(c) {
		var res = projection(rotateMatrix(c, rotMatrix), perspective, cubeSize * .5);
		res[0] += w * .5; res[1] += h * .5;
		return res;
	});
	ctx.clearRect(0, 0, w, h);
	// Compute every face corners position and its z position
	for(var i = 0, l = faces.length; i < l; i++) {
		var face = faces[i];
		var z = 0;
		var faceCorners = face.currentCorners = face.corners.map(function(i) { var c = corners[i]; z+=c[2]; return c; });
		face.z = z*.25;
	}
	// Sort by z to draw what is behind first
	faces.sort(function(a, b) { return a.z - b.z; });
	for(var i = 0, l = faces.length; i < l; i++) {
		var face = faces[i];
		var faceCorners = face.currentCorners;
		ctx.save();
		// Clip twice : the first time to remove the face when it's not facing us
		// The second time to actually only draw on the face
		ctx.beginPath();
		ctx.rect(0, 0, c.width, c.height);
		drawPath(ctx, faceCorners);
		ctx.clip();
		ctx.beginPath();
		drawPath(ctx, faceCorners);
		ctx.clip();
		var drawBg;
		if(face.draw) {
			ctx.save();
			ctx.translate(w * .5, h * .5);
			drawBg = face.draw(ctx, faces, corners);
			ctx.restore();
		}
		// if(drawBg === undefined) drawBg = true;
		ctx.restore();
		
		ctx.fillStyle = faceBg;
		ctx.strokeStyle = border;
		ctx.lineWidth = .5;
		
		// Always draw the background if facing back
		ctx.save();
		ctx.beginPath();
		ctx.rect(c.width, 0, -c.width, c.height);
		drawPath(ctx, faceCorners);
		ctx.clip();
		ctx.beginPath();
		drawPath(ctx, faceCorners);
		ctx.fill();
		ctx.restore();
		
		ctx.beginPath();
		drawPath(ctx, faceCorners);
		if(drawBg) ctx.fill();
		ctx.stroke();
	}
	requestAnimationFrame(loop);
}
requestAnimationFrame(loop);

function drawPath(ctx, corners) {
	if(!corners.length) return;
	ctx.moveTo(corners[0][0], corners[0][1]);
	for(var i = 0, l = corners.length; i < l; i++)
		ctx.lineTo(corners[i][0], corners[i][1]);
	ctx.lineTo(corners[0][0], corners[0][1]);
}

// Handle mouse/touch events
(function() {
	var grabbed = false, moved = false, cPos, pPos;
	var lastMoveTime, vel, timer;
	var factor = 3e-3;
	function getPos(e) {
		if(e.touches && e.touches.length)
			e = e.touches[0];
		return [e.clientX,e.clientY];
	}
	function stopMomentum() { cancelAnimationFrame(timer); timer = null; }
	function mouseDown(e) {
		if(grabbed) return;
		// if(!e.touches)
		// 	e.preventDefault();
		stopMomentum();
		cPos = pPos = grabbed = getPos(e);
		moved = false;
	}
	function mouseMove(e) {
		if(!grabbed) return;
		var pos = getPos(e);
		var dx = grabbed[1] - pos[1], dy = pos[0] - grabbed[0];
		if(!moved) {
			if(dx * dx + dy * dy < 16) return;
			moved = true;
			autoRot.checked = false;
			// rotBase = getRotMatrix(getComputedStyle(cube).getPropertyValue('transform'));
			// rot = [0,0,0];
			setBase();
		}
		lastMoveTime = Date.now();
		pPos = cPos; cPos = pos;
		rot = [dx * factor, dy * factor, 0];
	}
	function mouseUp(e) {
		if(!grabbed) return;
		grabbed = false;
		if(!moved) return;
		var f = Math.max(0, 1 - (Date.now() - lastMoveTime) / 200);
		vel = [(pPos[1] - cPos[1]) * factor * f, (cPos[0] - pPos[0]) * factor * f];
		timer = requestAnimationFrame(momentum);
	}
	function momentum() {
		if(Math.abs(vel[0]) < .001 && Math.abs(vel[1]) < .001)
			return;
		var decay = .97;
		vel[0] *= decay; vel[1] *= decay;
		rot[0] += vel[0]; rot[1] += vel[1];
		if(timer)
			timer = requestAnimationFrame(momentum);
	}
	document.addEventListener('mousedown', mouseDown);
	document.addEventListener('mousemove', mouseMove);
	document.addEventListener('mouseup', mouseUp);
	document.addEventListener('click', function(e) { if(!moved) return; e.preventDefault(); e.stopPropagation(); }, true);
	document.addEventListener('touchstart', mouseDown);
	document.addEventListener('touchmove', mouseMove);
	document.addEventListener('touchend', mouseUp);
})();