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Quellcode

var dir = {x: this.position.x, y: this.position.y};
vMath.subV(dir, objects[i].position);
var dist = vMath.length(dir);
var dir2 = {x: this.position.x, y: this.position.y};
vMath.subV(dir2, {x: objects[i].position.x + objects[i].size, y: objects[i].position.y + objects[i].size});
var dist2 = vMath.length(dir2);
// 'cast' shadow
ctx.globalCompositeOperation = "destination-out";
ctx.fillRect(objects[i].position.x, objects[i].position.y, objects[i].size, objects[i].size);
// remove corners facing from light source away
ctx.beginPath();
// todo: polygons
ctx.moveTo(objects[i].position.x, objects[i].position.y);
var p2 = new Vec2M(objects[i].position.x, objects[i].position.y);
var s1 = new Vec2M(this.position.x, this.position.y);
var p1 = s1.subV(p2);
p1.normalize();
p1 = p1.mulS(dist - this.strength - 50);
var end1 = p1.addV(p2);
ctx.lineTo(end1.x, end1.y);

ctx.moveTo(objects[i].position.x + objects[i].size, objects[i].position.y + objects[i].size);
p2 = new Vec2M(objects[i].position.x + objects[i].size, objects[i].position.y + objects[i].size);
s1 = new Vec2M(this.position.x, this.position.y);
p1 = s1.subV(p2);
p1.normalize();
p1 = p1.mulS(dist2 - this.strength - 50);
var end2 = p1.addV(p2);
ctx.lineTo(end2.x, end2.y);

var dir3 = {x: this.position.x, y: this.position.y};
vMath.subV(dir3, {x: objects[i].position.x + objects[i].size, y: objects[i].position.y});
var dist3 = vMath.length(dir3);

ctx.moveTo(objects[i].position.x + objects[i].size, objects[i].position.y);
p2 = new Vec2M(objects[i].position.x + objects[i].size, objects[i].position.y);
s1 = new Vec2M(this.position.x, this.position.y);
p1 = s1.subV(p2);
p1.normalize();
p1 = p1.mulS(dist3 - this.strength - 50);
var end3 = p1.addV(p2);
ctx.lineTo(end3.x, end3.y);

var dir4 = {x: this.position.x, y: this.position.y};
vMath.subV(dir4, {x: objects[i].position.x, y: objects[i].position.y + objects[i].size});
var dist4 = vMath.length(dir4);

ctx.moveTo(objects[i].position.x, objects[i].position.y + objects[i].size);
p2 = new Vec2M(objects[i].position.x, objects[i].position.y + objects[i].size);
s1 = new Vec2M(this.position.x, this.position.y);
p1 = s1.subV(p2);
p1.normalize();
p1 = p1.mulS(dist4 - this.strength - 50);
var end4 = p1.addV(p2);
ctx.lineTo(end4.x, end4.y);

ctx.moveTo(end4.x, end4.y);
ctx.lineTo(end1.x, end1.y);
ctx.lineTo(objects[i].position.x, objects[i].position.y);
ctx.lineTo(objects[i].position.x, objects[i].position.y + objects[i].size);
ctx.fill();

ctx.moveTo(end1.x, end1.y);
ctx.lineTo(end3.x, end3.y);
ctx.lineTo(objects[i].position.x + objects[i].size, objects[i].position.y);
ctx.lineTo(objects[i].position.x, objects[i].position.y);
ctx.fill();

ctx.moveTo(end3.x, end3.y);
ctx.lineTo(end2.x, end2.y);
ctx.lineTo(objects[i].position.x + objects[i].size, objects[i].position.y + objects[i].size);
ctx.lineTo(objects[i].position.x + objects[i].size, objects[i].position.y);
ctx.fill();

ctx.moveTo(end2.x, end2.y);
ctx.lineTo(end4.x, end4.y);
ctx.lineTo(objects[i].position.x, objects[i].position.y + objects[i].size);
ctx.lineTo(objects[i].position.x + objects[i].size, objects[i].position.y + objects[i].size);
ctx.fill();

ctx.stroke();