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index.html
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index.html
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<!DOCTYPE html>
<!--
Copyright 2011 Seth Ladd
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->
<html>
<head>
<meta charset="utf-8">
<title>Box2D Javascript Fun : 15 : Box2D with Pulley Joints and HTML5 Canvas</title>
<link rel="author" href="http://profiles.google.com/sethladd">
<script src="../Box2D.js"></script>
<script src="bTest.js"></script>
<style>
body {
-webkit-transform: translateZ(0);
}
</style>
</head>
<body>
<h1>Box2D with Pulley Joint and HTML5 Canvas</h1>
<canvas id="c0" width="640" height="480" style="border: 1px solid black"></canvas>
<p>
Black dot is the position of the object, the yellow dot is the center of mass.
</p>
<script async>
// http://paulirish.com/2011/requestanimationframe-for-smart-animating/
window.requestAnimFrame = (function(){
return window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.oRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function(/* function */ callback, /* DOMElement */ element){
window.setTimeout(callback, 1000 / 60);
};
})();
</script>
<script async>
var SCALE = 30;
var NULL_CENTER = {x:null, y:null};
function PulleyJoint(entity1, entity2, anchor1, anchor2) {
this.entity1 = entity1;
this.entity2 = entity2;
this.anchor1 = anchor1;
this.anchor2 = anchor2;
}
PulleyJoint.prototype.draw = function(ctx) {
this.drawLine(ctx, this.entity1, this.anchor1);
this.drawLine(ctx, this.entity2, this.anchor2);
}
PulleyJoint.prototype.drawLine = function(ctx, entity, anchor) {
ctx.beginPath();
ctx.strokeStyle = 'black';
ctx.moveTo(entity.x * SCALE, entity.y * SCALE);
ctx.lineTo(anchor.x * SCALE, anchor.y * SCALE);
ctx.closePath();
ctx.stroke();
}
function Entity(id, x, y, angle, center, color) {
this.id = id;
this.x = x;
this.y = y;
this.angle = angle || 0;
this.center = center;
this.color = color || "red";
}
Entity.prototype.update = function(state) {
this.x = state.x;
this.y = state.y;
this.center = state.c;
this.angle = state.a;
}
Entity.prototype.draw = function(ctx) {
ctx.fillStyle = 'black';
ctx.beginPath();
ctx.arc(this.x * SCALE, this.y * SCALE, 4, 0, Math.PI * 2, true);
ctx.closePath();
ctx.fill();
ctx.fillStyle = 'yellow';
ctx.beginPath();
ctx.arc(this.center.x * SCALE, this.center.y * SCALE, 2, 0, Math.PI * 2, true);
ctx.closePath();
ctx.fill();
}
Entity.build = function(def) {
if (def.radius) {
return new CircleEntity(def.id, def.x, def.y, def.angle, NULL_CENTER, def.color, def.radius);
} else if (def.polys) {
return new PolygonEntity(def.id, def.x, def.y, def.angle, NULL_CENTER, def.color, def.polys);
} else {
return new RectangleEntity(def.id, def.x, def.y, def.angle, NULL_CENTER, def.color, def.halfWidth, def.halfHeight);
}
}
function CircleEntity(id, x, y, angle, center, color, radius) {
color = color || 'aqua';
Entity.call(this, id, x, y, angle, center, color);
this.radius = radius;
}
CircleEntity.prototype = new Entity();
CircleEntity.prototype.constructor = CircleEntity;
CircleEntity.prototype.draw = function(ctx) {
ctx.save();
ctx.translate(this.x * SCALE, this.y * SCALE);
ctx.rotate(this.angle);
ctx.translate(-(this.x) * SCALE, -(this.y) * SCALE);
ctx.fillStyle = this.color;
ctx.strokeStyle = 'black';
ctx.beginPath();
ctx.arc(this.x * SCALE, this.y * SCALE, this.radius * SCALE, 0, Math.PI * 2, true);
ctx.moveTo(this.x * SCALE, this.y * SCALE);
ctx.lineTo((this.x) * SCALE, (this.y + this.radius) * SCALE);
ctx.closePath();
ctx.fill();
ctx.stroke();
ctx.restore();
Entity.prototype.draw.call(this, ctx);
}
function RectangleEntity(id, x, y, angle, center, color, halfWidth, halfHeight) {
Entity.call(this, id, x, y, angle, center, color);
this.halfWidth = halfWidth;
this.halfHeight = halfHeight;
}
RectangleEntity.prototype = new Entity();
RectangleEntity.prototype.constructor = RectangleEntity;
RectangleEntity.prototype.draw = function(ctx) {
ctx.save();
ctx.translate(this.x * SCALE, this.y * SCALE);
ctx.rotate(this.angle);
ctx.translate(-(this.x) * SCALE, -(this.y) * SCALE);
ctx.fillStyle = this.color;
ctx.fillRect((this.x-this.halfWidth) * SCALE,
(this.y-this.halfHeight) * SCALE,
(this.halfWidth*2) * SCALE,
(this.halfHeight*2) * SCALE);
ctx.restore();
Entity.prototype.draw.call(this, ctx);
}
function PolygonEntity(id, x, y, angle, center, color, polys) {
Entity.call(this, id, x, y, angle, center, color);
this.polys = polys;
}
PolygonEntity.prototype = new Entity();
PolygonEntity.prototype.constructor = PolygonEntity;
PolygonEntity.prototype.draw = function(ctx) {
ctx.save();
ctx.translate(this.x * SCALE, this.y * SCALE);
ctx.rotate(this.angle);
ctx.translate(-(this.x) * SCALE, -(this.y) * SCALE);
ctx.fillStyle = this.color;
for (var i = 0; i < this.polys.length; i++) {
var points = this.polys[i];
ctx.beginPath();
ctx.moveTo((this.x + points[0].x) * SCALE, (this.y + points[0].y) * SCALE);
for (var j = 1; j < points.length; j++) {
ctx.lineTo((points[j].x + this.x) * SCALE, (points[j].y + this.y) * SCALE);
}
ctx.lineTo((this.x + points[0].x) * SCALE, (this.y + points[0].y) * SCALE);
ctx.closePath();
ctx.fill();
ctx.stroke();
}
ctx.restore();
Entity.prototype.draw.call(this, ctx);
}
var world = {};
var bodiesState = null;
var box = null;
function update(animStart) {
if (isMouseDown) {
box.mouseDownAt(mouseX, mouseY);
} else if (box.isMouseDown()) {
box.mouseUp();
}
box.update();
bodiesState = box.getState();
for (var id in bodiesState) {
var entity = world[id];
if (entity) entity.update(bodiesState[id]);
}
}
var canvas = document.getElementById("c0");
var ctx = canvas.getContext("2d");
var canvasWidth = canvas.width;
var canvasHeight = canvas.height;
function draw() {
//console.log("d");
ctx.clearRect(0, 0, canvasWidth, canvasHeight);
for (var id in world) {
var entity = world[id];
entity.draw(ctx);
}
}
var initialState = [
{id: "ground", x: canvasWidth / 2 / SCALE, y: canvasHeight/ SCALE, halfHeight: 0.5, halfWidth: canvasWidth / SCALE, color: 'yellow'},
{id: "box1", x: 5, y: 6, halfHeight: 1, halfWidth: 1},
{id: "box2", x: 7, y: 6, halfHeight: 0.5, halfWidth: 0.5}
];
var running = true;
function init() {
for (var i = 0; i < initialState.length; i++) {
world[initialState[i].id] = Entity.build(initialState[i]);
}
box = new bTest(60, false, canvasWidth, canvasHeight, SCALE);
box.setBodies(world);
box.addPulleyJoint("box1", "box2", {x:5, y:1}, {x:7, y:1});
world['pulley'] = new PulleyJoint(world['box1'], world['box2'], {x:5, y:1}, {x:7, y:1});
setTimeout(function() {
init();
}, 7000);
}
/* ---- INPUT ----------------------------- */
var mouseX, mouseY, isMouseDown;
document.addEventListener("mousedown", function(e) {
isMouseDown = true;
handleMouseMove(e);
document.addEventListener("mousemove", handleMouseMove, true);
}, true);
document.addEventListener("mouseup", function() {
document.removeEventListener("mousemove", handleMouseMove, true);
isMouseDown = false;
mouseX = undefined;
mouseY = undefined;
}, true);
function handleMouseMove(e) {
mouseX = (e.clientX - canvas.getBoundingClientRect().left) / SCALE;
mouseY = (e.clientY - canvas.getBoundingClientRect().top) / SCALE;
};
/* ------------------------------------------ */
document.addEventListener("DOMContentLoaded", function() {
init();
(function loop(animStart) {
update(animStart);
draw();
requestAnimFrame(loop);
})();
}, false);
</script>
</body>
</html>