simple collision detection with box2dweb
- by skywalker
im beginner in box2dweb that version of box2d for javascript
i wrote simple gravity system and i want to detect the collision between the box and the ground , when the falling box hit the ground execute simple function like function sucs(){alert("the box on the floor !")};
this is my code
var CANVAS_WIDTH = 1024, CANVAS_HEIGHT = 700, SCALE = 30;
var b2Vec2 = Box2D.Common.Math.b2Vec2
, b2BodyDef = Box2D.Dynamics.b2BodyDef
, b2Body = Box2D.Dynamics.b2Body
, b2FixtureDef = Box2D.Dynamics.b2FixtureDef
, b2Fixture = Box2D.Dynamics.b2Fixture
, b2World = Box2D.Dynamics.b2World
, b2MassData = Box2D.Collision.Shapes.b2MassData
, b2PolygonShape = Box2D.Collision.Shapes.b2PolygonShape
, b2CircleShape = Box2D.Collision.Shapes.b2CircleShape
, b2DebugDraw = Box2D.Dynamics.b2DebugDraw;
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
var world = new b2World(new b2Vec2(0, 8), true);
var fixDef = new b2FixtureDef();
var bodyDef = new b2BodyDef();
fixDef.density = 1.0;
fixDef.friction = 0.5;
bodyDef.type = b2Body.b2_staticBody;
fixDef.shape = new b2PolygonShape;
fixDef.shape.SetAsBox(20, 2);
bodyDef.position.Set(10, 400 / 30 + 1.8);
world.CreateBody(bodyDef).CreateFixture(fixDef);
fixDef.density = 1.0;
fixDef.friction = 0.5;
fixDef.restitution = 0.3;
bodyDef.type = b2Body.b2_dynamicBody;
bodyDef.position.Set(50 / SCALE, 0 / SCALE);
//bodyDef.linearVelocity.Set((Math.random() * 12) + 2, (Math.random() * 12) + 2);
fixDef.shape = new b2PolygonShape();
fixDef.shape.SetAsBox(25 / SCALE, 25 / SCALE);
world.CreateBody(bodyDef).CreateFixture(fixDef);
var debugDraw = new b2DebugDraw();
debugDraw.SetSprite(document.getElementById("canvas").getContext("2d"));
debugDraw.SetDrawScale(30.0);
debugDraw.SetFillAlpha(0.5);
debugDraw.SetLineThickness(1.0);
debugDraw.SetFlags(b2DebugDraw.e_shapeBit | b2DebugDraw.e_jointBit);
world.SetDebugDraw(debugDraw);
var image = new Image();
image.src = "image.png";
window.setInterval(gameLoop, 1000 / 60);
function gameLoop() {
world.Step(1 / 60, 8, 3);
world.ClearForces();
context.clearRect(0, 0, CANVAS_WIDTH, CANVAS_HEIGHT);
b = world.GetBodyList()
var pos = b.GetPosition();
context.save();
context.translate(pos.x * SCALE, pos.y * SCALE);
context.rotate(b.GetAngle());
context.drawImage(image, -25, -25);
context.restore();
b = b.GetNext();
pos = b.GetPosition();
context.save();
context.translate(pos.x * SCALE, pos.y * SCALE);
//b.GetAngle()++;
context.rotate(b.GetAngle());
context.drawImage(image, -25, -25);
context.restore();
world.DrawDebugData();
};
