01.Box2dWeb入门教程

2023-08-28 14:29:10
1.下载box2dweb.直接在页面中引用即可。
-Box2D.js是未压缩版
-Box2d.min.js是压缩版
2.编写HelloWorld代码。
<!DOCTYPE HTML>

<html>

    <head>

        <title>LaiXiao Box2DWeb Test</title>

        <script type="text/javascript" src="js/Box2D.js"></script>

    </head>

    <body onload="init();">

        <canvas id="canvas" width="600" height="400" style="background-color:#333333;"></canvas>

        <script>

        function init(){

            //方便使用

            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;

            //1.创建一个世界

            var world = new b2World(new b2Vec2(0,9.8),true);

            //2.创建一个矩形刚体

            //定义一个材质

            var fixDef = new b2FixtureDef;

            fixDef.density = 1.0;//密度

            fixDef.friction = 0.5;//摩擦

            fixDef.restitution = 0.2;//弹性

            fixDef.shape = new b2PolygonShape;//矩形

            fixDef.shape.SetAsBox(5, 0.5);//宽高

            //创建一个矩形地板刚体

            var bodyDef = new b2BodyDef;

            bodyDef.type = b2Body.b2_staticBody;//静态的

            bodyDef.position.x = 10;    //X轴

            bodyDef.position.y = 13;    //Y轴

            //世界中添加一个刚体

            world.CreateBody(bodyDef).CreateFixture(fixDef);

            //3.同上创建一个圆形刚体

            var fixDef2 = new b2FixtureDef;

            fixDef2.density = 1.0;

            fixDef2.friction = 0.5;

            fixDef2.restitution = 0.2;

            fixDef2.shape = new b2CircleShape(1);   

            var bodyDef2 = new b2BodyDef;

            bodyDef2.type = b2Body.b2_dynamicBody;

            bodyDef2.position.x = 9;

            bodyDef2.position.y = 1;

            world.CreateBody(bodyDef2).CreateFixture(fixDef2);

            //4.setup debug draw

            var debugDraw = new b2DebugDraw();

            debugDraw.SetSprite(document.getElementById("canvas").getContext("2d"));

            debugDraw.SetDrawScale(30.0);

            debugDraw.SetFillAlpha(0.3);

            debugDraw.SetLineThickness(1.0);

            debugDraw.SetFlags(b2DebugDraw.e_shapeBit | b2DebugDraw.e_jointBit);

            world.SetDebugDraw(debugDraw);

            //5.一帧帧执行

            window.setInterval(update, 1000 / 60);

            function update() {

                 //Take a time step.

                 world.Step(

                       1 / 60   //frame-rate

                    ,  10       //velocity iterations

                    ,  10       //position iterations

                 );

                 //Call this to draw shapes and other debug draw data.

                 world.DrawDebugData();

                 //Call this after you are done with time steps to clear the forces. You normally call this after each call to Step, unless you are performing sub-steps.

                 world.ClearForces();

                 //console.log(111);

            };

        }

        </script>

    </body>

</html>
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