Box2D:物体

box2d教程讲解的很详细，不做赘余

#define DEGTORAD 0.0174532925199432957f
class FooTest : public Test{
    public:
        FooTest() {
			//创建物体
			b2BodyDef myBodyDef;
			myBodyDef.type = b2_dynamicBody;//物体类型，3种，如下
			myBodyDef.position.Set(0,20);//位置
			myBodyDef.angle = 0;//角度
			//create
			dynamicBody = m_world->CreateBody(&myBodyDef);

			
			b2PolygonShape boxShape;
			boxShape.SetAsBox(1,1);//物体大小

			//动态物体
			b2FixtureDef boxFixtureDef;
			boxFixtureDef.shape = &boxShape;
			boxFixtureDef.density = 1;
			dynamicBody->CreateFixture(&boxFixtureDef);//定制器
			dynamicBody->SetTransform(b2Vec2(10, 20), 45*DEGTORAD);//角度
			dynamicBody->SetLinearVelocity(b2Vec2(-5, 5));//线速度
			dynamicBody->SetAngularVelocity(-90*DEGTORAD);//角速度

			//静态物体
			myBodyDef.type = b2_staticBody;
			myBodyDef.position.Set(0, 10);
			staticBody = m_world->CreateBody(&myBodyDef);
			staticBody->CreateFixture(&boxFixtureDef);

			//动力学物体
			myBodyDef.type = b2_kinematicBody;
			myBodyDef.position.Set(-18, 11);
			kinermaticBody = m_world->CreateBody(&myBodyDef);
			kinermaticBody->CreateFixture(&boxFixtureDef);

			kinermaticBody->SetLinearVelocity(b2Vec2(1, 0));
			kinermaticBody->SetAngularVelocity(360*DEGTORAD);
			//dynamicBody = kinermaticBody;
		} //do nothing, no scene yet
		
        void Step(Settings* settings){
            //run the default physics and rendering
            Test::Step(settings);

            //show some text in the main screen
            m_debugDraw.DrawString(5, m_textLine, "Now we have a foo test");
            m_textLine += 15;
			if(dynamicBody){
				b2Vec2 pos = dynamicBody->GetPosition();
				float angle = dynamicBody->GetAngle();
				b2Vec2 ve1 = dynamicBody->GetLinearVelocity();
				float angularve1 = dynamicBody->GetAngularVelocity();

				m_debugDraw.DrawString(5, m_textLine, "Position: %.3f, %.3f Angle: %.3f", pos.x, pos.y, angle * DEGTORAD);
				m_textLine += 15;
				m_debugDraw.DrawString(5, m_textLine, "velocity: %.3f, %.3f velocity: %.3f", ve1.x, ve1.y, angularve1 * DEGTORAD);
				m_textLine += 15; 
				if(pos.y <= 10){
					m_world->DestroyBody(dynamicBody);
					dynamicBody = NULL;
				}
			}
		}
		
         static Test* Create(){
            return new FooTest;
         }
		 
		b2Body* dynamicBody;
		b2Body* staticBody;
		b2Body* kinermaticBody;
};