如何创建简单的减速后拖拽和Box2d对象？(Actionscript 3)

Question

所以我需要做的很简单--如何用flex4和AS3创建一个可拖放的圆，并用Box2d让它沿着拖拽的方向飞得更远，而不是停下来？

Answer 1

使用LinearDamping。

这就是我如何在我的自上而下的射击中使用它来减慢对象，如果线速度停止被应用的话。

//Body is created using body definition
var b:b2Body = GameCore.environment.world.CreateBody(bodyDef);

//Fixture definition holds data such as density, friction and shape
var fixtureDef:b2FixtureDef;
fixtureDef = new b2FixtureDef();

//Define vertices etc in polygon shape
var shape:b2CircleShape;
shape = new b2CircleShape(Values.ptm(_diameter / 2));

//Assign values
fixtureDef.shape = shape;
fixtureDef.density = 1.5;
fixtureDef.friction = 0.3;
fixtureDef.restitution = 0.45;

//Add fixture to appropriate body
b.CreateFixture(fixtureDef);    

//Movement Physics Settings
b.SetLinearDamping(_linearDamping);
b.SetAngularDamping(_angularDamping);

Answer 2

您可能希望确保关闭重力(两个维度均为零)，例如

var gravity:b2Vec2 = new b2Vec2 (0.0, 0.0);

然后让摩擦力减慢速度。