预知者，单配游戏，球不弹

Question

我已经成功地将《Farseer for XNA》整合到《MonoGame》中。堆叠、复杂动态等似乎都行得通，但我绝对不能让球在地板上弹跳。当球接触地面时，它只是停在那里，只有在受到另一个球的推动时才会移动。

我的代码(在f#中，但它应该足够清晰;<-表示赋值，其他都和c#一样)创建球和地的方法是:

  member physics.CreateBall(x:float32<m>,y:float32<m>,r:float32<m>,m:float32<kg>,dynamic:bool) =
    let myBody = Factories.BodyFactory.CreateBody(physics.Physics, Microsoft.Xna.Framework.Vector2(x * 1.0f<1/m> + random_range -30.0f 30.0f, y * 1.0f<1/m>) * PhysicsWorld.Scale)
    do myBody.LastFrameUpdate <- Casanova.Core.get_frame_counter()
    do myBody.BodyType <- if dynamic then BodyType.Dynamic else BodyType.Static
    do myBody.Restitution <- 1.0f
    do myBody.Friction <- 0.0f
    do myBody.Mass <- m * 1.0f<_>
    let circleShape = new CircleShape(r * PhysicsWorld.Scale * 1.0f<1/m>, 1.0f)
    let fixture = myBody.CreateFixture(circleShape)
    { Body = myBody; Tick = Rule.Create 0 }
  member physics.CreateBox(x:float32<m>,y:float32<m>,w:float32<m>,h:float32<m>,m:float32<kg>,dynamic:bool) =
    let myBody = Factories.BodyFactory.CreateBody(physics.Physics, Microsoft.Xna.Framework.Vector2(x * 1.0f<1/m>, y * 1.0f<1/m>) * PhysicsWorld.Scale)
    do myBody.LastFrameUpdate <- Casanova.Core.get_frame_counter()
    do myBody.BodyType <- if dynamic then BodyType.Dynamic else BodyType.Static
    do myBody.Restitution <- 1.0f
    do myBody.Friction <- 0.0f
    do myBody.Mass <- m * 1.0f<_>
    let rectangle = PolygonTools.CreateRectangle(w * PhysicsWorld.Scale * 1.0f<1/m>, h * PhysicsWorld.Scale * 1.0f<1/m>)
    let boxShape = PolygonShape(rectangle, 1.0f)
    let fixture = myBody.CreateFixture(boxShape)
    { Body = myBody; Tick = Rule.Create 0 }

Answer 1

最简单的解决方案。除去初始化顺序，上面的代码几乎是正确的。以下是供将来参考的工作版本:

let myBody = Factories.BodyFactory.CreateBody(physics.Physics, Microsoft.Xna.Framework.Vector2(x * 1.0f<1/m>, y * 1.0f<1/m>) * PhysicsWorld.Scale)
let rectangle = PolygonTools.CreateRectangle(w * PhysicsWorld.Scale * 1.0f<1/m>, h * PhysicsWorld.Scale * 1.0f<1/m>)
let boxShape = PolygonShape(rectangle, 1.0f)
let fixture = myBody.CreateFixture(boxShape)
do myBody.LastFrameUpdate <- Casanova.Core.get_frame_counter()
do myBody.BodyType <- if dynamic then BodyType.Dynamic else BodyType.Static
do myBody.Restitution <- restitution
do myBody.Friction <- friction
do myBody.Mass <- m * 1.0f<_>