Cocos2d-XNA 弹跳球不工作

创建了一个示例项目来测试Cocos2d和Box2d的弹跳球。

问题是球没有落下，我不知道为什么。重力设定好了，质量还可以，但球每一步都保持在同一位置。

class BouncingBallLayer : CCLayer
{
    int m_screen_width;
    int m_screen_height;
    CCSprite m_ball;
    b2Body m_body;
    b2World m_world;
    public BouncingBallLayer()
    {
        AccelerometerEnabled = false;
        var screen_size = CCDirector.SharedDirector.WinSize;
        m_screen_width = (int) screen_size.Width;
        m_screen_height = (int) screen_size.Height;
        m_ball = new CCSprite("assets/soccer-ball.png");
        m_ball.Position = new CCPoint(m_screen_width / 2, m_screen_height / 2);
        AddChild(m_ball);
        b2Vec2 gravity = new b2Vec2(0.0f, -8.0f);
        m_world = new b2World(gravity);
        m_world.AllowSleep = false;
        b2BodyDef ground_body_def = new b2BodyDef();
        ground_body_def.position.Set(0, 0);
        b2Body ground_body = m_world.CreateBody(ground_body_def);
        b2EdgeShape ground_edge = new b2EdgeShape();
        b2FixtureDef box_shape_def = new b2FixtureDef();
        box_shape_def.shape = ground_edge;
        ground_edge.Set(new b2Vec2(0, 0), new b2Vec2(m_screen_width / Constants.PTM_RATIO, 0));
        ground_body.CreateFixture(box_shape_def);
        ground_edge.Set(new b2Vec2(0, 0), new b2Vec2(0, m_screen_height / Constants.PTM_RATIO));
        ground_body.CreateFixture(box_shape_def);
        ground_edge.Set(new b2Vec2(0, m_screen_height / Constants.PTM_RATIO), new b2Vec2(m_screen_width / Constants.PTM_RATIO, m_screen_height / Constants.PTM_RATIO));
        ground_body.CreateFixture(box_shape_def);
        ground_edge.Set(new b2Vec2(m_screen_width / Constants.PTM_RATIO, m_screen_height / Constants.PTM_RATIO), new b2Vec2(m_screen_width / Constants.PTM_RATIO, 0));
        ground_body.CreateFixture(box_shape_def);
        b2BodyDef ball_body_def = new b2BodyDef();
        ball_body_def.type = b2BodyType.b2_dynamicBody;
        ball_body_def.position.Set(m_screen_width / 2 / Constants.PTM_RATIO, m_screen_height / 2 / Constants.PTM_RATIO);
        ball_body_def.userData = m_ball;
        m_body = m_world.CreateBody(ball_body_def);
        b2CircleShape circle = new b2CircleShape();
        circle.Radius = 26.0f / Constants.PTM_RATIO;
        b2FixtureDef ball_shape_def = new b2FixtureDef();
        ball_shape_def.shape = circle;
        ball_shape_def.density = 1.0f;
        ball_shape_def.friction = 0.2f;
        ball_shape_def.restitution = 0.8f;
        m_body.CreateFixture(ball_shape_def);
        this.Schedule(Tick);
    }

    void Tick(float dt)
    {
        int velocityIterations = 8;
        int positionIterations = 1;
        // Instruct the world to perform a single step of simulation. It is
        // generally best to keep the time step and iterations fixed.
        m_world.Step(dt, velocityIterations, positionIterations);
        //Iterate over the bodies in the physics world
        for (var b = m_world.BodyList; b != null; b = b.Next)
        {
            if (b.UserData != null)
            {
                //Synchronize the AtlasSprites position and rotation with the corresponding body
                var myActor = ((CCNode)b.UserData);
                myActor.PositionX = b.Position.x * Constants.PTM_RATIO;
                myActor.PositionY = b.Position.y * Constants.PTM_RATIO;
                myActor.Rotation = -1 * CCMacros.CCRadiansToDegrees(b.Angle);
            }
        }
    }

    public static CCScene Scene
    {
        get
        {
            // 'scene' is an autorelease object.
            var scene = new CCScene();
            // 'layer' is an autorelease object.
            var layer = new BouncingBallLayer();
            // add layer as a child to scene
            scene.AddChild(layer);
            // return the scene
            return scene;
        }
    }
}

顺便说一下，在调试时，我遇到以下异常。

"Bounce.vshost.exe"（托管 （v4.0.30319））：已加载'C：''Users''Максим''Projects''games''kicknrun''branches''cocos2d''KickNRun''Bounce''bin''WindowsGL''Debug''Bounce.exe'，已加载符号。

'Bounce.vshost.exe' （Managed （v4.0.30319））： Loaded 'C：''Users''Максим''Projects''games''kicknrun''branches''cocos2d''KickNRun''Bounce''bin''WindowsGL''Debug''MonoGame.Framework.dll'

"Bounce.vshost.exe"（托管 （v4.0.30319））：已加载'C：''Users''Максим''Projects''games''kicknrun''branches''cocos2d''KickNRun''Bounce''bin''WindowsGL''Debug''cocos2d-xna.dll'

"Bounce.vshost.exe"（托管 （v4.0.30319））：已加载'C：''Users''Максим''Projects''games''kicknrun''branches''cocos2d''KickNRun''Bounce''bin''WindowsGL''Debug''OpenTK.dll'

类型为"System.DllNotFoundException"的第一次机会异常发生在 OpenTK 中

.dll

在 OpenTK 中发生了类型为"System.TypeInitializationException"的第一次机会异常

.dll

在 OpenTK 中发生了类型为"System.DllNotFoundException"的第一次机会异常

.dll

类型为"System.DllNotFoundException"的第一次机会异常发生在MonoGame.Framework中.dll

'Bounce.vshost.exe' （Managed （v4.0.30319））： Loaded 'C：''Users''Максим''Projects''games''kicknrun''branches''cocos2d''KickNRun''Bounce''bin''WindowsGL''Debug''box2d.dll'

类型为"System.IO.FileNotFoundException"的第一次机会异常发生在姆科利布.dll

类型为"Microsoft.Xna.Framework.Content.ContentLoadException"的第一次机会异常发生在MonoGame.Framework中.dll

尽管这些 DLL 已加载。

<小时 />

还行！我终于构建了所有Cocos2d-xna东西的调试版本！看来，当世界被启动时，m_flags=b2WorldFlags.e_clearForces。这导致所有运动被重置！仍然必须找出如何解决这个问题！