Question

解析json字符串并将值传递给适当的Java类当我使用no-args时，为每个对象调用Gson构造函数然后我调用pulley.init(world);来实际向世界添加对象。

问题是对象被解析并加载到Box2d世界中 Pulley存在，有2个框，其中有一条线连接它们当场景被加载时，滑轮从天而降，慢慢地然后它突然跳出视线，整个世界变得非常缓慢这个设置是否适用于Pulley关节？我不知道为什么关节飞行在视线之外并导致这种退化。

json对象定义..

"pulleys":[
    {
        "anchorA_Low": 2.0,
        "anchorB_Low": 2.0,
        "anchorA_High": 10.0,
        "anchorB_High": 10.0,
        "ratio": 2.0,
        "shapeA": {
            "position": {
                "x": -30.0,
                "y": 10.0
            },
            "angle": 0.0,
            "width": 1.0,
            "height": 1.0,
            "bodyType": "DYNAMIC",
            "density": 5.0,
            "friction": 0.0,
            "restitution": 0.0,
        },
        "shapeB": {
            "position": {
                "x": -10.0,
                "y": 10.0
            },
            "angle": 0.0,
            "width": 1.0,
            "height": 1.0,
            "bodyType": "DYNAMIC",
            "density": 5.0,
            "friction": 0.0,
            "restitution": 0.0,
        }
    }
]

Pulley对象的Java类。

public class Pulley extends Joint{

    private Vec2 groundAnchorA;
    private Vec2 groundAnchorB;
    private Vec2 anchorA;
    private Vec2 anchorB;   
    private float anchorA_Low;
    private float anchorB_Low;
    private float anchorA_High;
    private float anchorB_High;
    private float ratio;

    public Pulley() {}

    public void init(World world){

            Body bodyA = getShapeA().setupShape(world);
            Body bodyB = getShapeB().setupShape(world);

            IAEdge edge = new IAEdge(bodyA.getPosition(), bodyB.getPosition());
            edge.init(world);

            anchorA = new Vec2(bodyA.getPosition().x, bodyA.getPosition().y + anchorA_Low);
            anchorB = new Vec2(bodyB.getPosition().x, bodyB.getPosition().y + anchorB_Low);

            groundAnchorA = new Vec2(bodyA.getPosition().x, bodyA.getPosition().y + anchorA_Low + anchorA_High);
            groundAnchorB = new Vec2(bodyB.getPosition().x, bodyB.getPosition().y + anchorB_Low + anchorB_High);

            PulleyJointDef pulleyDef = new PulleyJointDef();
            pulleyDef.initialize(bodyA, bodyB, groundAnchorA, groundAnchorB, anchorA, anchorB, ratio);
            world.createJoint(pulleyDef);
    }

    public Body setupShape(World world){

        PolygonShape blockShape = new PolygonShape();
        blockShape.setAsBox(getWidth() / 2, getHeight() / 2);

        FixtureDef fixtureDef = new FixtureDef();
        fixtureDef.shape = blockShape;
        fixtureDef.density = getDensity();
        fixtureDef.friction = getFriction();
        fixtureDef.restitution = getRestitution();

        BodyDef bodydef = new BodyDef();
        bodydef.type = BodyType.valueOf(getBodyType());
        bodydef.position.set(getPosition().x, getPosition().y);
        bodydef.angle = getAngle();

        Body body = world.createBody(bodydef);
        body.createFixture(fixtureDef);

        return body;
    }
}

封装Box2d的EdgeShape的Java类。

public class IAEdge {

    private Vec2 pointA;
    private Vec2 pointB;

    public IAEdge(){}

    public IAEdge(Vec2 pointA, Vec2 pointB){

        setPointA(pointA);
        setPointB(pointB);
    }

    public Body init(Level level) {

        BodyDef bd = new BodyDef();
        Body ground = level.createBody(bd);

        bd.position.set(
            new Vec2(
                ((pointA.x + pointB.x) / 2), 
                (pointA.y + pointB.y) / 2));

        EdgeShape shape = new EdgeShape();
        shape.set(
            new Vec2(pointA.x, pointA.y), 
            new Vec2(pointB.x, pointB.y));

        ground.createFixture(shape, 0.0f);

        return ground;
    }
}

Answer 1

这是jbox2d中的错误，已在2.3.1-SNAPSHOT

中修复

滑轮关节弹出视线并减缓世界

1 个答案: