我怎样才能让我的物理对象安定下来？

Posted 2023-02-15

【中文标题】我怎样才能让我的物理对象安定下来？

【英文标题】：How can I make my physics object settle down?

【发布时间】：2012-06-03 03:24:01

【问题描述】：

我正在使用 BulletSharp，它是子弹库的 C# 发行版。我在一个据称具有 0.0f 的 Restitution 的对象中出现了一些弹跳。

我有一个动态圆柱体（即将成为网格）落在两个静态圆​​柱体上。像这样：

顶部的圆柱体经常疯狂地弹跳，通常弹到一边。

这是我用来设置场景的代码：

        //now figure out bulletsharp stuff...
        CollisionConfiguration collConfig = new DefaultCollisionConfiguration();
        Dispatcher collDispatch = new CollisionDispatcher(collConfig);

        BroadphaseInterface broadphase = new DbvtBroadphase();
        ConstraintSolver sol = new SequentialImpulseConstraintSolver();
        world = new DiscreteDynamicsWorld(collDispatch, broadphase, sol, collConfig);

        world.Gravity = new Vector3(0.0f, -10.0f, 0.0f);

        //log (moving object)
        MotionState still = new DefaultMotionState();
        CylinderShape shape = new CylinderShapeZ(0.5f, 1.0f, 1.0f);
        still.WorldTransform = Matrix.Translation(0.0f, 0.4f, 0.0f);
        RigidBodyConstructionInfo constructInfo = new RigidBodyConstructionInfo(1.0f, still, shape);
        logBody = new RigidBody(constructInfo);
        logBody.SetDamping(0.04f, 0.1f);
        world.AddRigidBody(logBody);

        //rollers (static objects)
        CylinderShape r1s = new CylinderShapeZ(0.1f, 1.0f, 1.0f);
        MotionState r1m = new DefaultMotionState();
        r1m.WorldTransform = Matrix.Translation(-0.2f, -0.4f, 0.0f);
        RigidBodyConstructionInfo r1ci = new RigidBodyConstructionInfo(0.0f, r1m, r1s);
        r1 = new RigidBody(r1ci);
        world.AddRigidBody(r1);

        CylinderShape r2s = new CylinderShapeZ(0.1f, 1.0f, 1.0f);
        MotionState r2m = new DefaultMotionState();
        r2m.WorldTransform = Matrix.Translation(0.2f, -0.4f, 0.0f);
        RigidBodyConstructionInfo r2ci = new RigidBodyConstructionInfo(0.0f, r2m, r2s);
        r2 = new RigidBody(r2ci);
        world.AddRigidBody(r2);

我使用world.StepSimulation(0.05f, 100, 0.0005f); 更新物理模拟的每一帧。

我是否遗漏了任何明显的设置？为什么我的模拟会这样做？

小更新：我已经成功地在 Blender 的 Bullet 中进行了类似的模拟。那里没有弹跳……我不知道那和这之间可能有什么区别。

【问题讨论】：

你可以为坠落的物体添加恢复原状吗？

仅对坠落的物体添加恢复原状并没有产生任何明显的差异。将所有三个对象的恢复原状设置为 0.1 似乎会稍微稳定下来，但这取决于模拟步长。还是有一点弹跳，偶尔弹跳。

【参考方案1】：

您没有在模型中添加惯性。这应该会减慢抖动，并且不会产生最终从滚轮反弹的混响。您需要为所有三个对象添加它，包括滚轮上的零。试试这个，让我知道它是如何工作的：

//now figure out bulletsharp stuff...
CollisionConfiguration collConfig = new DefaultCollisionConfiguration();
Dispatcher collDispatch = new CollisionDispatcher(collConfig);

BroadphaseInterface broadphase = new DbvtBroadphase();
ConstraintSolver sol = new SequentialImpulseConstraintSolver();
world = new DiscreteDynamicsWorld(collDispatch, broadphase, sol, collConfig);

world.Gravity = new Vector3(0.0f, -10.0f, 0.0f);

//log (moving object)
Vector3 cylinderInertia;
MotionState still = new DefaultMotionState();
CylinderShape shape = new CylinderShapeZ(0.5f, 1.0f, 1.0f);
still.WorldTransform = Matrix.Translation(0.0f, 0.4f, 0.0f);
shape.CalculateLocalInertia(1.0f, out cylinderInertia);    
RigidBodyConstructionInfo constructInfo = new RigidBodyConstructionInfo(1.0f, still, shape, cylinderInertia);
logBody = new RigidBody(constructInfo);
logBody.SetDamping(0.04f, 0.1f);
world.AddRigidBody(logBody);

//rollers (static objects)
CylinderShape r1s = new CylinderShapeZ(0.1f, 1.0f, 1.0f);
MotionState r1m = new DefaultMotionState();
r1m.WorldTransform = Matrix.Translation(-0.2f, -0.4f, 0.0f);
RigidBodyConstructionInfo r1ci = new RigidBodyConstructionInfo(0.0f, r1m, r1s, Vector3.Zero);
r1 = new RigidBody(r1ci);
world.AddRigidBody(r1);

CylinderShape r2s = new CylinderShapeZ(0.1f, 1.0f, 1.0f);
MotionState r2m = new DefaultMotionState();
r2m.WorldTransform = Matrix.Translation(0.2f, -0.4f, 0.0f);
RigidBodyConstructionInfo r2ci = new RigidBodyConstructionInfo(0.0f, r2m, r2s, Vector3.Zero);
r2 = new RigidBody(r2ci);
world.AddRigidBody(r2);