iphone - 应该设置球的哪些物理属性？

Question

正在使用球的以下物理属性:

• 高尔夫球

  // Create circle shape
  b2CircleShape circle;
  circle.m_radius = 15.5/PTM_RATIO;
  
  // Create ball shape definition and add to body
  b2FixtureDef ballShapeDef;
  ballShapeDef.shape = &circle;
  ballShapeDef.density = 5000.0f;
  ballShapeDef.friction = 10.0f;
  ballShapeDef.restitution = 0.2f;
  
  ballFixture = ballBody->CreateFixture(&ballShapeDef);
  

• 板球

  // Create circle shape
  b2CircleShape circle;
  circle.m_radius = 17.0/PTM_RATIO;
  
  // Create ball shape definition and add to body
  b2FixtureDef ballShapeDef;
  ballShapeDef.shape = &circle;
  ballShapeDef.density = 5000.0f;
  ballShapeDef.friction = 10.0f;
  ballShapeDef.restitution = 0.4f;
  
  ballFixture = ballBody->CreateFixture(&ballShapeDef);
  

• 铁球

  // Create circle shape
  b2CircleShape circle;
  circle.m_radius = 23.0/PTM_RATIO;
  
  // Create ball shape definition and add to body
  b2FixtureDef ballShapeDef;
  ballShapeDef.shape = &circle;
  ballShapeDef.density = 5000.0f;
  ballShapeDef.friction = 10.0f;
  ballShapeDef.restitution = 0.0f;
  
  ballFixture = ballBody->CreateFixture(&ballShapeDef);
  

• 足球:

  // Create circle shape
  b2CircleShape circle;
  circle.m_radius = 24.0/PTM_RATIO;
  
  // Create ball shape definition and add to body
  b2FixtureDef ballShapeDef;
  ballShapeDef.shape = &circle;
  ballShapeDef.density = 5000.0f;
  ballShapeDef.friction = 10.0f;
  ballShapeDef.restitution = 0.8f;
  
  ballFixture = ballBody->CreateFixture(&ballShapeDef);
  

• 篮球:

  // Create circle shape
  b2CircleShape circle;
  circle.m_radius = 24.0/PTM_RATIO;
  
  // Create ball shape definition and add to body
  b2FixtureDef ballShapeDef;
  ballShapeDef.shape = &circle;
  ballShapeDef.density = 5000.0f;
  ballShapeDef.friction = 10.0f;
  ballShapeDef.restitution = 0.6f;        
  ballFixture = ballBody->CreateFixture(&ballShapeDef);
  

作为一个新手，我所实现的一切都是基于猜测，并且我遇到了一些麻烦，例如卡住的障碍物、倾斜障碍物上该死的慢动作等等，所以如果有更好的解决方案，请提出。

Answer 1

首先，我不建议您使用超过 100 的密度。它会提供糟糕的模拟效果。将密度保持在 1 - 100 范围内。就像动态物体的物体尺寸在 [0.1, 10] 范围内，静态物体的尺寸最大为 50(来自 box2d 文档)。通常摩擦力设置在 0 和 1 之间(也来自 box2d 文档)。因此，您必须在自己的单位中工作才能覆盖范围。例如，您可以测量密度为克每 1 立方米。

要评估球的密度，您需要知道它的半径和质量。在这种情况下，您可以发现密度为 m/V，其中 V 是体积。

要测量恢复原状，请在 YouTube 上查找一些视频，看看球抛出时弹跳的高度。恢复将为 h2/h1，其中 h1 初始高度，h2 - 弹跳后的高度