title: Unity3D Collider Passing Through Other Colliders
body: <p><strong>The Problem:</strong> Mesh colliders on <em>some</em> rigidbody objects are passing through colliders on other objects.</p>
  
  <p><strong>Things I have tried:</strong></p>
  
  <p>With the assumption A is a <code>GameObject</code> with a <code>RigidBody</code> attached and B is a normal <code>GameObject</code> with a collider.</p>
  
  <ul>
  <li>Give A a convex mesh collider</li>
  <li>Give A a non-convex mesh collider</li>
  <li>Give B a convex mesh collider</li>
  <li>Give B a non-convex mesh collider</li>
  <li>give B a box collider</li>
  <li>give B a convex mesh and box collider</li>
  <li>give B a non-convex mesh and box collider</li>
  <li>Adjusting the weight of the rigidbody</li>
  </ul>
  
  <p>I have tried all of these in all combinations of A and B.</p>
  
  <p>In addition,</p>
  
  <ul>
  <li>Colliders are not marked as triggers</li>
  <li>All objects are on the default layer (0)</li>
  <li>Checking isKinematic; doing this seemed to make gravity stop affecting the object, so I have left it as false.</li>
  </ul>
  
  <p><strong>Constraints:</strong> I want A to use a mesh collider since most of the objects involved are moderately complex, and fitting other colliders to them would take a while.</p>
  
  <p><strong>Weird Behaviour:</strong> I have some objects with both rigidbody and convex mesh collider where the collision is working fine with a non-convex mesh collider. This is inconsistent with other gameobjects. The objects have all of the same settings.</p>
  
  <p>I am using unity version 2019.3.11f1 if that is relevant.</p>
  
  <p>The object being used are from <a href="https://assetstore.unity.com/packages/3d/environments/low-poly-office-props-lite-131438" rel="nofollow noreferrer">this package</a>. Specifically, the filing cabinet with rigidbodies on the drawers works fine. The desk, office chair, pen, and open laptop all fall through the "floor" (a cube with all of the above colliders tested on it).</p>