title: Assertion failed: (fixture->m_body == this)
body: <p>We have two vectors of fixtures (all of one body) </p>
  
  <pre><code>//Create and add fixtures to vector1 and vector2
  b2PolygonShape shape1;
  shape1.SetAsEdge(from1,to1);
  vector1.push_back( body1-&gt;CreateFixture(&amp;shape1,0) );
  
  b2PolygonShape shape2;
  shape2.SetAsEdge(from2,to2);
  vector2.push_back( body2-&gt;CreateFixture(&amp;shape2,0) );
  </code></pre>
  
  <p>When case event1, we destroy first fixture in vector1.</p>
  
  <pre><code>body1-&gt;DestroyFixture( vector1[0] ); //destroy first fixture1
  vector1.erase( vector1.begin() ); //remove from vector1
  </code></pre>
  
  <p>When case event2, we destroy first fixture in vector2.</p>
  
  <pre><code>body2-&gt;DestroyFixture( vector2[0] ); //destroy first fixture2
  vector2.erase( vector2.begin() ); //remove from vector2
  </code></pre>
  
  <p><strong>Problem:</strong>
  Sometimes, when we DestroyFixture(...), we get "<strong>Assertion failed: (fixture->m_body == this)</strong>"</p>
  
  <p>I checked, and I know that vector1 can have some fixture2, or vector2 have fixture1. Why it can be? 
  I add fixture1 only to vector1, and fixture2 only to vector2.</p>