text: /*
  * Copyright (c) 2006-2009 Erin Catto http://www.box2d.org
  *
  * This software is provided 'as-is', without any express or implied
  * warranty.  In no event will the authors be held liable for any damages
  * arising from the use of this software.
  * Permission is granted to anyone to use this software for any purpose,
  * including commercial applications, and to alter it and redistribute it
  * freely, subject to the following restrictions:
  * 1. The origin of this software must not be misrepresented; you must not
  * claim that you wrote the original software. If you use this software
  * in a product, an acknowledgment in the product documentation would be
  * appreciated but is not required.
  * 2. Altered source versions must be plainly marked as such, and must not be
  * misrepresented as being the original software.
  * 3. This notice may not be removed or altered from any source distribution.
  */
  
  #include <Box2D/Dynamics/b2WorldCallbacks.h>
  #include <Box2D/Dynamics/b2Fixture.h>
  
  // Return true if contact calculations should be performed between these two shapes.
  // If you implement your own collision filter you may want to build from this implementation.
  bool b2ContactFilter::ShouldCollide(b2Fixture* fixtureA, b2Fixture* fixtureB)
  {
  	const b2Filter& filterA = fixtureA->GetFilterData();
  	const b2Filter& filterB = fixtureB->GetFilterData();
  
  	if (filterA.groupIndex == filterB.groupIndex && filterA.groupIndex != 0)
  	{
  		return filterA.groupIndex > 0;
  	}
  
  	bool collide = (filterA.maskBits & filterB.categoryBits) != 0 && (filterA.categoryBits & filterB.maskBits) != 0;
  	return collide;
  }
  