source: code/branches/physics/src/bullet/BulletCollision/CollisionShapes/btCompoundShape.h @ 1983

/*
Bullet Continuous Collision Detection and Physics Library
Copyright (c) 2003-2006 Erwin Coumans  http://continuousphysics.com/Bullet/

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.
*/

#ifndef COMPOUND_SHAPE_H
#define COMPOUND_SHAPE_H

#include "btCollisionShape.h"

#include "LinearMath/btVector3.h"
#include "LinearMath/btTransform.h"
#include "LinearMath/btMatrix3x3.h"
#include "btCollisionMargin.h"
#include "LinearMath/btAlignedObjectArray.h"

//class btOptimizedBvh;
struct btDbvt;

ATTRIBUTE_ALIGNED16(struct) btCompoundShapeChild
{
        BT_DECLARE_ALIGNED_ALLOCATOR();

        btTransform                     m_transform;
        btCollisionShape*       m_childShape;
        int                                     m_childShapeType;
        btScalar                        m_childMargin;
        struct btDbvtNode*      m_node;
};

SIMD_FORCE_INLINE bool operator==(const btCompoundShapeChild& c1, const btCompoundShapeChild& c2)
{
        return  ( c1.m_transform      == c2.m_transform &&
                c1.m_childShape     == c2.m_childShape &&
                c1.m_childShapeType == c2.m_childShapeType &&
                c1.m_childMargin    == c2.m_childMargin );
}

/// btCompoundShape allows to store multiple other btCollisionShapes
/// This allows for moving concave collision objects. This is more general then the static concave btBvhTriangleMeshShape.
ATTRIBUTE_ALIGNED16(class) btCompoundShape      : public btCollisionShape
{
        //btAlignedObjectArray<btTransform>             m_childTransforms;
        //btAlignedObjectArray<btCollisionShape*>       m_childShapes;
        btAlignedObjectArray<btCompoundShapeChild> m_children;
        btVector3                                               m_localAabbMin;
        btVector3                                               m_localAabbMax;

        //btOptimizedBvh*                                       m_aabbTree;
        btDbvt*                                                 m_dynamicAabbTree;

public:
        BT_DECLARE_ALIGNED_ALLOCATOR();

        btCompoundShape();

        virtual ~btCompoundShape();

        void    addChildShape(const btTransform& localTransform,btCollisionShape* shape);

        /// Remove all children shapes that contain the specified shape
        virtual void removeChildShape(btCollisionShape* shape);

        void removeChildShapeByIndex(int childShapeindex);


        int             getNumChildShapes() const
        {
                return int (m_children.size());
        }

        btCollisionShape* getChildShape(int index)
        {
                return m_children[index].m_childShape;
        }
        const btCollisionShape* getChildShape(int index) const
        {
                return m_children[index].m_childShape;
        }

        btTransform     getChildTransform(int index)
        {
                return m_children[index].m_transform;
        }
        const btTransform       getChildTransform(int index) const
        {
                return m_children[index].m_transform;
        }


        btCompoundShapeChild* getChildList()
        {
                return &m_children[0];
        }

        ///getAabb's default implementation is brute force, expected derived classes to implement a fast dedicated version
        virtual void getAabb(const btTransform& t,btVector3& aabbMin,btVector3& aabbMax) const;

        /** Re-calculate the local Aabb. Is called at the end of removeChildShapes. 
        Use this yourself if you modify the children or their transforms. */
        virtual void recalculateLocalAabb(); 

        virtual void    setLocalScaling(const btVector3& scaling)
        {
                m_localScaling = scaling;
        }
        virtual const btVector3& getLocalScaling() const 
        {
                return m_localScaling;
        }

        virtual void    calculateLocalInertia(btScalar mass,btVector3& inertia) const;

        virtual void    setMargin(btScalar margin)
        {
                m_collisionMargin = margin;
        }
        virtual btScalar        getMargin() const
        {
                return m_collisionMargin;
        }
        virtual const char*     getName()const
        {
                return "Compound";
        }

        //this is optional, but should make collision queries faster, by culling non-overlapping nodes
        void    createAabbTreeFromChildren();

        btDbvt*                                                 getDynamicAabbTree()
        {
                return m_dynamicAabbTree;
        }

        ///computes the exact moment of inertia and the transform from the coordinate system defined by the principal axes of the moment of inertia
        ///and the center of mass to the current coordinate system. "masses" points to an array of masses of the children. The resulting transform
        ///"principal" has to be applied inversely to all children transforms in order for the local coordinate system of the compound
        ///shape to be centered at the center of mass and to coincide with the principal axes. This also necessitates a correction of the world transform
        ///of the collision object by the principal transform.
        void calculatePrincipalAxisTransform(btScalar* masses, btTransform& principal, btVector3& inertia) const;


private:
        btScalar        m_collisionMargin;
protected:
        btVector3       m_localScaling;

};



#endif //COMPOUND_SHAPE_H