opc_sweepandprune.cpp

opcode是功能强大

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/*
 *	OPCODE - Optimized Collision Detection
 *	Copyright (C) 2001 Pierre Terdiman
 *	Homepage: http://www.codercorner.com/Opcode.htm
 */
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
 *	Contains an implementation of the sweep-and-prune algorithm (moved from Z-Collide)
 *	\file		OPC_SweepAndPrune.cpp
 *	\author		Pierre Terdiman
 *	\date		January, 29, 2000
 */
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Precompiled Header
#include "Opcode/Stdafx.h"

using namespace Opcode;

inline_ void Sort(udword& id0, udword& id1)
{
	if(id0>id1)	Swap(id0, id1);
}

	class Opcode::SAP_Element
	{
		public:
		inline_					SAP_Element()														{}
		inline_					SAP_Element(udword id, SAP_Element* next) : mID(id), mNext(next)	{}
		inline_					~SAP_Element()														{}

				udword			mID;
				SAP_Element*	mNext;
	};

	class Opcode::SAP_Box
	{
		public:
				SAP_EndPoint*	Min[3];
				SAP_EndPoint*	Max[3];
	};

	class Opcode::SAP_EndPoint
	{
		public:
				float			Value;		// Min or Max value
				SAP_EndPoint*	Previous;	// Previous EndPoint whose Value is smaller than ours (or null)
				SAP_EndPoint*	Next;		// Next EndPoint whose Value is greater than ours (or null)
				udword			Data;		// Parent box ID *2 | MinMax flag

		inline_	void			SetData(udword box_id, BOOL is_max)			{ Data = (box_id<<1)|is_max;	}
		inline_	BOOL			IsMax()								const	{ return Data & 1;				}
		inline_	udword			GetBoxID()							const	{ return Data>>1;				}

		inline_	void InsertAfter(SAP_EndPoint* element)
		{
			if(this!=element && this!=element->Next)
			{
				// Remove
				if(Previous)	Previous->Next = Next;
				if(Next)		Next->Previous = Previous;

				// Insert
				Next = element->Next;
				if(Next)	Next->Previous = this;

				element->Next = this;
				Previous = element;
			}
		}

		inline_	void InsertBefore(SAP_EndPoint* element)
		{
			if(this!=element && this!=element->Previous)
			{
				// Remove
				if(Previous)	Previous->Next = Next;
				if(Next)		Next->Previous = Previous;

				// Insert
				Previous = element->Previous;
				element->Previous = this;

				Next = element;
				if(Previous)	Previous->Next = this;
			}
		}
	};










///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
 *	Constructor.
 */
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
SAP_PairData::SAP_PairData() :
	mNbElements		(0),
	mNbUsedElements	(0),
	mElementPool	(null),
	mFirstFree		(null),
	mNbObjects		(0),
	mArray			(null)
{
}

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
 *	Destructor.
 */
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
SAP_PairData::~SAP_PairData()
{
	Release();
}

void SAP_PairData::Release()
{
	mNbElements		= 0;
	mNbUsedElements	= 0;
	mNbObjects		= 0;
	DELETEARRAY(mElementPool);
	DELETEARRAY(mArray);
}

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
 *	Initializes.
 *	\param		nb_objects	[in] 
 *	\return		true if success
 */
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
bool SAP_PairData::Init(udword nb_objects)
{
	// Make sure everything has been released
	Release();
	if(!nb_objects)	return false;

	mArray = new SAP_Element*[nb_objects];
	CHECKALLOC(mArray);
	ZeroMemory(mArray, nb_objects*sizeof(SAP_Element*));
	mNbObjects = nb_objects;

	return true;
}

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
 *	Remaps a pointer when pool gets resized.
 *	\param		element	[in/out] remapped element
 *	\param		delta	[in] offset in bytes
 */
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
inline_ void Remap(SAP_Element*& element, udword delta)
{
	if(element)	element = (SAP_Element*)(udword(element) + delta);
}

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
 *	Gets a free element in the pool.
 *	\param		id		[in] element id
 *	\param		next	[in] next element
 *	\param		remap	[out] possible remapping offset
 *	\return		the new element
 */
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
SAP_Element* SAP_PairData::GetFreeElem(udword id, SAP_Element* next, udword* remap)
{
	if(remap)	*remap = 0;

	SAP_Element* FreeElem;
	if(mFirstFree)
	{
		// Recycle
		FreeElem = mFirstFree;
		mFirstFree = mFirstFree->mNext;	// First free = next free (or null)
	}
	else
	{
		if(mNbUsedElements==mNbElements)
		{
			// Resize
			mNbElements = mNbElements ? (mNbElements<<1) : 2;

			SAP_Element* NewElems = new SAP_Element[mNbElements];

			if(mNbUsedElements)	CopyMemory(NewElems, mElementPool, mNbUsedElements*sizeof(SAP_Element));

			// Remap everything
			{
				udword Delta = udword(NewElems) - udword(mElementPool);

				for(udword i=0;i<mNbUsedElements;i++)	Remap(NewElems[i].mNext, Delta);
				for(udword i=0;i<mNbObjects;i++)		Remap(mArray[i], Delta);

				Remap(mFirstFree, Delta);
				Remap(next, Delta);

				if(remap)	*remap = Delta;
			}

			DELETEARRAY(mElementPool);
			mElementPool = NewElems;
		}

		FreeElem = &mElementPool[mNbUsedElements++];
	}

	FreeElem->mID = id;
	FreeElem->mNext = next;

	return FreeElem;
}

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
 *	Frees an element of the pool.
 *	\param		elem	[in] element to free/recycle
 */
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
inline_ void SAP_PairData::FreeElem(SAP_Element* elem)
{
	elem->mNext = mFirstFree;	// Next free
	mFirstFree = elem;
}

// Add a pair to the set.
void SAP_PairData::AddPair(udword id1, udword id2)
{
	// Order the ids
	Sort(id1, id2);

	ASSERT(id1<mNbObjects);
	if(id1>=mNbObjects)	return;

	// Select the right list from "mArray".
	SAP_Element* Current = mArray[id1];

	if(!Current)
	{
		// Empty slot => create new element
		mArray[id1] = GetFreeElem(id2, null);
	}
	else if(Current->mID>id2)
	{
		// The list is not empty but all elements are greater than id2 => insert id2 in the front.
		mArray[id1]	= GetFreeElem(id2, mArray[id1]);
	}
	else
	{
		// Else find the correct location in the sorted list (ascending order) and insert id2 there.
		while(Current->mNext)
		{
			if(Current->mNext->mID > id2)	break;

			Current = Current->mNext;
		}

		if(Current->mID==id2)	return;	// The pair already exists
		
//		Current->mNext = GetFreeElem(id2, Current->mNext);
		udword Delta;
		SAP_Element* E = GetFreeElem(id2, Current->mNext, &Delta);
		if(Delta)	Remap(Current, Delta);
		Current->mNext = E;
	}
}

// Delete a pair from the set.
void SAP_PairData::RemovePair(udword id1, udword id2)
{
	// Order the ids.
	Sort(id1, id2);

	// Exit if the pair doesn't exist in the set
	if(id1>=mNbObjects)	return;

	// Otherwise, select the correct list.
	SAP_Element* Current = mArray[id1];

	// If this list is empty, the pair doesn't exist.
	if(!Current) return;

	// Otherwise, if id2 is the first element, delete it.
	if(Current->mID==id2)
	{
		mArray[id1] = Current->mNext;
		FreeElem(Current);
	}
	else
	{
		// If id2 is not the first element, start traversing the sorted list.
		while(Current->mNext)
		{
			// If we have moved too far away without hitting id2, then the pair doesn't exist
			if(Current->mNext->mID > id2)	return;

			// Otherwise, delete id2.
			if(Current->mNext->mID == id2)
			{
				SAP_Element* Temp = Current->mNext;
				Current->mNext = Temp->mNext;
				FreeElem(Temp);
				return;
			}
			Current = Current->mNext;
		}
	}
}

void SAP_PairData::DumpPairs(Pairs& pairs) const
{
	// ### Ugly and slow
	for(udword i=0;i<mNbObjects;i++)
	{
		SAP_Element* Current = mArray[i];
		while(Current)
		{
			ASSERT(Current->mID<mNbObjects);

			pairs.AddPair(i, Current->mID);