1 files changed, 375 insertions, 0 deletions
diff --git a/indra/llprimitive/llprimlinkinfo.h b/indra/llprimitive/llprimlinkinfo.h
new file mode 100644
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--- /dev/null
+++ b/indra/llprimitive/llprimlinkinfo.h
@@ -0,0 +1,375 @@
+/** 
+ * @file llprimlinkinfo.h
+ * @author andrew@lindenlab.com
+ * @brief A template for determining which prims in a set are linkable
+ *
+ * Copyright (c) 2007-$CurrentYear$, Linden Research, Inc.
+ * $License$
+ */
+
+
+#ifndef LL_PRIM_LINK_INFO_H
+#define LL_PRIM_LINK_INFO_H
+
+// system includes
+#include <iostream>
+#include <map>
+#include <list>
+#include <vector>
+
+// common includes
+#include "stdtypes.h"
+#include "v3math.h"
+#include "llquaternion.h"
+#include "llsphere.h"
+
+
+const F32 MAX_OBJECT_SPAN = 54.f;		// max distance from outside edge of an object to the farthest edge
+const F32 OBJECT_SPAN_BONUS = 2.f;		// infinitesimally small prims can always link up to this distance
+const S32 MAX_PRIMS_PER_OBJECT = 255;
+
+
+template < typename DATA_TYPE >
+class LLPrimLinkInfo
+{
+public:
+	LLPrimLinkInfo();
+	LLPrimLinkInfo( DATA_TYPE data, const LLSphere& sphere );
+	~LLPrimLinkInfo();
+
+	void set( DATA_TYPE data, const LLSphere& sphere );
+	void append( DATA_TYPE data, const LLSphere& sphere );
+	void getData( std::list< DATA_TYPE >& data_list ) const;
+	F32 getDiameter() const;
+	LLVector3 getCenter() const;
+
+	// returns 'true' if this info can link with other_info
+	bool canLink( const LLPrimLinkInfo< DATA_TYPE >& other_info );
+
+	S32 getPrimCount() const { return mDataMap.size(); }
+
+	void mergeLinkableSet( typename std::list< LLPrimLinkInfo < DATA_TYPE > >& unlinked );
+
+	void transform(const LLVector3& position, const LLQuaternion& rotation);
+
+private:
+	// returns number of merges made
+	S32 merge(LLPrimLinkInfo< DATA_TYPE >& other_info);
+
+	// returns number of collapses made
+	static S32 collapse(typename std::list< LLPrimLinkInfo < DATA_TYPE > >& unlinked );
+
+	void computeBoundingSphere();
+
+	// Internal utility to encapsulate the link rules
+	F32 get_max_linkable_span(const LLSphere& first, const LLSphere& second);
+	F32 get_span(const LLSphere& first, const LLSphere& second);
+
+private:
+	std::map< DATA_TYPE, LLSphere > mDataMap;
+	LLSphere mBoundingSphere;
+};
+
+
+
+template < typename DATA_TYPE >
+LLPrimLinkInfo< DATA_TYPE >::LLPrimLinkInfo()
+:	mBoundingSphere( LLVector3(0.f, 0.f, 0.f), 0.f )
+{
+}
+
+template < typename DATA_TYPE >
+LLPrimLinkInfo< DATA_TYPE >::LLPrimLinkInfo( DATA_TYPE data, const LLSphere& sphere)
+:	mBoundingSphere(sphere)
+{
+	mDataMap[data] = sphere;
+}
+
+template < typename DATA_TYPE >
+LLPrimLinkInfo< DATA_TYPE >::~LLPrimLinkInfo()
+{
+	mDataMap.clear();
+}
+
+template < typename DATA_TYPE >
+void LLPrimLinkInfo< DATA_TYPE>::set( DATA_TYPE data, const LLSphere& sphere )
+{
+	if (!mDataMap.empty())
+	{
+		mDataMap.clear();
+	}
+	mDataMap[data] = sphere;
+	mBoundingSphere = sphere;
+}
+
+template < typename DATA_TYPE >
+void LLPrimLinkInfo< DATA_TYPE>::append( DATA_TYPE data, const LLSphere& sphere )
+{
+	mDataMap[data] = sphere;
+	if (!mBoundingSphere.contains(sphere))
+	{
+		computeBoundingSphere();
+	}
+}
+
+template < typename DATA_TYPE >
+void LLPrimLinkInfo< DATA_TYPE >::getData( std::list< DATA_TYPE >& data_list) const
+{
+	typename std::map< DATA_TYPE, LLSphere >::const_iterator map_itr;
+	for (map_itr = mDataMap.begin(); map_itr != mDataMap.end(); ++map_itr)
+	{
+		data_list.push_back(map_itr->first);
+	}
+}
+
+template < typename DATA_TYPE >
+F32 LLPrimLinkInfo< DATA_TYPE >::getDiameter() const
+{ 
+	return 2.f * mBoundingSphere.getRadius();
+}
+
+template < typename DATA_TYPE >
+LLVector3 LLPrimLinkInfo< DATA_TYPE >::getCenter() const
+{ 
+	return mBoundingSphere.getCenter(); 
+}
+
+template < typename DATA_TYPE >
+F32 LLPrimLinkInfo< DATA_TYPE >::get_max_linkable_span(const LLSphere& first, const LLSphere& second)
+{
+	F32 max_span = 3.f * (first.getRadius() + second.getRadius()) + OBJECT_SPAN_BONUS;
+	if (max_span > MAX_OBJECT_SPAN)
+	{
+		max_span = MAX_OBJECT_SPAN;
+	}
+
+	return max_span;
+}
+
+template < typename DATA_TYPE >
+F32 LLPrimLinkInfo< DATA_TYPE >::get_span(const LLSphere& first, const LLSphere& second)
+{
+	F32 span = (first.getCenter() - second.getCenter()).length()
+				+ first.getRadius() + second.getRadius();
+	return span;
+}
+
+// static
+// returns 'true' if this info can link with any part of other_info
+template < typename DATA_TYPE >
+bool LLPrimLinkInfo< DATA_TYPE >::canLink(const LLPrimLinkInfo& other_info)
+{
+	F32 max_span = get_max_linkable_span(mBoundingSphere, other_info.mBoundingSphere);
+
+	F32 span = get_span(mBoundingSphere, other_info.mBoundingSphere);
+	
+	if (span <= max_span)
+	{
+		// The entire other_info fits inside the max span.
+		return TRUE;
+	}
+	else if (span > max_span + 2.f * other_info.mBoundingSphere.getRadius())
+	{
+		// there is no way any piece of other_info could link with this one
+		return FALSE;
+	}
+
+	// there may be a piece of other_info that is linkable
+	typename std::map< DATA_TYPE, LLSphere >::const_iterator map_itr;
+	for (map_itr = other_info.mDataMap.begin(); map_itr != other_info.mDataMap.end(); ++map_itr)
+	{
+		const LLSphere& other_sphere = (*map_itr).second;
+		max_span = get_max_linkable_span(mBoundingSphere, other_sphere);
+
+		span = get_span(mBoundingSphere, other_sphere);
+
+		if (span <= max_span)
+		{
+			// found one piece that is linkable
+			return TRUE;
+		}
+	}
+	return FALSE;
+}
+
+// merges elements of 'unlinked' 
+// returns number of links made (NOT final prim count, NOR linked prim count)
+// and removes any linkable infos from 'unlinked' 
+template < typename DATA_TYPE >
+void LLPrimLinkInfo< DATA_TYPE >::mergeLinkableSet(std::list< LLPrimLinkInfo< DATA_TYPE > > & unlinked)
+{
+	bool linked_something = true;
+	while (linked_something)
+	{
+		linked_something = false;
+
+		typename std::list< LLPrimLinkInfo< DATA_TYPE > >::iterator other_itr = unlinked.begin();
+		while ( other_itr != unlinked.end()
+			   && getPrimCount() < MAX_PRIMS_PER_OBJECT )
+		{
+			S32 merge_count = merge(*other_itr);
+			if (merge_count > 0)
+			{
+				linked_something = true;
+			}
+			if (0 == (*other_itr).getPrimCount())
+			{
+				unlinked.erase(other_itr++);
+			}
+			else
+			{
+				++other_itr;
+			}
+		}
+		if (!linked_something
+			&& unlinked.size() > 1)
+		{
+			S32 collapse_count = collapse(unlinked);
+			if (collapse_count > 0)
+			{
+				linked_something = true;
+			}
+		}
+	}
+}
+
+// transforms all of the spheres into a new reference frame
+template < typename DATA_TYPE >
+void LLPrimLinkInfo< DATA_TYPE >::transform(const LLVector3& position, const LLQuaternion& rotation)
+{
+	typename std::map< DATA_TYPE, LLSphere >::iterator map_itr;
+	for (map_itr = mDataMap.begin(); map_itr != mDataMap.end(); ++map_itr)
+	{
+		(*map_itr).second.setCenter((*map_itr).second.getCenter() * rotation + position);
+	}
+	mBoundingSphere.setCenter(mBoundingSphere.getCenter() * rotation + position);
+}
+
+// private
+// returns number of links made
+template < typename DATA_TYPE >
+S32 LLPrimLinkInfo< DATA_TYPE >::merge(LLPrimLinkInfo& other_info)
+{
+	S32 link_count = 0;
+
+//	F32 other_radius = other_info.mBoundingSphere.getRadius();
+//	other_info.computeBoundingSphere();
+//	if ( other_radius != other_info.mBoundingSphere.getRadius() )
+//	{
+//		llinfos << "Other bounding sphere changed!!" << llendl;
+//	}
+
+//	F32 this_radius = mBoundingSphere.getRadius();
+//	computeBoundingSphere();
+//	if ( this_radius != mBoundingSphere.getRadius() )
+//	{
+//		llinfos << "This bounding sphere changed!!" << llendl;
+//	}
+
+
+	F32 max_span = get_max_linkable_span(mBoundingSphere, other_info.mBoundingSphere);
+
+	//  F32 center_dist = (mBoundingSphere.getCenter() - other_info.mBoundingSphere.getCenter()).length();
+	//	llinfos << "objects are " << center_dist << "m apart" << llendl;
+	F32 span = get_span(mBoundingSphere, other_info.mBoundingSphere);
+
+	F32 span_limit = max_span + (2.f * other_info.mBoundingSphere.getRadius());
+	if (span > span_limit)
+	{
+		// there is no way any piece of other_info could link with this one
+		// llinfos << "span too large:  " << span << " vs. " << span_limit << llendl;
+		return 0;
+	}
+
+	bool completely_linkable = (span <= max_span) ? true : false;
+
+	typename std::map< DATA_TYPE, LLSphere >::iterator map_itr = other_info.mDataMap.begin();
+	while (map_itr != other_info.mDataMap.end()
+			&& getPrimCount() < MAX_PRIMS_PER_OBJECT )
+	{
+		DATA_TYPE other_data = (*map_itr).first;
+		LLSphere& other_sphere = (*map_itr).second;
+
+		if (!completely_linkable)
+		{
+			max_span = get_max_linkable_span(mBoundingSphere, other_sphere);
+	
+			F32 span = get_span(mBoundingSphere, other_sphere);
+
+			if (span > max_span)
+			{
+				++map_itr;
+				continue;
+			}
+		}
+
+		mDataMap[other_data] = other_sphere;
+		++link_count;
+
+		if (!mBoundingSphere.contains(other_sphere) )
+		{
+			computeBoundingSphere();
+		}
+
+		// remove from the other info
+		other_info.mDataMap.erase(map_itr++);
+	}
+
+	if (link_count > 0 && other_info.getPrimCount() > 0)
+	{
+		other_info.computeBoundingSphere();
+	}
+	return link_count;
+}
+
+// links any linkable elements of unlinked
+template < typename DATA_TYPE >
+S32 LLPrimLinkInfo< DATA_TYPE >::collapse(std::list< LLPrimLinkInfo< DATA_TYPE > > & unlinked)
+{ 
+	S32 link_count = 0;
+	bool linked_something = true;
+	while (linked_something)
+	{
+		linked_something = false;
+
+		typename std::list< LLPrimLinkInfo< DATA_TYPE > >::iterator this_itr = unlinked.begin();
+		typename std::list< LLPrimLinkInfo< DATA_TYPE > >::iterator other_itr = this_itr;
+		++other_itr;
+		while ( other_itr != unlinked.end() )
+			   
+		{
+			S32 merge_count = (*this_itr).merge(*other_itr);
+			if (merge_count > 0)
+			{
+				linked_something = true;
+				link_count += merge_count;
+			}
+			if (0 == (*other_itr).getPrimCount())
+			{
+				unlinked.erase(other_itr++);
+			}
+			else
+			{
+				++other_itr;
+			}
+		}
+	}
+	return link_count;
+}
+
+
+template < typename DATA_TYPE >
+void LLPrimLinkInfo< DATA_TYPE >::computeBoundingSphere()
+{ 
+	std::vector< LLSphere > sphere_list;
+	typename std::map< DATA_TYPE, LLSphere >::const_iterator map_itr;
+	for (map_itr = mDataMap.begin(); map_itr != mDataMap.end(); ++map_itr)
+	{
+		sphere_list.push_back(map_itr->second);
+	}
+	mBoundingSphere = LLSphere::getBoundingSphere(sphere_list);
+}
+
+
+#endif
+