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include/framework/bih/bih.h

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+/* -----------------------------------------------------------------------------
+	GSFramework
+	Copyright 2001-2013 Emmanuel Julien. All Rights Reserved.
+----------------------------------------------------------------------------- */
+
+
+#ifndef	__NBIH__
+#define	__NBIH__
+
+
+		#include "geometry/bounding_box.h"
+		#include "container/narray.h"
+		#include "memory/nauto_ptr.h"
+
+
+namespace GS {
+	namespace BIH {
+
+// Bounding interval hierarchy node.
+struct	Node
+{
+		char			axis;				///< @TODO: Packed bitfield!
+		void			*p;					///< Pointer to child nodes or index array.
+
+		union
+		{
+			uint		count;				///< Index count in leaf.
+			float		split[2];			///< Split planes.
+		};
+
+		Node() : axis(3), p(0) {}
+		~Node();
+};
+
+struct	StackEntry
+{
+		Node			*node;
+		float			tmin, tmax;
+};
+
+//
+struct	Trace
+{
+		StackEntry		stack[65];
+		uint			stack_pos;
+
+		bool			want_closest;
+
+		bool			has_i;				///< Do we have an intersection.
+		float			i_t;				///< Distance to intersection from ray's origin.
+		Vector4			s;					///< Ray origin.
+		Vector4			d;					///< Ray direction.
+
+		uint			node_visited;		///< Number of nodes visited.
+
+		Trace(bool closest = true) : want_closest(closest), has_i(false) {}
+};
+
+/*!
+	@short	Bounding interval hierarchy.
+
+	This is a fully generic bounding interval hierarchy implementation.
+	In order to use this structure on a custom set of data you need to derive
+	from this class and provide the implementation for the TraceLeaf method.
+
+	In order to build the structure you simply provide a list of volumes to the
+	build() methods.
+
+	@author	Emmanuel Julien (ejulien@gsworks.fr)
+*/
+class	Tree
+{
+protected:
+
+		/// Minimum leaf volume count.
+		uint			min_leaf_vcount;
+
+		MinMax			minmax;				///< Hierarchy bounding box.
+		AutoPtr <Node>	root;				///< Hierarchy root node.
+
+		Array <uint> sarray;				///< Index array.
+
+		uint			node_count;
+		uint			leaf_count;
+		uint			depth;
+/*!
+	@name	Trace functions.
+	@{
+*/
+		/// Trace a leaf.
+virtual	void			TraceLeaf(Node *leaf, float tmin, float tmax, Trace &trace, void *parm = 0) = 0;
+		/// Trace a node.
+		void			TraceNode(Node *node, float tmin, float tmax, Trace &trace);
+/// @}
+
+/*!
+	@name	Intersection functions.
+	@{
+*/
+		/// Intersect a node.
+		uint			IntersectNode(Node *node, MinMax &sub_mm, uint *index_array, uint max_index);
+/// @}
+
+/*!
+	@name	Build functions.
+	@{
+*/
+		/// Create a leaf.
+		void			MakeNodeLeaf(Node *node, uint count, uint *sarray, MinMax *varray);
+		/// Perform a node split.
+		void			DoNodeSplit(MinMax &minmax, uint count, uint *sarray, MinMax *varray, uint &pivot, Node *node, uint &split_axis);
+		/// Split an index list of volumes.
+		bool			Split(MinMax &minmax, uint count, uint *sarray, MinMax *varray, Node *node, uint depth);
+
+		/// Build hierarchy from a set of input volumes.
+virtual	bool			Build(uint volume_count, MinMax *varray);
+/// @}
+
+public:
+
+		/// Intersect tree with an axis aligned bounding box.
+		uint			Intersect(MinMax &minmax, uint *index_array, uint max_index);
+		/*
+			@short	Raytrace hierarchy.
+			@note	Ray direction must be normalized.
+		*/
+virtual	void			Raytrace(Trace &trace, const Vector4 &s, const Vector4 &d, float l = -1.f, void *parm = 0);
+
+		/// Delete hierarchy.
+virtual	void			Free();
+
+		Tree();
+virtual	~Tree();
+};
+
+	} // BIH
+} // GS
+
+
+#endif	// __NBIH__