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Torque/SDK/engine/util/quadTreeTracer.h

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+//-----------------------------------------------------------------------------
+// Torque Shader Engine
+// Copyright (C) GarageGames.com, Inc.
+//-----------------------------------------------------------------------------
+
+#ifndef _QUADTREETRACER_H_
+#define _QUADTREETRACER_H_
+
+#include "platform/platform.h"
+#include "math/mPoint.h"
+#include "sim/sceneObject.h"
+
+/// Helper class to perform a fast, recursive ray cast against a set of
+/// hierarchical bounding boxes.
+///
+/// This class assumes that it is working on a unit quadtree (ie, one that
+/// extends from 0..1 in the XY dimensions. Z scale is unaffected).
+///
+/// Node indexing is done TGE Terrain style - 0 is the largest level of the
+/// quadtree, while coordinates are always in the full range of the quadtree
+/// (in a 6 deep tree, 0..63, for instance). This allows the quadtree descent
+/// to be very fast!
+class QuadTreeTracer
+{
+protected:
+
+   struct StackNode
+   {
+      Point2I squarePos;
+      U32     level;
+   };
+
+   struct RayStackNode : StackNode
+   {
+      F32     startT;
+      F32     endT;
+   };
+
+   U32 mTreeDepth;
+
+   QuadTreeTracer(U32 treeDepth)
+      : mTreeDepth(treeDepth)
+   {
+   }
+
+   /// Children better implement these! They return min/max height bounds
+   /// of the specified square.
+   virtual const F32 getSquareMin(const U32 &level, const Point2I &pos) const = 0;
+   virtual const F32 getSquareMax(const U32 &level, const Point2I &pos) const = 0;
+
+   /// And this does checks on leaf nodes.
+   virtual bool castLeafRay(const Point2I pos, const Point3F &start, const Point3F &end, const F32 &startT, const F32 &endT, RayInfo *info) = 0;
+
+   /// Helper function to calculate intercepts.
+   inline const F32 calcIntercept(const F32 vStart, const F32 invDeltaV, const F32 intercept) const
+   {
+      return (intercept - vStart) * invDeltaV;
+   }
+
+public:
+
+   /// Size of a quadtree of depth.
+   static inline const U32 getNodeCount(const U32 depth)
+   {
+      return 0x55555555 & ((1 << depth*2) - 1);
+   }
+
+   /// Index of a node at given position in a quadtree.
+   static inline const U32 getNodeIndex(const U32 level, const Point2I pos)
+   {
+      //AssertFatal(level < mTreeDepth, "QuadTreeTracer::getNodeIndex - out of range level!)
+      AssertFatal(pos.x < BIT(level) && pos.x >= 0 , "QuadTreeTracer::getNodeIndex - out of range x for level!");
+      AssertFatal(pos.y < BIT(level) && pos.y >= 0 , "QuadTreeTracer::getNodeIndex - out of range y for level!");
+
+      const U32 base = getNodeCount(level);
+      return base + (pos.x << level) + pos.y;
+   }
+
+   /// Cast a ray against a quadtree of hierarchical bounding boxes.
+   ///
+   /// This method assumes the quadtree extends from (0..1) along the
+   /// X and Y axes. Z is unscaled. You may need to adjust the points
+   /// you pass into this method to get the proper results.
+   bool castRay(const Point3F &start, const Point3F &end, RayInfo *info);
+};
+
+#endif