quadTreeTracer.h

Engine/source/util/quadTreeTracer.h

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  1
  2//-----------------------------------------------------------------------------
  3// Copyright (c) 2012 GarageGames, LLC
  4//
  5// Permission is hereby granted, free of charge, to any person obtaining a copy
  6// of this software and associated documentation files (the "Software"), to
  7// deal in the Software without restriction, including without limitation the
  8// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
  9// sell copies of the Software, and to permit persons to whom the Software is
 10// furnished to do so, subject to the following conditions:
 11//
 12// The above copyright notice and this permission notice shall be included in
 13// all copies or substantial portions of the Software.
 14//
 15// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 16// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 17// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 18// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 19// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 20// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 21// IN THE SOFTWARE.
 22//-----------------------------------------------------------------------------
 23
 24#ifndef _QUADTREETRACER_H_
 25#define _QUADTREETRACER_H_
 26
 27#include "platform/platform.h"
 28#include "math/mPoint3.h"
 29#include "scene/sceneObject.h"
 30
 31/// Helper class to perform a fast, recursive ray cast against a set of
 32/// hierarchical bounding boxes.
 33///
 34/// This class assumes that it is working on a unit quadtree (ie, one that
 35/// extends from 0..1 in the XY dimensions. Z scale is unaffected).
 36///
 37/// Node indexing is done TGE Terrain style - 0 is the largest level of the
 38/// quadtree, while coordinates are always in the full range of the quadtree
 39/// (in a 6 deep tree, 0..63, for instance). This allows the quadtree descent
 40/// to be very fast!
 41class QuadTreeTracer
 42{
 43protected:
 44
 45   struct StackNode
 46   {
 47      Point2I squarePos;
 48      U32     level;
 49   };
 50
 51   struct RayStackNode : StackNode
 52   {
 53      F32     startT;
 54      F32     endT;
 55   };
 56
 57   U32 mTreeDepth;
 58
 59   QuadTreeTracer(U32 treeDepth)
 60      : mTreeDepth(treeDepth)
 61   {
 62   }
 63
 64   /// Children better implement these! They return min/max height bounds
 65   /// of the specified square.
 66   virtual const F32 getSquareMin(const U32 &level, const Point2I &pos) const = 0;
 67   virtual const F32 getSquareMax(const U32 &level, const Point2I &pos) const = 0;
 68
 69   /// And this does checks on leaf nodes.
 70   virtual bool castLeafRay(const Point2I pos, const Point3F &start, const Point3F &end, const F32 &startT, const F32 &endT, RayInfo *info) = 0;
 71
 72   /// Helper function to calculate intercepts.
 73   inline const F32 calcIntercept(const F32 vStart, const F32 invDeltaV, const F32 intercept) const
 74   {
 75      return (intercept - vStart) * invDeltaV;
 76   }
 77
 78public:
 79
 80   /// Size of a quadtree of depth.
 81   static inline const U32 getNodeCount(const U32 depth)
 82   {
 83      return 0x55555555 & ((1 << depth*2) - 1);
 84   }
 85
 86   /// Index of a node at given position in a quadtree.
 87   static inline const U32 getNodeIndex(const U32 level, const Point2I pos)
 88   {
 89      //AssertFatal(level < mTreeDepth, "QuadTreeTracer::getNodeIndex - out of range level!)
 90      AssertFatal(pos.x < BIT(level) && pos.x >= 0 , "QuadTreeTracer::getNodeIndex - out of range x for level!");
 91      AssertFatal(pos.y < BIT(level) && pos.y >= 0 , "QuadTreeTracer::getNodeIndex - out of range y for level!");
 92
 93      const U32 base = getNodeCount(level);
 94      return base + (pos.x << level) + pos.y;
 95   }
 96
 97   /// Cast a ray against a quadtree of hierarchical bounding boxes.
 98   ///
 99   /// This method assumes the quadtree extends from (0..1) along the
100   /// X and Y axes. Z is unscaled. You may need to adjust the points
101   /// you pass into this method to get the proper results.
102   bool castRay(const Point3F &start, const Point3F &end, RayInfo *info);
103};
104
105#endif
106