1 /* 2 Bullet Continuous Collision Detection and Physics Library 3 Copyright (c) 2003-2009 Erwin Coumans http://bulletphysics.org 4 5 This software is provided 'as-is', without any express or implied warranty. 6 In no event will the authors be held liable for any damages arising from the use of this software. 7 Permission is granted to anyone to use this software for any purpose, 8 including commercial applications, and to alter it and redistribute it freely, 9 subject to the following restrictions: 10 11 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required. 12 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software. 13 3. This notice may not be removed or altered from any source distribution. 14 */ 15 16 #ifndef BT_HEIGHTFIELD_TERRAIN_SHAPE_H 17 #define BT_HEIGHTFIELD_TERRAIN_SHAPE_H 18 19 #include "btConcaveShape.h" 20 21 ///btHeightfieldTerrainShape simulates a 2D heightfield terrain 22 /** 23 The caller is responsible for maintaining the heightfield array; this 24 class does not make a copy. 25 26 The heightfield can be dynamic so long as the min/max height values 27 capture the extremes (heights must always be in that range). 28 29 The local origin of the heightfield is assumed to be the exact 30 center (as determined by width and length and height, with each 31 axis multiplied by the localScaling). 32 33 \b NOTE: be careful with coordinates. If you have a heightfield with a local 34 min height of -100m, and a max height of +500m, you may be tempted to place it 35 at the origin (0,0) and expect the heights in world coordinates to be 36 -100 to +500 meters. 37 Actually, the heights will be -300 to +300m, because bullet will re-center 38 the heightfield based on its AABB (which is determined by the min/max 39 heights). So keep in mind that once you create a btHeightfieldTerrainShape 40 object, the heights will be adjusted relative to the center of the AABB. This 41 is different to the behavior of many rendering engines, but is useful for 42 physics engines. 43 44 Most (but not all) rendering and heightfield libraries assume upAxis = 1 45 (that is, the y-axis is "up"). This class allows any of the 3 coordinates 46 to be "up". Make sure your choice of axis is consistent with your rendering 47 system. 48 49 The heightfield heights are determined from the data type used for the 50 heightfieldData array. 51 52 - PHY_UCHAR: height at a point is the uchar value at the 53 grid point, multipled by heightScale. uchar isn't recommended 54 because of its inability to deal with negative values, and 55 low resolution (8-bit). 56 57 - PHY_SHORT: height at a point is the short int value at that grid 58 point, multipled by heightScale. 59 60 - PHY_FLOAT: height at a point is the float value at that grid 61 point. heightScale is ignored when using the float heightfield 62 data type. 63 64 Whatever the caller specifies as minHeight and maxHeight will be honored. 65 The class will not inspect the heightfield to discover the actual minimum 66 or maximum heights. These values are used to determine the heightfield's 67 axis-aligned bounding box, multiplied by localScaling. 68 69 For usage and testing see the TerrainDemo. 70 */ 71 ATTRIBUTE_ALIGNED16(class) btHeightfieldTerrainShape : public btConcaveShape 72 { 73 protected: 74 btVector3 m_localAabbMin; 75 btVector3 m_localAabbMax; 76 btVector3 m_localOrigin; 77 78 ///terrain data 79 int m_heightStickWidth; 80 int m_heightStickLength; 81 btScalar m_minHeight; 82 btScalar m_maxHeight; 83 btScalar m_width; 84 btScalar m_length; 85 btScalar m_heightScale; 86 union 87 { 88 const unsigned char* m_heightfieldDataUnsignedChar; 89 const short* m_heightfieldDataShort; 90 const btScalar* m_heightfieldDataFloat; 91 const void* m_heightfieldDataUnknown; 92 }; 93 94 PHY_ScalarType m_heightDataType; 95 bool m_flipQuadEdges; 96 bool m_useDiamondSubdivision; 97 bool m_useZigzagSubdivision; 98 99 int m_upAxis; 100 101 btVector3 m_localScaling; 102 103 virtual btScalar getRawHeightFieldValue(int x,int y) const; 104 void quantizeWithClamp(int* out, const btVector3& point,int isMax) const; 105 void getVertex(int x,int y,btVector3& vertex) const; 106 107 108 109 /// protected initialization 110 /** 111 Handles the work of constructors so that public constructors can be 112 backwards-compatible without a lot of copy/paste. 113 */ 114 void initialize(int heightStickWidth, int heightStickLength, 115 const void* heightfieldData, btScalar heightScale, 116 btScalar minHeight, btScalar maxHeight, int upAxis, 117 PHY_ScalarType heightDataType, bool flipQuadEdges); 118 119 public: 120 121 BT_DECLARE_ALIGNED_ALLOCATOR(); 122 123 /// preferred constructor 124 /** 125 This constructor supports a range of heightfield 126 data types, and allows for a non-zero minimum height value. 127 heightScale is needed for any integer-based heightfield data types. 128 */ 129 btHeightfieldTerrainShape(int heightStickWidth,int heightStickLength, 130 const void* heightfieldData, btScalar heightScale, 131 btScalar minHeight, btScalar maxHeight, 132 int upAxis, PHY_ScalarType heightDataType, 133 bool flipQuadEdges); 134 135 /// legacy constructor 136 /** 137 The legacy constructor assumes the heightfield has a minimum height 138 of zero. Only unsigned char or floats are supported. For legacy 139 compatibility reasons, heightScale is calculated as maxHeight / 65535 140 (and is only used when useFloatData = false). 141 */ 142 btHeightfieldTerrainShape(int heightStickWidth,int heightStickLength,const void* heightfieldData, btScalar maxHeight,int upAxis,bool useFloatData,bool flipQuadEdges); 143 144 virtual ~btHeightfieldTerrainShape(); 145 146 147 void setUseDiamondSubdivision(bool useDiamondSubdivision=true) { m_useDiamondSubdivision = useDiamondSubdivision;} 148 149 ///could help compatibility with Ogre heightfields. See https://code.google.com/p/bullet/issues/detail?id=625 150 void setUseZigzagSubdivision(bool useZigzagSubdivision=true) { m_useZigzagSubdivision = useZigzagSubdivision;} 151 152 virtual void getAabb(const btTransform& t,btVector3& aabbMin,btVector3& aabbMax) const; 153 154 virtual void processAllTriangles(btTriangleCallback* callback,const btVector3& aabbMin,const btVector3& aabbMax) const; 155 156 virtual void calculateLocalInertia(btScalar mass,btVector3& inertia) const; 157 158 virtual void setLocalScaling(const btVector3& scaling); 159 160 virtual const btVector3& getLocalScaling() const; 161 162 //debugging 163 virtual const char* getName()const {return "HEIGHTFIELD";} 164 165 }; 166 167 #endif //BT_HEIGHTFIELD_TERRAIN_SHAPE_H 168
