168 lines
6.5 KiB
C
168 lines
6.5 KiB
C
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/*
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Bullet Continuous Collision Detection and Physics Library
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Copyright (c) 2003-2009 Erwin Coumans http://bulletphysics.org
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This software is provided 'as-is', without any express or implied warranty.
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In no event will the authors be held liable for any damages arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it freely,
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subject to the following restrictions:
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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.
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2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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#ifndef BT_HEIGHTFIELD_TERRAIN_SHAPE_H
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#define BT_HEIGHTFIELD_TERRAIN_SHAPE_H
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#include "btConcaveShape.h"
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///btHeightfieldTerrainShape simulates a 2D heightfield terrain
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/**
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The caller is responsible for maintaining the heightfield array; this
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class does not make a copy.
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The heightfield can be dynamic so long as the min/max height values
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capture the extremes (heights must always be in that range).
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The local origin of the heightfield is assumed to be the exact
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center (as determined by width and length and height, with each
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axis multiplied by the localScaling).
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\b NOTE: be careful with coordinates. If you have a heightfield with a local
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min height of -100m, and a max height of +500m, you may be tempted to place it
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at the origin (0,0) and expect the heights in world coordinates to be
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-100 to +500 meters.
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Actually, the heights will be -300 to +300m, because bullet will re-center
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the heightfield based on its AABB (which is determined by the min/max
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heights). So keep in mind that once you create a btHeightfieldTerrainShape
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object, the heights will be adjusted relative to the center of the AABB. This
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is different to the behavior of many rendering engines, but is useful for
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physics engines.
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Most (but not all) rendering and heightfield libraries assume upAxis = 1
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(that is, the y-axis is "up"). This class allows any of the 3 coordinates
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to be "up". Make sure your choice of axis is consistent with your rendering
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system.
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The heightfield heights are determined from the data type used for the
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heightfieldData array.
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- PHY_UCHAR: height at a point is the uchar value at the
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grid point, multipled by heightScale. uchar isn't recommended
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because of its inability to deal with negative values, and
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low resolution (8-bit).
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- PHY_SHORT: height at a point is the short int value at that grid
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point, multipled by heightScale.
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- PHY_FLOAT: height at a point is the float value at that grid
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point. heightScale is ignored when using the float heightfield
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data type.
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Whatever the caller specifies as minHeight and maxHeight will be honored.
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The class will not inspect the heightfield to discover the actual minimum
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or maximum heights. These values are used to determine the heightfield's
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axis-aligned bounding box, multiplied by localScaling.
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For usage and testing see the TerrainDemo.
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*/
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ATTRIBUTE_ALIGNED16(class) btHeightfieldTerrainShape : public btConcaveShape
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{
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protected:
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btVector3 m_localAabbMin;
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btVector3 m_localAabbMax;
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btVector3 m_localOrigin;
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///terrain data
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int m_heightStickWidth;
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int m_heightStickLength;
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btScalar m_minHeight;
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btScalar m_maxHeight;
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btScalar m_width;
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btScalar m_length;
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btScalar m_heightScale;
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union
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{
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const unsigned char* m_heightfieldDataUnsignedChar;
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const short* m_heightfieldDataShort;
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const btScalar* m_heightfieldDataFloat;
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const void* m_heightfieldDataUnknown;
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};
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PHY_ScalarType m_heightDataType;
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bool m_flipQuadEdges;
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bool m_useDiamondSubdivision;
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bool m_useZigzagSubdivision;
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int m_upAxis;
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btVector3 m_localScaling;
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virtual btScalar getRawHeightFieldValue(int x,int y) const;
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void quantizeWithClamp(int* out, const btVector3& point,int isMax) const;
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void getVertex(int x,int y,btVector3& vertex) const;
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/// protected initialization
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/**
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Handles the work of constructors so that public constructors can be
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backwards-compatible without a lot of copy/paste.
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*/
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void initialize(int heightStickWidth, int heightStickLength,
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const void* heightfieldData, btScalar heightScale,
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btScalar minHeight, btScalar maxHeight, int upAxis,
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PHY_ScalarType heightDataType, bool flipQuadEdges);
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public:
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BT_DECLARE_ALIGNED_ALLOCATOR();
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/// preferred constructor
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/**
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This constructor supports a range of heightfield
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data types, and allows for a non-zero minimum height value.
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heightScale is needed for any integer-based heightfield data types.
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*/
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btHeightfieldTerrainShape(int heightStickWidth,int heightStickLength,
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const void* heightfieldData, btScalar heightScale,
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btScalar minHeight, btScalar maxHeight,
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int upAxis, PHY_ScalarType heightDataType,
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bool flipQuadEdges);
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/// legacy constructor
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/**
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The legacy constructor assumes the heightfield has a minimum height
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of zero. Only unsigned char or floats are supported. For legacy
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compatibility reasons, heightScale is calculated as maxHeight / 65535
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(and is only used when useFloatData = false).
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*/
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btHeightfieldTerrainShape(int heightStickWidth,int heightStickLength,const void* heightfieldData, btScalar maxHeight,int upAxis,bool useFloatData,bool flipQuadEdges);
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virtual ~btHeightfieldTerrainShape();
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void setUseDiamondSubdivision(bool useDiamondSubdivision=true) { m_useDiamondSubdivision = useDiamondSubdivision;}
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///could help compatibility with Ogre heightfields. See https://code.google.com/p/bullet/issues/detail?id=625
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void setUseZigzagSubdivision(bool useZigzagSubdivision=true) { m_useZigzagSubdivision = useZigzagSubdivision;}
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virtual void getAabb(const btTransform& t,btVector3& aabbMin,btVector3& aabbMax) const;
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virtual void processAllTriangles(btTriangleCallback* callback,const btVector3& aabbMin,const btVector3& aabbMax) const;
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virtual void calculateLocalInertia(btScalar mass,btVector3& inertia) const;
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virtual void setLocalScaling(const btVector3& scaling);
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virtual const btVector3& getLocalScaling() const;
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//debugging
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virtual const char* getName()const {return "HEIGHTFIELD";}
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};
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#endif //BT_HEIGHTFIELD_TERRAIN_SHAPE_H
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