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#ifndef BT_HEIGHTFIELD_TERRAIN_SHAPE_H

#define BT_HEIGHTFIELD_TERRAIN_SHAPE_H

#include "btConcaveShape.h"

///btHeightfieldTerrainShape simulates a 2D heightfield terrain

/**

The caller is responsible for maintaining the heightfield array; this

class does not make a copy.

The heightfield can be dynamic so long as the min/max height values

capture the extremes (heights must always be in that range).

The local origin of the heightfield is assumed to be the exact

center (as determined by width and length and height, with each

axis multiplied by the localScaling).

\b NOTE: be careful with coordinates. If you have a heightfield with a local

min height of -100m, and a max height of +500m, you may be tempted to place it

at the origin (0,0) and expect the heights in world coordinates to be

-100 to +500 meters.

Actually, the heights will be -300 to +300m, because bullet will re-center

the heightfield based on its AABB (which is determined by the min/max

heights). So keep in mind that once you create a btHeightfieldTerrainShape

object, the heights will be adjusted relative to the center of the AABB. This

is different to the behavior of many rendering engines, but is useful for

physics engines.

Most (but not all) rendering and heightfield libraries assume upAxis = 1

(that is, the y-axis is "up"). This class allows any of the 3 coordinates

to be "up". Make sure your choice of axis is consistent with your rendering

system.

The heightfield heights are determined from the data type used for the

heightfieldData array.

- PHY_UCHAR: height at a point is the uchar value at the

grid point, multipled by heightScale. uchar isn't recommended

because of its inability to deal with negative values, and

low resolution (8-bit).

- PHY_SHORT: height at a point is the short int value at that grid

point, multipled by heightScale.

- PHY_FLOAT: height at a point is the float value at that grid

point. heightScale is ignored when using the float heightfield

data type.

Whatever the caller specifies as minHeight and maxHeight will be honored.

The class will not inspect the heightfield to discover the actual minimum

or maximum heights. These values are used to determine the heightfield's

axis-aligned bounding box, multiplied by localScaling.

For usage and testing see the TerrainDemo.

class btHeightfieldTerrainShape : public btConcaveShape

{

protected:

btVector3 m_localAabbMin;

btVector3 m_localAabbMax;

btVector3 m_localOrigin;

///terrain data

int m_heightStickWidth;

int m_heightStickLength;

btScalar m_minHeight;

btScalar m_maxHeight;

btScalar m_width;

btScalar m_length;

btScalar m_heightScale;

union

{

unsigned char* m_heightfieldDataUnsignedChar;

short* m_heightfieldDataShort;

btScalar* m_heightfieldDataFloat;

void* m_heightfieldDataUnknown;

};

PHY_ScalarType m_heightDataType;

bool m_flipQuadEdges;

bool m_useDiamondSubdivision;

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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void initialize(int heightStickWidth, int heightStickLength,

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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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/// 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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btHeightfieldTerrainShape(int heightStickWidth,int heightStickLength,

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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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btHeightfieldTerrainShape(int heightStickWidth,int heightStickLength,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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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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