bullet3/Demos/HeightFieldFluidDemo/BulletHfFluid/btHfFluid.h

#ifndef __HFFLUID_H
#define __HFFLUID_H

#include "BulletCollision/CollisionDispatch/btCollisionObject.h"
#include "BulletCollision/CollisionShapes/btTriangleCallback.h"

class btPersistentManifold;
class btManifoldResult;

// FIX AABB calculation for whole btHfFluid shape
// Fix flags and fill ratio
// -> Figure out the constants used in flags and fill ratio code
// Fix volume removal
// add buoyant convex vs. convex / concave
// add buoyant concave support (try bunny model)

class btHfFluid : public btCollisionObject
{
public:
	btHfFluid (btScalar gridCellWidth, int numNodesWidth, int numNodesLength);

	~btHfFluid ();

	void predictMotion(btScalar dt);

	/* Prep does some initial setup of the height field fluid.
	 * You should call this at initialization time.
	 */
	void prep ();
		
	static const btHfFluid*	upcast(const btCollisionObject* colObj)
	{
		if (colObj->getInternalType()==CO_HF_FLUID)
			return (const btHfFluid*)colObj;
		return 0;
	}
	static btHfFluid*			upcast(btCollisionObject* colObj)
	{
		if (colObj->getInternalType()==CO_HF_FLUID)
			return (btHfFluid*)colObj;
		return 0;
	}

	//
	// ::btCollisionObject
	//

	virtual void getAabb(btVector3& aabbMin,btVector3& aabbMax) const
	{
		aabbMin = m_aabbMin;
		aabbMax = m_aabbMax;
	}

	int getNumNodesWidth () const { return m_numNodesWidth; }
	int getNumNodesLength () const { return m_numNodesLength; }

	btScalar getGridCellWidth () const { return m_gridCellWidth; }
	btScalar widthPos (int i) const;
	btScalar lengthPos (int j) const;

	int arrayIndex (int i, int j) const;
	int arrayIndex (btScalar i, btScalar j) const;
	int arrayIndex (unsigned int i, unsigned int j) const;
	const btScalar* getHeightArray () const;
	const btScalar* getGroundArray () const;
	const btScalar* getEtaArray () const;
	const btScalar* getVelocityUArray () const;
	const btScalar* getVelocityVArray () const;
	const bool* getFlagsArray () const;

	void setFluidHeight (int x, int y, btScalar height);
	void setFluidHeight (int index, btScalar height);

	void addFluidHeight (int x, int y, btScalar height);
	void addDisplaced (int i, int j, btScalar r);

	void getAabbForColumn (int x, int y, btVector3& aabbMin, btVector3& aabbMax);

	btScalar* getHeightArray ();
	btScalar* getGroundArray ();
	btScalar* getEtaArray ();
	btScalar* getVelocityUArray ();
	btScalar* getVelocityVArray ();
	bool* getFlagsArray ();

	void foreachGroundTriangle(btTriangleCallback* callback,const btVector3& aabbMin,const btVector3& aabbMax);
	class btHfFluidColumnCallback 
	{
	public:
		btHfFluidColumnCallback () {}

		virtual ~btHfFluidColumnCallback () {}

		virtual bool processColumn (btHfFluid* fluid, int w, int l)
		{
			return true; // keep going
		}
	};

	void foreachFluidColumn (btHfFluidColumnCallback* callback, const btVector3& aabbMin, const btVector3& aabbMax);

	void foreachSurfaceTriangle (btTriangleCallback* callback, const btVector3& aabbMin, const btVector3& aabbMax);
protected:
	int m_numNodesWidth;
	int m_numNodesLength;

	btScalar m_gridCellWidth;
	btScalar m_gridWidth;
	btScalar m_gridLength;

	btScalar m_gridCellWidthInv;
	
	btVector3 m_aabbMin;
	btVector3 m_aabbMax;

	void setGridDimensions (btScalar gridCellWidth,
							int numNodesWidth, int numNodesLength);

	btScalar bilinearInterpolate (const btScalar* array, btScalar i, btScalar j);

	btScalar advect (const btScalar* array, btScalar i, btScalar j, btScalar di, btScalar dj, btScalar dt);

	void advectEta (btScalar dt);
	void updateHeight (btScalar dt);

	void advectVelocityU (btScalar dt);
	void advectVelocityV (btScalar dt);
	void updateVelocity (btScalar dt);

	void transferDisplaced (btScalar dt);

	void setReflectBoundaryLeft ();
	void setReflectBoundaryRight ();
	void setReflectBoundaryTop ();
	void setReflectBoundaryBottom ();

	void setAbsorbBoundaryLeft (btScalar dt);
	void setAbsorbBoundaryRight (btScalar dt);
	void setAbsorbBoundaryTop (btScalar dt);
	void setAbsorbBoundaryBottom (btScalar dt);

	void computeFlagsAndFillRatio ();
	btScalar computeHmin (int i, int j);
	btScalar computeHmax (int i, int j);
	btScalar computeEtaMax (int i, int j);

	void allocateArrays ();

	void debugTests ();

	btScalar* m_temp; // temp
	int m_heightIndex;
	btScalar* m_height[2];
	btScalar* m_ground;
	btScalar* m_eta; // height - ground
	btScalar* m_u[2];
	btScalar* m_v[2];
	int m_rIndex;
	btScalar* m_r[2];
	int m_velocityIndex;
	bool* m_flags;
	btScalar* m_fillRatio;

	// tweakables
	btScalar m_globalVelocityU;
	btScalar m_globalVelocityV;
	btScalar m_gravity;
	btScalar m_volumeDisplacementScale;
	btScalar m_horizontalVelocityScale;

	btScalar m_epsHeight;
	btScalar m_epsEta;
public:
	// You can enforce a global velocity at the surface of the fluid
	// default: 0.0 and 0.0
	void setGlobaVelocity (btScalar globalVelocityU, btScalar globalVelocityV);
	void getGlobalVelocity (btScalar& globalVelocityU, btScalar& globalVelocityV) const;

	// Control force of gravity, should match physics world
	// default: -10.0
	void setGravity (btScalar gravity);
	btScalar getGravity () const;

	// When a body is submerged into the fluid, the displaced fluid
	// is spread to adjacent cells. You can control the percentage of this
	// by setting this value between 0.0 and 1.0
	// default: 0.5
	void setVolumeDisplacementScale (btScalar volumeDisplacementScale);
	btScalar getVolumeDisplacementScale () const;

	// The horizontal velocity of the fluid can influence bodies submerged
	// in the fluid. You can control how much influence by setting this
	// between 0.0 and 1.0
	// default: 0.5
	void setHorizontalVelocityScale (btScalar horizontalVelocityScale);
	btScalar getHorizontalVelocityScale () const;
};

class btRigidBody;
class btIDebugDraw;
class btHfFluidBuoyantConvexShape;

class btHfFluidColumnRigidBodyCallback : public btHfFluid::btHfFluidColumnCallback
{
protected:
	btRigidBody* m_rigidBody;
	btHfFluidBuoyantConvexShape* m_buoyantShape;
	btIDebugDraw* m_debugDraw;
	int m_numVoxels;
	btVector3 m_voxelPositionsXformed[32*32*32];
	bool m_voxelSubmerged[32*32*32];
	btVector3 m_aabbMin;
	btVector3 m_aabbMax;
	btScalar m_volume;
	btScalar m_density;
	btScalar m_floatyness;
public:
	btHfFluidColumnRigidBodyCallback (btRigidBody* rigidBody, btIDebugDraw* debugDraw, btScalar density, btScalar floatyness);
	bool processColumn (btHfFluid* fluid, int w, int l);
	btScalar getVolume () const { return m_volume; }
};

#endif