GAS/GAS_Elasticity.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * Produced by:
 *      Jeff Chadwick
 *      Side Effects Software Inc
 *      123 Front Street West, Suite 1401
 *      Toronto, Ontario
 *      Canada   M5J 2M2
 *      416-504-9876
 *
 * NAME:        GAS_Elasticity.h ( GAS Library, C++)
 *
 * COMMENTS:    This node is intended to simulate elastic forces
 *              within a particle-based fluid using a simple
 *              spring setup.  This is similar to the technique
 *              described in "Particle-based Viscoelastic Fluid
 *              Simultion" (see paper repository).
 *
 */

#ifndef __GAS_Elasticity__
#define __GAS_Elasticity__

#include "GAS_API.h"

#include "GAS_SubSolver.h"
#include "GAS_Utils.h"

#include <UT/UT_PtrArray.h>

#include <UT/UT_ThreadedAlgorithm.h>

class GEO_AttributeHandle;
class GU_Point;
class GU_Detail;
class GAS_SPH;
class UT_IntArray;
class UT_FloatArray;
class UT_String;
class UT_HashTable;

class GAS_API GAS_Elasticity : public GAS_SubSolver
{
public:
    GET_DATA_FUNC_S(GAS_NAME_GEOMETRY,  GeometryName);
    GET_DATA_FUNC_F("elasticityconst",  ElasticityConstant);
    GET_DATA_FUNC_B("doelasticity",     DoElasticity);
    GET_DATA_FUNC_B("computev",         ComputeVelocity);
    GET_DATA_FUNC_B("useid",            UseID);

    bool                 shouldMultiThread() { return true; }

protected:
    explicit             GAS_Elasticity(const SIM_DataFactory *factory);
    virtual             ~GAS_Elasticity();

    /// Computes pairwise elastic forces between particles in the
    /// given particle field and either adjusts the velocity
    /// directly, or just adds to the force attribute.
    virtual bool         solveGasSubclass(SIM_Engine &engine,
                                    SIM_Object *obj,
                                    SIM_Time time,
                                    SIM_Time timestep);

    THREADED_METHOD3(GAS_Elasticity, shouldMultiThread(), applySprings,
                                GU_Detail *, gdp, fpreal, elasticityconst,
                                SIM_Time, timestep)
    void                 applySpringsPartial(GU_Detail *gdp,
                                fpreal elasticityconst, SIM_Time timestep,
                                const UT_JobInfo &info);

    THREADED_METHOD2(GAS_Elasticity, shouldMultiThread(), applyForces,
                                GU_Detail *, gdp, SIM_Time, timestep)
    void                 applyForcesPartial(GU_Detail *gdp, SIM_Time timestep,
                                const UT_JobInfo &info);

    THREADED_METHOD1(GAS_Elasticity, shouldMultiThread(), clearForces,
                                GU_Detail *, gdp)
    void                 clearForcesPartial(GU_Detail *gdp,
                                const UT_JobInfo &info);

private:
    bool                 myUseID;

    /// This function reads spring length information from the
    /// springlengths and springindices point attributes.
    void                 getSprings(GEO_AttributeHandle &lengthgah,
                                    GEO_AttributeHandle &indexgah,
                                    UT_FloatArray &weightmap,
                                    UT_IntArray &indices,
                                    const UT_HashTable &weighthash);

    /// Creates a float attribute of the given length to store
    /// spring lengths.
    void                 createLengthAttrib(GU_Detail *gdp, int size);

    /// Creates an int attribute of the given length to store
    /// spring indices.
    void                 createIndexAttrib(GU_Detail *gdp, int size);

    /// Grow these attributes to the given size.
    void                 growLengthAttrib(GU_Detail *gdp,
                                    int initialsize, int finalsize);    
    void                 growIndexAttrib(GU_Detail *gdp,
                                    int initialsize, int finalsize);    

    static const SIM_DopDescription     *getDopDescription();

    DECLARE_STANDARD_GETCASTTOTYPE();
    DECLARE_DATAFACTORY(GAS_Elasticity,
                        GAS_SubSolver,
                        "Gas Elasticity",
                        getDopDescription());

};

#endif

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