GAS/GAS_AdjustElasticity.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_AdjustElasticity.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).  The purpose of
 *              this particular node is to dynamically adjust the
 *              lengths of springs between fluid particles.
 *
 */

#ifndef __GAS_AdjustElasticity__
#define __GAS_AdjustElasticity__

#include "GAS_API.h"

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

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

#include <UT/UT_ThreadedAlgorithm.h>

class GAS_API GAS_AdjustElasticity : public GAS_SubSolver
{
public:
    GET_DATA_FUNC_S(GAS_NAME_GEOMETRY,  GeometryName);
    GET_DATA_FUNC_B("doelasticity",     DoElasticity);
    GET_DATA_FUNC_F("plasticityconst",  PlasticityConstant);
    GET_DATA_FUNC_F("yieldratio",       YieldRatio);
    GET_DATA_FUNC_B("clampsprings",     ClampNumSprings);
    GET_DATA_FUNC_I("maxsprings",       MaxSprings);
    GET_DATA_FUNC_B("useid",            UseID);

    bool                 shouldMultiThread() { return true; }

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

    /// Adds and removes springs between particles as necessary,
    /// and also dynamically adjusts the lengths of springs
    /// between particles.
    virtual bool         solveGasSubclass(SIM_Engine &engine,
                                    SIM_Object *obj,
                                    SIM_Time time,
                                    SIM_Time timestep);

    THREADED_METHOD5(GAS_AdjustElasticity, shouldMultiThread(),
                                    adjustSprings, GU_Detail *, gdp,
                                    GAS_SPH &, sph,
                                    fpreal, yieldratio,
                                    fpreal, plasticityconstant,
                                    SIM_Time, timestep)
    void                 adjustSpringsPartial(GU_Detail *gdp,
                                    GAS_SPH &sph,
                                    fpreal yieldratio,
                                    fpreal plasticity,
                                    SIM_Time timestep,
                                    const UT_JobInfo &info);

private:
    bool                 myUseID;

    /// A similar function to the one above, but this writes
    /// the spring information in to attribute handles.
    void                 setSprings(GEO_AttributeHandle &lengthgah,
                                    GEO_AttributeHandle &indexgah,
                                    const UT_FloatArray &lengthlist,
                                    const UT_IntArray &idxlist,
                                    fpreal h, int initiallength);


    /// A similar function to the one above that reads the
    /// information from attribute handles.  We assume that
    /// the point has already been set in the handle.
    void                 getSprings(GEO_AttributeHandle &lengthgah,
                                    GEO_AttributeHandle &indexgah,
                                    UT_FloatArray &weightmap,
                                    UT_IntArray &indices,
                                    const UT_HashTable &weighthash);

    /// Adjusts the size of the spring attributes, if necessary.
    void                 resizeSpringAttributes(GU_Detail *gdp, GAS_SPH &sph);

    /// Queries the sph structure at each point to determine the
    /// number of entries required in the spring attributes.
    int                  getAttribSize(GU_Detail *gdp, GAS_SPH &sph);

    /// 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);    

    /// Reduce the given point list to the given maximum size.
    /// The points closest to the reference point will be kept.
    void                 sortAndCullPoints(GEO_Point *pt,
                                UT_PtrArray<GEO_Point *> &ptlist,
                                int newmax) const;

    static const SIM_DopDescription     *getDopDescription();

    DECLARE_STANDARD_GETCASTTOTYPE();
    DECLARE_DATAFACTORY(GAS_AdjustElasticity,
                        GAS_SubSolver,
                        "Gas Adjust Elasticity",
                        getDopDescription());
};

#endif

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