GAS_Elasticity.h

Go to the documentation of this file.

/*
 * 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.
 *
 * 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 <GA/GA_Handle.h>
#include <GA/GA_Types.h>

#include <UT/UT_Map.h>
#include <UT/UT_ThreadedAlgorithm.h>
#include <UT/UT_ValArray.h>

class GU_Detail;
class GAS_SPH;
class UT_String;

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);
                        ~GAS_Elasticity() override;

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

    THREADED_METHOD4(GAS_Elasticity, shouldMultiThread(), applySprings,
                                GU_Detail *, gdp, 
                                const GAS_SPH &, sph,
                                fpreal, elasticityconst,
                                SIM_Time, timestep)
    void                 applySpringsPartial(GU_Detail *gdp,
                                const GAS_SPH &sph,
                                fpreal elasticityconst, SIM_Time timestep,
                                const UT_JobInfo &info);

private:
    bool                 myUseID;

    /// This function reads spring length information from the
    /// springlengths and springindices point attributes.
    void                 getSprings(GA_Offset ptoff,
                                    const GA_ROHandleR &lengthattrib,
                                    const GA_ROHandleI &indexattrib,
                                    UT_FloatArray &weightmap,
                                    UT_IntArray &indices,
                                    const UT_Map<int,int> &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