SIM_ForceField.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.
 *
 */

#ifndef __SIM_ForceField_h__
#define __SIM_ForceField_h__

#include "SIM_API.h"
#include "SIM_Force.h"
#include "SIM_OptionsUser.h"
#include <UT/UT_Matrix.h>
#include <GA/GA_Handle.h>

/// This is an implementation of the SIM_Force interface. This implementation
/// calculates the interpolated value from a point cloud with force and
/// torque attributes attached to it.
class SIM_API SIM_ForceField : public SIM_Force,
                               public SIM_OptionsUser
{
public:
    /// The name of the point attribute holding the force values.
    GETSET_DATA_FUNCS_S(SIM_NAME_FORCEATTRIBNAME, ForceAttribName);
    /// Scale the calculated force value.
    GETSET_DATA_FUNCS_F(SIM_NAME_FORCESCALE, ForceScale);
    /// The name of the point attribute holding the torque values.
    GETSET_DATA_FUNCS_S(SIM_NAME_TORQUEATTRIBNAME, TorqueAttribName);
    /// Scale the calculated torque value.
    GETSET_DATA_FUNCS_F(SIM_NAME_TORQUESCALE, TorqueScale);
    /// Determines whether or not there is a maximum distance to check.
    GETSET_DATA_FUNCS_B(SIM_NAME_USEMAXDISTANCE, UseMaxDistance);
    /// The maximum distance we are allowed to search for a point.
    GETSET_DATA_FUNCS_F(SIM_NAME_MAXDISTANCE, MaxDistance);
    /// Whether to treat the force as a wind or a force.
    GETSET_DATA_FUNCS_B(SIM_NAME_TREATASWIND, TreatAsWind);
    /// Whether to sample by point, circle, or sphere.
    GETSET_DATA_FUNCS_I(SIM_NAME_SAMPLEMODE, SampleMode);

protected:
    explicit             SIM_ForceField(const SIM_DataFactory *factory);
                        ~SIM_ForceField() override;

    /// Returns the force and torque on a point. The returned values are
    /// exact copies of the force and torque attributes. The
    /// getForceOnCircleSubclass() and getForceOnSphereSubclass()
    /// functions use the default implementations which scale the point
    /// force by the area or volume of the circle or sphere. This means
    /// that regardless of the size of samples used to quantize an object,
    /// the total force on the object should remain roughly constant.
    void                 getForceSubclass(
                                        const SIM_Object &object,
                                        const UT_Vector3 &position,
                                        const UT_Vector3 &velocity,
                                        const UT_Vector3 &angvel,
                                        const fpreal mass,
                                        UT_Vector3 &force,
                                        UT_Vector3 &torque) const override;
    SIM_ForceResolver   *getForceResolverSubclass(
                                    const SIM_Object &object) const override;

    void                 getForceOnCircleSubclass(
                                        const SIM_Object &object,
                                        const UT_Vector3 &position,
                                        const UT_Vector3 &normal,
                                        const fpreal radius,
                                        const UT_Vector3 &velocity,
                                        const UT_Vector3 &angvel,
                                        const fpreal mass,
                                        UT_Vector3 &force,
                                        UT_Vector3 &torque) const override;

    void                 getForceJacobianSubclass(
                                        const SIM_Object &object,
                                        const UT_Vector3 &position,
                                        const UT_Vector3 &velocity,
                                        const UT_Vector3 &angvel,
                                        const fpreal mass,
                                        UT_Matrix &dFdX,
                                        UT_Matrix &dFdV) const override;

    /// We want to use area sampling if treat as wind is on.
    SIM_ForceSample      getOptimalForceSamplingSubclass() const override;
    
    /// Override this to return a SIM_GuideShared so we only have to draw
    /// our guide geometry once regardless of how many objects we are
    /// attached to.
    SIM_Guide           *createGuideObjectSubclass() const override;
    /// Build guide geometry by copying the points from the source geometry,
    /// and adding lines to represent the force and torque vectors.
    void                 buildGuideGeometrySubclass(
                                        const SIM_RootData &root,
                                        const SIM_Options &options,
                                        const GU_DetailHandle &gdh,
                                        UT_DMatrix4 *xform,
                                        const SIM_Time &t) const override;

private:
    void                 createVectorGuide(GU_Detail *gdp,
                                           const UT_Vector3 &pos,
                                           UT_Vector3 f,
                                           fpreal scale,
                                           const GA_RWHandleV3 &colour_attrib,
                                           const UT_Vector3 &colour) const;
    void                 getAttribOffsets(const GU_Detail *gdp,
                                          const char *forceattribname,
                                          GA_ROHandleV3 &force_attrib,
                                          const char *torqueattribname,
                                          GA_ROHandleV3 &torque_attrib) const;
    void                 getPositionTransform(UT_DMatrix4 &xform) const;
    void                 getPositionInverseTransform(UT_DMatrix4 &ixform) const;

    static const SIM_DopDescription     *getForceFieldDopDescription();

    DECLARE_STANDARD_GETCASTTOTYPE();
    DECLARE_DATAFACTORY(SIM_ForceField,
                        SIM_Force,
                        "Field Force",
                        getForceFieldDopDescription());

    friend class SIM_ForceResolverField;
};

#endif