SIM/SIM_ForceDrag.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:
 *      Side Effects Software Inc.
 *      477 Richmond Street West, Suite 1001
 *      Toronto, Ontario
 *      Canada   M5V 3E7
 *      416-504-9876
 */

#ifndef __SIM_ForceDrag_h__
#define __SIM_ForceDrag_h__

#include "SIM_API.h"
#include "SIM_Force.h"
#include "SIM_OptionsUser.h"

/// A simple drag force that opposes velocities in the normal direction.
class SIM_API SIM_ForceDrag : public SIM_Force,
                              public SIM_OptionsUser
{
public:
    GETSET_DATA_FUNCS_V3(SIM_NAME_VELOCITY, Velocity);
    GETSET_DATA_FUNCS_V3(SIM_NAME_ANGVELOCITY, AngularVelocityDegrees);
    GETSET_DATA_FUNCS_F(SIM_NAME_FORCESCALE, ForceScale);
    GETSET_DATA_FUNCS_F(SIM_NAME_TORQUESCALE, TorqueScale);

    /// Controls whether we cancel out mass (making it a delta-v rather
    /// than delta-momentum)
    GET_DATA_FUNC_B("ignoremass", IgnoreMass);
    /// Whether to sample by point, circle, or sphere.
    GETSET_DATA_FUNCS_I(SIM_NAME_SAMPLEMODE, SampleMode);

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

    /// Override the surface force calculation. The drag force opposes
    /// velocities.
    virtual 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;
    virtual 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;

    virtual 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;

    virtual SIM_ForceResolver *getForceResolverSubclass(const SIM_Object &object) const;
    virtual SIM_ForceSample     getOptimalForceSamplingSubclass() const;

private:
    /// Get the Automatic DOP description for creating a drag dop.
    static const SIM_DopDescription     *getForceDragDopDescription();

    DECLARE_STANDARD_GETCASTTOTYPE();
    DECLARE_DATAFACTORY(SIM_ForceDrag,
                        SIM_Force,
                        "Drag Force",
                        getForceDragDopDescription());
};

#endif

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