SIM/SIM_ForceMagnet.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_ForceMagnet_h__
#define __SIM_ForceMagnet_h__

#include "SIM_API.h"
#include "SIM_Force.h"
#include "SIM_OptionsUser.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_ForceMagnet : public SIM_Force,
                                public SIM_OptionsUser
{
public:
    /// Scale the calculated force value.
    GETSET_DATA_FUNCS_F(SIM_NAME_FORCESCALE, ForceScale);
    /// Whether to sample by point, circle, or sphere.
    GETSET_DATA_FUNCS_I(SIM_NAME_SAMPLEMODE, SampleMode);

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

    /// 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.
    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 SIM_ForceSample     getOptimalForceSamplingSubclass() const;

    /// 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.
    virtual SIM_Guide   *createGuideObjectSubclass() const;
    /// Build guide geometry by copying the points from the source geometry,
    /// and adding lines to represent the force and torque vectors.
    virtual void         buildGuideGeometrySubclass(const SIM_RootData &root,
                                                    const SIM_Options &options,
                                                    const GU_DetailHandle &gdh,
                                                    UT_DMatrix4 *xform,
                                                    const SIM_Time &t) const;

private:    
    static const SIM_DopDescription     *getForceMagnetDopDescription();
    
    // Builds the transform which goes from the geometry space to the
    // world space.
    void                 getGeometryToWorldTransform(UT_DMatrix4 &xform) const;
    // Builds the inverse transform which moves the world space into
    // the geometry space.
    void                 getWorldToGeometryTransform(UT_DMatrix4 &xform) const;
    
    DECLARE_STANDARD_GETCASTTOTYPE();
    DECLARE_DATAFACTORY(SIM_ForceMagnet,
                        SIM_Force,
                        "Magnet Force",
                        getForceMagnetDopDescription());
};

#endif

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