SIM_ForceOrbit.C

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/*
 * Copyright (c) 2024
 *      Side Effects Software Inc.  All rights reserved.
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 * Redistribution and use of Houdini Development Kit samples in source and
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#include "SIM_ForceOrbit.h"
#include <UT/UT_DSOVersion.h>
#include <GU/GU_PrimPoly.h>
#include <PRM/PRM_Include.h>
#include <SIM/SIM_PRMShared.h>
#include <SIM/SIM_DopDescription.h>
#include <SIM/SIM_GuideShared.h>

using namespace HDK_Sample;

void
initializeSIM(void *)
{
    IMPLEMENT_DATAFACTORY(SIM_ForceOrbit);
}

SIM_ForceOrbit::SIM_ForceOrbit(const SIM_DataFactory *factory)
    : BaseClass(factory),
      SIM_OptionsUser(this)
{
}

SIM_ForceOrbit::~SIM_ForceOrbit()
{
}

static PRM_Name theGuideShowName(SIM_NAME_SHOWGUIDE, "Show Guide");
static PRM_Name theGuideSizeName(SIM_NAME_SCALE, "Scale");
static PRM_Name theGuideColorName(SIM_NAME_COLOR, "Color");

const SIM_DopDescription *
SIM_ForceOrbit::getForceOrbitDopDescription()
{
    static PRM_Name      thePointPositionName(SIM_NAME_POINTPOSITION,
                                        "Point Position");
    static PRM_Name      thePointMassName(SIM_NAME_POINTMASS,
                                        "Point Mass");

    // define a template for parameters to control the force's behavior
    static PRM_Template          theTemplates[] = {
        PRM_Template(PRM_XYZ_J,         3, &thePointPositionName),
        PRM_Template(PRM_FLT_J,         1, &thePointMassName, PRMoneDefaults),
        PRM_Template()
    };

    // define a template for parameters to control the guide geometry
    static PRM_Template          theGuideTemplates[] = {
        PRM_Template(PRM_TOGGLE,        1, &theGuideShowName, PRMoneDefaults),
        PRM_Template(PRM_FLT_J,         1, &theGuideSizeName, PRMoneDefaults),
        PRM_Template(PRM_RGB_J,         3, &theGuideColorName, PRMoneDefaults),
        PRM_Template()
    };

    static SIM_DopDescription    theDopDescription(true,
                                                "hdk_orbit",
                                                "Orbit Force",
                                                SIM_FORCES_DATANAME "/Orbit",
                                                classname(),
                                                theTemplates);
    theDopDescription.setGuideTemplates(theGuideTemplates);
    theDopDescription.setDefaultUniqueDataName(1);

    return &theDopDescription;
}

SIM_Guide *
SIM_ForceOrbit::createGuideObjectSubclass() const
{   
    return new SIM_GuideShared(this, true);
}   

void
SIM_ForceOrbit::buildGuideGeometrySubclass(const SIM_RootData &root,
                                           const SIM_Options &options,
                                           const GU_DetailHandle &gdh,
                                           UT_DMatrix4 *xform,
                                           const SIM_Time &t) const
{
    // return immediately if no guide geometry should be displayed
    if( !options.hasOption(theGuideShowName.getToken()) ||
        !options.getOptionB(theGuideShowName.getToken()) )
        return;

    if( !gdh.isNull() )
    {
        GU_DetailHandleAutoWriteLock     gdl(gdh);
        GU_Detail                       *gdp = gdl.getGdp();

        // add a color attribute
#if defined(HOUDINI_11)
        GB_AttributeRef attCd = gdp->addDiffuseAttribute(GEO_PRIMITIVE_DICT);
#else
        GA_RWHandleV3 attCd(gdp->addDiffuseAttribute(GA_ATTRIB_PRIMITIVE));
#endif
        UT_Vector3 color(1, 1, 1);
        if( options.hasOption(theGuideColorName.getToken()) )
            color = options.getOptionV3(theGuideColorName.getToken());

        // create three mutualy perpendicular lines to indicate the position
        GA_Offset ptoff = gdp->appendPointBlock(6);
        for(int axis = 0; axis < 3; ++axis)
        {
            const GA_Offset pt0 = ptoff++;
            const GA_Offset pt1 = ptoff++;

            // re-position each point
            UT_Vector3 pos(0, 0, 0);
            pos(axis) = -0.5;
            gdp->setPos3(pt0, pos);
            pos(axis) = 0.5;
            gdp->setPos3(pt1, pos);

            // create a colored line connecting the two points
#if defined(HOUDINI_11)
            GU_PrimPoly *poly = (GU_PrimPoly *)gdp->appendPrimitive(GEOPRIMPOLY);
#else
            GU_PrimPoly *poly = (GU_PrimPoly *)gdp->appendPrimitive(GEO_PRIMPOLY);
#endif
            if(attCd.isValid())
                attCd.set(poly->getMapOffset(), color);
            poly->appendVertex(pt0);
            poly->appendVertex(pt1);
        }
    }
    if( xform )
    {
        // scale the guide geometry
        xform->identity();
        if( options.hasOption(theGuideSizeName.getToken()) )
        {
            fpreal scale = options.getOptionF(theGuideSizeName.getToken());
            xform->scale(scale, scale, scale);
        }

        // position the guide geometry
        UT_Vector3 pos = getPointPosition();
        xform->translate(pos.x(), pos.y(), pos.z());
    }
}

void
SIM_ForceOrbit::getForceSubclass(const SIM_Object &,
                                 const UT_Vector3 &position,
                                 const UT_Vector3 &,
                                 const UT_Vector3 &,
                                 const fpreal mass,
                                 UT_Vector3 &force,
                                 UT_Vector3 &torque) const
{
    UT_Vector3   pointposition = getPointPosition();
    fpreal       distancesquared;

    // Note that we don't use any gravitational constant G in this
    // calculation. This is because if we used a real value of G we'd
    // have to make our point mass about 10^10 before it would exert a
    // noticeable force.
    distancesquared = distance2(position, pointposition);
    if( !SYSequalZero(distancesquared) )
    {
        force = pointposition - position;
        force *= (mass * getPointMass()) / distancesquared;
    }
    else
        force = 0.0;
    torque = 0.0;
    applyNoise(position, force);
}

void
SIM_ForceOrbit::getForceOnCircleSubclass(const SIM_Object &object,
                                         const UT_Vector3 &position,
                                         const UT_Vector3 &,
                                         const fpreal,
                                         const UT_Vector3 &velocity,
                                         const UT_Vector3 &angvel,
                                         const fpreal mass,
                                         UT_Vector3 &force,
                                         UT_Vector3 &torque) const
{
    getForceSubclass(object, position, velocity, angvel, mass, force, torque);
}

void
SIM_ForceOrbit::getForceOnSphereSubclass(const SIM_Object &object,
                                         const UT_Vector3 &position,
                                         const fpreal,
                                         const UT_Vector3 &velocity,
                                         const UT_Vector3 &angvel,
                                         const fpreal mass,
                                         UT_Vector3 &force,
                                         UT_Vector3 &torque) const
{
    getForceSubclass(object, position, velocity, angvel, mass, force, torque);
}