CHOP_Spring.C

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/*
 * Copyright (c) 2021
 *      Side Effects Software Inc.  All rights reserved.
 *
 * Redistribution and use of Houdini Development Kit samples in source and
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 * following conditions are met:
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#include <UT/UT_DSOVersion.h>
#include <OP/OP_OperatorTable.h>

#include <CH/CH_LocalVariable.h>
#include <PRM/PRM_Include.h>
#include <CHOP/PRM_ChopShared.h>

#include <UT/UT_Interrupt.h>
#include <UT/UT_IStream.h>
#include <UT/UT_OStream.h>

#include "CHOP_Spring.h"

using namespace HDK_Sample;

CHOP_SWITCHER(7, "Spring");

static PRM_Name names[] = {
    PRM_Name("springk",         "Spring Constant"),
    PRM_Name("mass",            "Mass"),
    PRM_Name("dampingk",        "Damping Constant"),
    PRM_Name("method",          "Input Effect"),
    PRM_Name("condfromchan",    "Initial Conditions From Channel"),
    PRM_Name("initpos",         "Initial Position"),
    PRM_Name("initspeed",       "Initial Speed"),
    PRM_Name(0),
};

static PRM_Name springMethodItems[] = {
    PRM_Name("disp",    "Position"),
    PRM_Name("force",   "Force"),
    PRM_Name(0),
};

static PRM_ChoiceList springMethodMenu((PRM_ChoiceListType)
                                       (PRM_CHOICELIST_EXCLUSIVE | 
                                        PRM_CHOICELIST_REPLACE),
                                       springMethodItems);

static PRM_Range springConstantRange(PRM_RANGE_RESTRICTED, 0.0, 
                                     PRM_RANGE_UI, 1000.0);

static PRM_Range massRange(PRM_RANGE_UI, 0.1, 
                           PRM_RANGE_UI, 10.0);

static PRM_Range dampingConstantRange(PRM_RANGE_RESTRICTED, 0.0, 
                                      PRM_RANGE_UI, 10.0);

static PRM_Range initDispRange(PRM_RANGE_UI, -10.0, 
                               PRM_RANGE_UI,  10.0);

static PRM_Range initVelRange(PRM_RANGE_UI, -100.0, 
                              PRM_RANGE_UI,  100.0);

static PRM_Default     springConstantDefault(100.0);
static PRM_Default     massDefault(1.0);
static PRM_Default     dampingConstantDefault(1.0);
static PRM_Default     initDispDefault(0.0);
static PRM_Default     initVelDefault(0.0);

PRM_Template
CHOP_Spring::myTemplateList[] =
{
    PRM_Template(PRM_SWITCHER,  2, &PRMswitcherName, switcher),

    // First Page
    PRM_Template(PRM_FLT,       1, &names[0], &springConstantDefault, 0,
                                   &springConstantRange),
    PRM_Template(PRM_FLT,       1, &names[1], &massDefault, 0,
                                   &massRange),
    PRM_Template(PRM_FLT,       1, &names[2], &dampingConstantDefault, 0,
                                   &dampingConstantRange),
    PRM_Template(PRM_ORD,       1, &names[3], PRMzeroDefaults,
                                   &springMethodMenu),
    PRM_Template(PRM_TOGGLE,    1, &names[4], PRMoneDefaults),
    PRM_Template(PRM_FLT,       1, &names[5], &initDispDefault, 0,
                                   &initDispRange),
    PRM_Template(PRM_FLT,       1, &names[6], &initVelDefault, 0,
                                   &initVelRange),
    PRM_Template(),
};

OP_TemplatePair CHOP_Spring::myTemplatePair(
    CHOP_Spring::myTemplateList, &CHOP_Node::myTemplatePair);

bool
CHOP_Spring::updateParmsFlags()
{
    bool changes = CHOP_Node::updateParmsFlags();
    bool grab = GRAB_INITIAL();

    changes |= enableParm("initpos",    !grab);
    changes |= enableParm("initspeed",  !grab);

    return changes;
}


// 2 local variables, 'C' (the currently cooking track), 'NC' total # tracks.
enum
{
    VAR_C               = 200,
    VAR_NC              = 201
};
CH_LocalVariable
CHOP_Spring::myVariableList[] = {
    { "C",              VAR_C, 0 },
    { "NC",             VAR_NC, 0 },
    { 0, 0, 0 }
};
OP_VariablePair CHOP_Spring::myVariablePair(
    CHOP_Spring::myVariableList, &CHOP_Node::myVariablePair);

bool
CHOP_Spring::evalVariableValue(fpreal &val, int index, int thread)
{
    switch(index)
    {
    case VAR_C:
        // C marks the parameter as channel dependent - it must be re-eval'd
        // for each track processed.
        myChannelDependent=1;
        val = (fpreal)my_C;
        return true;
        
    case VAR_NC:
        val = (fpreal)my_NC;
        return true;
        
    }
    
    return CHOP_Node::evalVariableValue(val, index, thread);
}

//----------------------------------------------------------------------------

OP_Node *
CHOP_Spring::myConstructor(OP_Network   *net,
                        const char      *name,
                        OP_Operator     *op)
{
    return new CHOP_Spring(net, name, op);
}


CHOP_Spring::CHOP_Spring( OP_Network    *net,
                    const char  *name,
                    OP_Operator *op)
           : CHOP_Realtime(net, name, op)
{
    myParmBase = getParmList()->getParmIndex( names[0].getToken() );
    mySteady = 0;
}

CHOP_Spring::~CHOP_Spring()
{
}

// Regular cook method
OP_ERROR
CHOP_Spring::cookMyChop(OP_Context &context)
{
    const CL_Clip       *clip  = 0;
    const CL_Track      *track = 0;
    CL_Track            *new_track = 0;
    int                  force_method;
    int                  i, j,length, num_tracks, animated_parms;
    fpreal               spring_constant;
    fpreal               d1,d2,f,inc,d;
    fpreal               mass;
    fpreal               damping_constant;
    fpreal               initial_displacement;
    fpreal               initial_velocity;
    fpreal               acc, vel;
    UT_Interrupt        *boss;
    int                  stop;
    int                  count = 0xFFFF;
    bool                 grab_init = GRAB_INITIAL();

    // Copy the structure of the input, but not the data itself.
    clip = copyInput(context, 0, 0, 1); 
    if (!clip)
        return error();

    force_method         = METHOD();

    // Initialize local variables
    my_NC = clip->getNumTracks();
    my_C= 0;
    
    // evaluate all parameters and check if any are animated per channel with C
    myChannelDependent=0;
    spring_constant      = SPRING_CONSTANT(context.getTime());
    mass                 = MASS(context.getTime());
    damping_constant     = DAMPING_CONSTANT(context.getTime());
    animated_parms = myChannelDependent;
    
    inc = 1.0 / myClip->getSampleRate();

    // If 'grab initial' is true, we determine the initial values from the
    // input channel data instead of using the parameter settings (using
    // the position and slope of the track at the first sample).
    if(!grab_init)
    {
        initial_displacement = INITIAL_DISPLACEMENT(context.getTime());
        initial_velocity     = INITIAL_VELOCITY(context.getTime());
    }

    // An evaluation error occurred; exit.
    if (error() >= UT_ERROR_ABORT)
        return error();

    // Mass must be > 0. 
    if (mass < 0.001)
    {
        mass = 0.001;
        SET_MASS(context.getTime(), mass);
    }

    // Begin the interruptable operation
    boss = UTgetInterrupt();
    stop = 0;
    if(boss->opStart("Calculating Spring"))
    {
        if (clip)
        {
            num_tracks = clip->getNumTracks();
            length     = clip->getTrackLength();

            // Loop over all the tracks
            for (i=0; i<num_tracks; i++)
            {
                // update the local variable 'C' with the track number
                my_C = i;
                
                track     = clip->getTrack(i);
                new_track = myClip->getTrack(i);

                // If the track is not scoped, copy it and continue to the next
                if (!isScoped(track->getName()))
                {
                    *new_track = *track;
                    continue;
                }
                
                if(grab_init || animated_parms)
                {
                    // re-evaluate parameters if one of them was determined to
                    // depend on the local var 'C' (track number)
                    if(animated_parms)
                    {
                        spring_constant  = SPRING_CONSTANT(context.getTime());
                        mass             = MASS(context.getTime());
                        if (mass < 0.001)
                            mass = 0.001;
                        damping_constant = DAMPING_CONSTANT(context.getTime());
                    }

                    // If determining the position and speed from the track,
                    // evaluate the first 2 samples and difference them.
                    if(grab_init)
                    {
                        initial_displacement = clip->evaluateSingle(track,0);
                        initial_velocity=(clip->evaluateSingle(track,1) -
                                          initial_displacement);
                    }
                }

                // Run the spring algorithm on the track's data.
                d1 = initial_displacement; 
                d2 = d1 - initial_velocity * inc;
                
                for(j=0; j<length; j++)
                {
                    // Periodically check for interrupts.
                    if(count--==0 && boss->opInterrupt())
                    {
                        stop = 1;
                        break;
                    }

                    // run the spring equation
                    f = track->getData()[j];
                    if(!force_method)
                        f *= spring_constant;

                    vel = (d1-d2) / inc;
                    
                    acc = (f - vel*damping_constant - d1*spring_constant)/mass;
                    vel += acc * inc;
                    d = d1 + vel * inc; 
                    
                    new_track->getData()[j] = d;

                    // update the previous displacements
                    d2 = d1;
                    d1 = d;
                }

                if(stop || boss->opInterrupt())
                {
                    stop = 1;
                    break;
                }
            }
        }
    }
    // opEnd must always be called, even if opStart() returned 0.
    boss->opEnd();
    
    return error();
}

// -------------------------------------------------------------------------
// Time Slice cooking

// ---------------------------------------------------------------------------
// Realtime data block for stashing intermediate values between realtime cooks
// Only used in Time Slice mode.

namespace HDK_Sample {
class ut_SpringData : public ut_RealtimeData
{
public:
                ut_SpringData(const char *name,fpreal d,fpreal v);
                ~ut_SpringData() override {}

    fpreal      myDn1;
    fpreal      myDn2;

    bool        loadStates(UT_IStream &is, int version) override;
    bool        saveStates(UT_OStream &os) override;
};
}

ut_SpringData::ut_SpringData(const char *name, fpreal d1, fpreal d2)
    : ut_RealtimeData(name),
      myDn1(d1),
      myDn2(d2)
{
}
 
bool
ut_SpringData::loadStates(UT_IStream &is, int version)
{
    if (!ut_RealtimeData::loadStates(is, version))
        return false;

    if (!is.read<fpreal64>(&myDn1))
        return false;
    if (!is.read<fpreal64>(&myDn2))
        return false;
    return true;
}
 
bool
ut_SpringData::saveStates(UT_OStream &os)
{
    ut_RealtimeData::saveStates(os);

    os.write<fpreal64>(&myDn1);
    os.write<fpreal64>(&myDn2);
    return true;
}
    
int
CHOP_Spring::isSteady() const
{
    // 'Steady' indicates that the CHOP has reached a steady state and can
    // stop cooking every frame. An input must change in order to begin
    // springing again.
    return mySteady;
}

OP_ERROR
CHOP_Spring::cookMySlice(OP_Context &context, int start, int end)
{
    const CL_Clip       *clip  = inputClip(0,context);
    const CL_Track      *track = 0;
    CL_Track            *new_track = 0;
    int                  force_method;
    int                  i, j;
    fpreal               spring_constant;
    fpreal               mass;
    fpreal               d1,d2,f,t,inc,d, acc,vel,oldp;
    fpreal               damping_constant;
    ut_SpringData       *block;
    fpreal               delta;
    int                  animated_parms;
    
    force_method         = METHOD();

    my_NC = clip->getNumTracks();
    my_C= 0;

    // Again, evaluate the parameters and see if they depend on C
    myChannelDependent=0;
    spring_constant      = SPRING_CONSTANT(context.getTime());
    mass                 = MASS(context.getTime());
    damping_constant     = DAMPING_CONSTANT(context.getTime());
    animated_parms = myChannelDependent;
    inc                  = 1.0 / myClip->getSampleRate();
    
    if (mass < 0.001)
        mass = 0.001;

    mySteady = 1;

    for(i=0; i<myClip->getNumTracks(); i++)
    {
        my_C = i;
        
        track     = clip->getTrack(i);
        new_track = myClip->getTrack(i);

        // If this track isn't scoped, just copy the data.
        if(!isScoped(new_track->getName()))
        {
            clip->evaluateTime(track,
                               myClip->getTime(start+myClip->getStart()),
                               myClip->getTime(end+myClip->getStart()),
                               new_track->getData(), myClip->getTrackLength());
            continue;
        }

        // Re-evaluate the spring parameters if one of them depends on C
        if(animated_parms)
        {
            spring_constant  = SPRING_CONSTANT(context.getTime());
            mass             = MASS(context.getTime());
            if (mass < 0.001)
                mass = 0.001;
            damping_constant = DAMPING_CONSTANT(context.getTime());
        }

        // Create or grab the realtime data block associated with this track.
        // This will keep our results from the previous cook, in this case,
        // the previous 2 displacements.
        block = (ut_SpringData *) getDataBlock(i);
        
        d1 = block->myDn1;
        d2 = block->myDn2;

        // Loop over each sample in the track.
        for(j=0; j<myClip->getTrackLength(); j++)
        {
            t = myClip->getTime(myClip->getStart() + j);
            oldp = f = clip->evaluateSingleTime(track, t);

            // Run the spring equation
            if(!force_method)
                f *= spring_constant;
            else
                oldp /=spring_constant;

            vel = (d1-d2) / inc;

            acc = (f - vel*damping_constant - d1*spring_constant)/mass;
            vel += acc * inc;
            d = d1 + vel * inc; 
                
            delta = SYSabs(oldp - d);
            if (delta > 0.001)
                mySteady = 0;

            new_track->getData()[j] = d;

            d2 = d1;
            d1 = d;
        }

        // update the displacements in the realtime data block for the next cook
        // to use.
        block->myDn1 = d1;
        block->myDn2 = d2;
   }

    return error();
}

ut_RealtimeData *
CHOP_Spring::newRealtimeDataBlock(const char *name,
                                  const CL_Track *track,
                                  fpreal t)
{
    fpreal               d, d1, v, rate;

    // This creates a new realtime data block to stash intermediate values into.
    // In this case, the previous two displacements.
    if(GRAB_INITIAL() && track)
    {
        const CL_Clip   *clip = track ? track->getClip() : 0;
        
        d = clip->evaluateSingle(track,clip->getIndex(t));
        v = clip->evaluateSingle(track,clip->getIndex(t)+1) - d;
    }
    else
    {
        d = INITIAL_DISPLACEMENT(t);
        v = INITIAL_VELOCITY(t);
    }

    // The n-1 displacement is extrapolated from the slope at n and the
    // displacement (position) at n.
    rate = myClip->getSampleRate();
    if(rate != 0.0)
        d1 = d - v/rate;
    else
        d1 = d;

    return new ut_SpringData(name, d,d1);
}


// install the chop.
void newChopOperator(OP_OperatorTable *table)
{
    table->addOperator(new OP_Operator("hdk_spring", // node name
                                       "HDK Spring", // pretty name
                                       CHOP_Spring::myConstructor,
                                       &CHOP_Spring::myTemplatePair,
                                       1,       // min inputs
                                       1,       // max inputs 
                                       &CHOP_Spring::myVariablePair));
}