fmodifier.c

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/*
 * $Id: fmodifier.c 35953 2011-04-02 02:08:33Z campbellbarton $
 *
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2009 Blender Foundation, Joshua Leung
 * All rights reserved.
 *
 * Contributor(s): Joshua Leung (full recode)
 *
 * ***** END GPL LICENSE BLOCK *****
 */

#include <math.h>
#include <stdio.h>
#include <stddef.h>
#include <string.h>
#include <float.h>

#include "MEM_guardedalloc.h"

#include "DNA_anim_types.h"

#include "BLI_blenlib.h"
#include "BLI_math.h" /* windows needs for M_PI */
#include "BLI_utildefines.h"

#include "BKE_fcurve.h"
#include "BKE_idprop.h"


#define SMALL -1.0e-10
#define SELECT 1

/* ******************************** F-Modifiers ********************************* */

/* Info ------------------------------- */

/* F-Modifiers are modifiers which operate on F-Curves. However, they can also be defined
 * on NLA-Strips to affect all of the F-Curves referenced by the NLA-Strip. 
 */

/* Template --------------------------- */

/* Each modifier defines a set of functions, which will be called at the appropriate
 * times. In addition to this, each modifier should have a type-info struct, where
 * its functions are attached for use. 
 */
 
/* Template for type-info data:
 *      - make a copy of this when creating new modifiers, and just change the functions
 *        pointed to as necessary
 *      - although the naming of functions doesn't matter, it would help for code
 *        readability, to follow the same naming convention as is presented here
 *      - any functions that a constraint doesn't need to define, don't define
 *        for such cases, just use NULL 
 *      - these should be defined after all the functions have been defined, so that
 *        forward-definitions/prototypes don't need to be used!
 *      - keep this copy #if-def'd so that future constraints can get based off this
 */
#if 0
static FModifierTypeInfo FMI_MODNAME = {
        FMODIFIER_TYPE_MODNAME, /* type */
        sizeof(FMod_ModName), /* size */
        FMI_TYPE_SOME_ACTION, /* action type */
        FMI_REQUIRES_SOME_REQUIREMENT, /* requirements */
        "Modifier Name", /* name */
        "FMod_ModName", /* struct name */
        fcm_modname_free, /* free data */
        fcm_modname_relink, /* relink data */
        fcm_modname_copy, /* copy data */
        fcm_modname_new_data, /* new data */
        fcm_modname_verify, /* verify */
        fcm_modname_time, /* evaluate time */
        fcm_modname_evaluate /* evaluate */
};
#endif

/* Generator F-Curve Modifier --------------------------- */

/* Generators available:
 *      1) simple polynomial generator:
 *              - Exanded form - (y = C[0]*(x^(n)) + C[1]*(x^(n-1)) + ... + C[n])  
 *              - Factorised form - (y = (C[0][0]*x + C[0][1]) * (C[1][0]*x + C[1][1]) * ... * (C[n][0]*x + C[n][1]))
 */

static void fcm_generator_free (FModifier *fcm)
{
        FMod_Generator *data= (FMod_Generator *)fcm->data;
        
        /* free polynomial coefficients array */
        if (data->coefficients)
                MEM_freeN(data->coefficients);
}

static void fcm_generator_copy (FModifier *fcm, FModifier *src)
{
        FMod_Generator *gen= (FMod_Generator *)fcm->data;
        FMod_Generator *ogen= (FMod_Generator *)src->data;
        
        /* copy coefficients array? */
        if (ogen->coefficients)
                gen->coefficients= MEM_dupallocN(ogen->coefficients);
}

static void fcm_generator_new_data (void *mdata)
{
        FMod_Generator *data= (FMod_Generator *)mdata;
        float *cp;
        
        /* set default generator to be linear 0-1 (gradient = 1, y-offset = 0) */
        data->poly_order= 1;
        data->arraysize= 2;
        cp= data->coefficients= MEM_callocN(sizeof(float)*2, "FMod_Generator_Coefs");
        cp[0] = 0; // y-offset 
        cp[1] = 1; // gradient
}

static void fcm_generator_verify (FModifier *fcm)
{
        FMod_Generator *data= (FMod_Generator *)fcm->data;
        
        /* requirements depend on mode */
        switch (data->mode) {
                case FCM_GENERATOR_POLYNOMIAL: /* expanded polynomial expression */
                {
                        /* arraysize needs to be order+1, so resize if not */
                        if (data->arraysize != (data->poly_order+1)) {
                                float *nc;
                                
                                /* make new coefficients array, and copy over as much data as can fit */
                                nc= MEM_callocN(sizeof(float)*(data->poly_order+1), "FMod_Generator_Coefs");
                                
                                if (data->coefficients) {
                                        if ((int)data->arraysize > (data->poly_order+1))
                                                memcpy(nc, data->coefficients, sizeof(float)*(data->poly_order+1));
                                        else
                                                memcpy(nc, data->coefficients, sizeof(float)*data->arraysize);
                                                
                                        /* free the old data */
                                        MEM_freeN(data->coefficients);
                                }       
                                
                                /* set the new data */
                                data->coefficients= nc;
                                data->arraysize= data->poly_order+1;
                        }
                }
                        break;
                
                case FCM_GENERATOR_POLYNOMIAL_FACTORISED: /* expanded polynomial expression */
                {
                        /* arraysize needs to be 2*order, so resize if not */
                        if (data->arraysize != (data->poly_order * 2)) {
                                float *nc;
                                
                                /* make new coefficients array, and copy over as much data as can fit */
                                nc= MEM_callocN(sizeof(float)*(data->poly_order*2), "FMod_Generator_Coefs");
                                
                                if (data->coefficients) {
                                        if (data->arraysize > (unsigned int)(data->poly_order * 2))
                                                memcpy(nc, data->coefficients, sizeof(float)*(data->poly_order * 2));
                                        else
                                                memcpy(nc, data->coefficients, sizeof(float)*data->arraysize);
                                                
                                        /* free the old data */
                                        MEM_freeN(data->coefficients);
                                }       
                                
                                /* set the new data */
                                data->coefficients= nc;
                                data->arraysize= data->poly_order * 2;
                        }
                }
                        break;  
        }
}

static void fcm_generator_evaluate (FCurve *UNUSED(fcu), FModifier *fcm, float *cvalue, float evaltime)
{
        FMod_Generator *data= (FMod_Generator *)fcm->data;
        
        /* behaviour depends on mode 
         * NOTE: the data in its default state is fine too
         */
        switch (data->mode) {
                case FCM_GENERATOR_POLYNOMIAL: /* expanded polynomial expression */
                {
                        /* we overwrite cvalue with the sum of the polynomial */
                        float *powers = MEM_callocN(sizeof(float)*data->arraysize, "Poly Powers");
                        float value= 0.0f;
                        unsigned int i;
                        
                        /* for each x^n, precalculate value based on previous one first... this should be 
                         * faster that calling pow() for each entry
                         */
                        for (i=0; i < data->arraysize; i++) {
                                /* first entry is x^0 = 1, otherwise, calculate based on previous */
                                if (i)
                                        powers[i]= powers[i-1] * evaltime;
                                else
                                        powers[0]= 1;
                        }
                        
                        /* for each coefficient, add to value, which we'll write to *cvalue in one go */
                        for (i=0; i < data->arraysize; i++)
                                value += data->coefficients[i] * powers[i];
                        
                        /* only if something changed, write *cvalue in one go */
                        if (data->poly_order) {
                                if (data->flag & FCM_GENERATOR_ADDITIVE)
                                        *cvalue += value;
                                else
                                        *cvalue= value;
                        }
                                
                        /* cleanup */
                        if (powers) 
                                MEM_freeN(powers);
                }
                        break;
                        
                case FCM_GENERATOR_POLYNOMIAL_FACTORISED: /* factorised polynomial */
                {
                        float value= 1.0f, *cp=NULL;
                        unsigned int i;
                        
                        /* for each coefficient pair, solve for that bracket before accumulating in value by multiplying */
                        for (cp=data->coefficients, i=0; (cp) && (i < (unsigned int)data->poly_order); cp+=2, i++) 
                                value *= (cp[0]*evaltime + cp[1]);
                                
                        /* only if something changed, write *cvalue in one go */
                        if (data->poly_order) {
                                if (data->flag & FCM_GENERATOR_ADDITIVE)
                                        *cvalue += value;
                                else
                                        *cvalue= value;
                        }
                }
                        break;
        }
}

static FModifierTypeInfo FMI_GENERATOR = {
        FMODIFIER_TYPE_GENERATOR, /* type */
        sizeof(FMod_Generator), /* size */
        FMI_TYPE_GENERATE_CURVE, /* action type */
        FMI_REQUIRES_NOTHING, /* requirements */
        "Generator", /* name */
        "FMod_Generator", /* struct name */
        fcm_generator_free, /* free data */
        fcm_generator_copy, /* copy data */
        fcm_generator_new_data, /* new data */
        fcm_generator_verify, /* verify */
        NULL, /* evaluate time */
        fcm_generator_evaluate /* evaluate */
};

/* Built-In Function Generator F-Curve Modifier --------------------------- */

/* This uses the general equation for equations:
 *              y = amplitude * fn(phase_multiplier*x + phase_offset) + y_offset
 *
 * where amplitude, phase_multiplier/offset, y_offset are user-defined coefficients,
 * x is the evaluation 'time', and 'y' is the resultant value
 *
 * Functions available are
 *      sin, cos, tan, sinc (normalised sin), natural log, square root 
 */

static void fcm_fn_generator_new_data (void *mdata)
{
        FMod_FunctionGenerator *data= (FMod_FunctionGenerator *)mdata;
        
        /* set amplitude and phase multiplier to 1.0f so that something is generated */
        data->amplitude= 1.0f;
        data->phase_multiplier= 1.0f;
}

/* Unary 'normalised sine' function
 *      y = sin(PI + x) / (PI * x),
 * except for x = 0 when y = 1.
 */
static double sinc (double x)
{
        if (fabs(x) < 0.0001)
                return 1.0;
        else
                return sin(M_PI * x) / (M_PI * x);
}

static void fcm_fn_generator_evaluate (FCurve *UNUSED(fcu), FModifier *fcm, float *cvalue, float evaltime)
{
        FMod_FunctionGenerator *data= (FMod_FunctionGenerator *)fcm->data;
        double arg= data->phase_multiplier*evaltime + data->phase_offset;
        double (*fn)(double v) = NULL;
        
        /* get function pointer to the func to use:
         * WARNING: must perform special argument validation hereto guard against crashes  
         */
        switch (data->type)
        {
                /* simple ones */                       
                case FCM_GENERATOR_FN_SIN: /* sine wave */
                        fn= sin;
                        break;
                case FCM_GENERATOR_FN_COS: /* cosine wave */
                        fn= cos;
                        break;
                case FCM_GENERATOR_FN_SINC: /* normalised sine wave */
                        fn= sinc;
                        break;
                        
                /* validation required */
                case FCM_GENERATOR_FN_TAN: /* tangent wave */
                {
                        /* check that argument is not on one of the discontinuities (i.e. 90deg, 270 deg, etc) */
                        if IS_EQ(fmod((arg - M_PI_2), M_PI), 0.0) {
                                if ((data->flag & FCM_GENERATOR_ADDITIVE) == 0)
                                        *cvalue = 0.0f; /* no value possible here */
                        }
                        else
                                fn= tan;
                }
                        break;
                case FCM_GENERATOR_FN_LN: /* natural log */
                {
                        /* check that value is greater than 1? */
                        if (arg > 1.0) {
                                fn= log;
                        }
                        else {
                                if ((data->flag & FCM_GENERATOR_ADDITIVE) == 0)
                                        *cvalue = 0.0f; /* no value possible here */
                        }
                }
                        break;
                case FCM_GENERATOR_FN_SQRT: /* square root */
                {
                        /* no negative numbers */
                        if (arg > 0.0) {
                                fn= sqrt;
                        }
                        else {
                                if ((data->flag & FCM_GENERATOR_ADDITIVE) == 0)
                                        *cvalue = 0.0f; /* no value possible here */
                        }
                }
                        break;
                
                default:
                        printf("Invalid Function-Generator for F-Modifier - %d \n", data->type);
        }
        
        /* execute function callback to set value if appropriate */
        if (fn) {
                float value= (float)(data->amplitude*(float)fn(arg) + data->value_offset);
                
                if (data->flag & FCM_GENERATOR_ADDITIVE)
                        *cvalue += value;
                else
                        *cvalue= value;
        }
}

static FModifierTypeInfo FMI_FN_GENERATOR = {
        FMODIFIER_TYPE_FN_GENERATOR, /* type */
        sizeof(FMod_FunctionGenerator), /* size */
        FMI_TYPE_GENERATE_CURVE, /* action type */
        FMI_REQUIRES_NOTHING, /* requirements */
        "Built-In Function", /* name */
        "FMod_FunctionGenerator", /* struct name */
        NULL, /* free data */
        NULL, /* copy data */
        fcm_fn_generator_new_data, /* new data */
        NULL, /* verify */
        NULL, /* evaluate time */
        fcm_fn_generator_evaluate /* evaluate */
};

/* Envelope F-Curve Modifier --------------------------- */

static void fcm_envelope_free (FModifier *fcm)
{
        FMod_Envelope *env= (FMod_Envelope *)fcm->data;
        
        /* free envelope data array */
        if (env->data)
                MEM_freeN(env->data);
}

static void fcm_envelope_copy (FModifier *fcm, FModifier *src)
{
        FMod_Envelope *env= (FMod_Envelope *)fcm->data;
        FMod_Envelope *oenv= (FMod_Envelope *)src->data;
        
        /* copy envelope data array */
        if (oenv->data)
                env->data= MEM_dupallocN(oenv->data);
}

static void fcm_envelope_new_data (void *mdata)
{
        FMod_Envelope *env= (FMod_Envelope *)mdata;
        
        /* set default min/max ranges */
        env->min= -1.0f;
        env->max= 1.0f;
}

static void fcm_envelope_verify (FModifier *fcm)
{
        FMod_Envelope *env= (FMod_Envelope *)fcm->data;
        
        /* if the are points, perform bubble-sort on them, as user may have changed the order */
        if (env->data) {
                // XXX todo...
        }
}

static void fcm_envelope_evaluate (FCurve *UNUSED(fcu), FModifier *fcm, float *cvalue, float evaltime)
{
        FMod_Envelope *env= (FMod_Envelope *)fcm->data;
        FCM_EnvelopeData *fed, *prevfed, *lastfed;
        float min=0.0f, max=0.0f, fac=0.0f;
        int a;
        
        /* get pointers */
        if (env->data == NULL) return;
        prevfed= env->data;
        fed= prevfed + 1;
        lastfed= prevfed + (env->totvert-1);
        
        /* get min/max values for envelope at evaluation time (relative to mid-value) */
        if (prevfed->time >= evaltime) {
                /* before or on first sample, so just extend value */
                min= prevfed->min;
                max= prevfed->max;
        }
        else if (lastfed->time <= evaltime) {
                /* after or on last sample, so just extend value */
                min= lastfed->min;
                max= lastfed->max;
        }
        else {
                /* evaltime occurs somewhere between segments */
                // TODO: implement binary search for this to make it faster?
                for (a=0; prevfed && fed && (a < env->totvert-1); a++, prevfed=fed, fed++) {  
                        /* evaltime occurs within the interval defined by these two envelope points */
                        if ((prevfed->time <= evaltime) && (fed->time >= evaltime)) {
                                float afac, bfac, diff;
                                
                                diff= fed->time - prevfed->time;
                                afac= (evaltime - prevfed->time) / diff;
                                bfac= (fed->time - evaltime) / diff;
                                
                                min= bfac*prevfed->min + afac*fed->min;
                                max= bfac*prevfed->max + afac*fed->max;
                                
                                break;
                        }
                }
        }
        
        /* adjust *cvalue 
         *      - fac is the ratio of how the current y-value corresponds to the reference range
         *      - thus, the new value is found by mapping the old range to the new!
         */
        fac= (*cvalue - (env->midval + env->min)) / (env->max - env->min);
        *cvalue= min + fac*(max - min); 
}

static FModifierTypeInfo FMI_ENVELOPE = {
        FMODIFIER_TYPE_ENVELOPE, /* type */
        sizeof(FMod_Envelope), /* size */
        FMI_TYPE_REPLACE_VALUES, /* action type */
        0, /* requirements */
        "Envelope", /* name */
        "FMod_Envelope", /* struct name */
        fcm_envelope_free, /* free data */
        fcm_envelope_copy, /* copy data */
        fcm_envelope_new_data, /* new data */
        fcm_envelope_verify, /* verify */
        NULL, /* evaluate time */
        fcm_envelope_evaluate /* evaluate */
};

/* Cycles F-Curve Modifier  --------------------------- */

/* This modifier changes evaltime to something that exists within the curve's frame-range, 
 * then re-evaluates modifier stack up to this point using the new time. This re-entrant behaviour
 * is very likely to be more time-consuming than the original approach... (which was tighly integrated into 
 * the calculation code...).
 *
 * NOTE: this needs to be at the start of the stack to be of use, as it needs to know the extents of the keyframes/sample-data
 * Possible TODO - store length of cycle information that can be initialised from the extents of the keyframes/sample-data, and adjusted
 *                              as appropriate
 */

/* temp data used during evaluation */
typedef struct tFCMED_Cycles {
        float cycyofs;          /* y-offset to apply */
} tFCMED_Cycles;
 
static void fcm_cycles_new_data (void *mdata)
{
        FMod_Cycles *data= (FMod_Cycles *)mdata;
        
        /* turn on cycles by default */
        data->before_mode= data->after_mode= FCM_EXTRAPOLATE_CYCLIC;
}

static float fcm_cycles_time (FCurve *fcu, FModifier *fcm, float UNUSED(cvalue), float evaltime)
{
        FMod_Cycles *data= (FMod_Cycles *)fcm->data;
        float prevkey[2], lastkey[2], cycyofs=0.0f;
        short side=0, mode=0;
        int cycles=0, ofs=0;
        
        /* check if modifier is first in stack, otherwise disable ourself... */
        // FIXME...
        if (fcm->prev) {
                fcm->flag |= FMODIFIER_FLAG_DISABLED;
                return evaltime;
        }
        
        /* calculate new evaltime due to cyclic interpolation */
        if (fcu && fcu->bezt) {
                BezTriple *prevbezt= fcu->bezt;
                BezTriple *lastbezt= prevbezt + fcu->totvert-1;
                
                prevkey[0]= prevbezt->vec[1][0];
                prevkey[1]= prevbezt->vec[1][1];
                
                lastkey[0]= lastbezt->vec[1][0];
                lastkey[1]= lastbezt->vec[1][1];
        }
        else if (fcu && fcu->fpt) {
                FPoint *prevfpt= fcu->fpt;
                FPoint *lastfpt= prevfpt + fcu->totvert-1;
                
                prevkey[0]= prevfpt->vec[0];
                prevkey[1]= prevfpt->vec[1];
                
                lastkey[0]= lastfpt->vec[0];
                lastkey[1]= lastfpt->vec[1];
        }
        else
                return evaltime;
                
        /* check if modifier will do anything
         *      1) if in data range, definitely don't do anything
         *      2) if before first frame or after last frame, make sure some cycling is in use
         */
        if (evaltime < prevkey[0]) {
                if (data->before_mode)  {
                        side= -1;
                        mode= data->before_mode;
                        cycles= data->before_cycles;
                        ofs= prevkey[0];
                }
        }
        else if (evaltime > lastkey[0]) {
                if (data->after_mode) {
                        side= 1;
                        mode= data->after_mode;
                        cycles= data->after_cycles;
                        ofs= lastkey[0];
                }
        }
        if ELEM(0, side, mode)
                return evaltime;
                
        /* find relative place within a cycle */
        {
                float cycdx=0, cycdy=0;
                float cycle= 0, cyct=0;
                
                /* calculate period and amplitude (total height) of a cycle */
                cycdx= lastkey[0] - prevkey[0];
                cycdy= lastkey[1] - prevkey[1];
                
                /* check if cycle is infinitely small, to be point of being impossible to use */
                if (cycdx == 0)
                        return evaltime;
                        
                /* calculate the 'number' of the cycle */
                cycle= ((float)side * (evaltime - ofs) / cycdx);

                /* calculate the time inside the cycle */
                cyct= fmod(evaltime - ofs, cycdx);
                
                /* check that cyclic is still enabled for the specified time */
                if (cycles == 0) {
                        /* catch this case so that we don't exit when we have cycles=0
                         * as this indicates infinite cycles...
                         */
                }
                else if (cycle > cycles) {
                        /* we are too far away from range to evaluate
                         * TODO: but we should still hold last value... 
                         */
                        return evaltime;
                }
                
                /* check if 'cyclic extrapolation', and thus calculate y-offset for this cycle */
                if (mode == FCM_EXTRAPOLATE_CYCLIC_OFFSET) {
                        if(side < 0)
                                cycyofs = (float)floor((evaltime - ofs) / cycdx);
                        else
                                cycyofs = (float)ceil((evaltime - ofs) / cycdx);
                        cycyofs *= cycdy;
                }

                /* special case for cycle start/end */
                if(cyct == 0.0f) {
                        evaltime = (side == 1 ? lastkey[0] : prevkey[0]);

                        if((mode == FCM_EXTRAPOLATE_MIRROR) && ((int)cycle % 2))
                                evaltime = (side == 1 ? prevkey[0] : lastkey[0]);
                }
                /* calculate where in the cycle we are (overwrite evaltime to reflect this) */
                else if ((mode == FCM_EXTRAPOLATE_MIRROR) && ((int)(cycle+1) % 2)) {
                        /* when 'mirror' option is used and cycle number is odd, this cycle is played in reverse 
                         *      - for 'before' extrapolation, we need to flip in a different way, otherwise values past
                         *        then end of the curve get referenced (result of fmod will be negative, and with different phase)
                         */
                        if (side < 0)
                                evaltime= prevkey[0] - cyct;
                        else
                                evaltime= lastkey[0] - cyct;
                }
                else {
                        /* the cycle is played normally... */
                        evaltime= prevkey[0] + cyct;
                }
                if (evaltime < prevkey[0]) evaltime += cycdx;
        }
        
        /* store temp data if needed */
        if (mode == FCM_EXTRAPOLATE_CYCLIC_OFFSET) {
                tFCMED_Cycles *edata;
                
                /* for now, this is just a float, but we could get more stuff... */
                fcm->edata= edata= MEM_callocN(sizeof(tFCMED_Cycles), "tFCMED_Cycles");
                edata->cycyofs= cycyofs;
        }
        
        /* return the new frame to evaluate */
        return evaltime;
}
 
static void fcm_cycles_evaluate (FCurve *UNUSED(fcu), FModifier *fcm, float *cvalue, float UNUSED(evaltime))
{
        tFCMED_Cycles *edata= (tFCMED_Cycles *)fcm->edata;
        
        /* use temp data */
        if (edata) {
                /* add cyclic offset - no need to check for now, otherwise the data wouldn't exist! */
                *cvalue += edata->cycyofs;
                
                /* free temp data */
                MEM_freeN(edata);
                fcm->edata= NULL;
        }
}

static FModifierTypeInfo FMI_CYCLES = {
        FMODIFIER_TYPE_CYCLES, /* type */
        sizeof(FMod_Cycles), /* size */
        FMI_TYPE_EXTRAPOLATION, /* action type */
        FMI_REQUIRES_ORIGINAL_DATA, /* requirements */
        "Cycles", /* name */
        "FMod_Cycles", /* struct name */
        NULL, /* free data */
        NULL, /* copy data */
        fcm_cycles_new_data, /* new data */
        NULL /*fcm_cycles_verify*/, /* verify */
        fcm_cycles_time, /* evaluate time */
        fcm_cycles_evaluate /* evaluate */
};

/* Noise F-Curve Modifier  --------------------------- */

static void fcm_noise_new_data (void *mdata)
{
        FMod_Noise *data= (FMod_Noise *)mdata;
        
        /* defaults */
        data->size= 1.0f;
        data->strength= 1.0f;
        data->phase= 1.0f;
        data->depth = 0;
        data->modification = FCM_NOISE_MODIF_REPLACE;
}
 
static void fcm_noise_evaluate (FCurve *UNUSED(fcu), FModifier *fcm, float *cvalue, float evaltime)
{
        FMod_Noise *data= (FMod_Noise *)fcm->data;
        float noise;
        
        /* generate noise using good ol' Blender Noise
         *      - 0.1 is passed as the 'z' value, otherwise evaluation fails for size = phase = 1
         *        with evaltime being an integer (which happens when evaluating on frame by frame basis)
         */
        noise = BLI_turbulence(data->size, evaltime, data->phase, 0.1f, data->depth);
        
        /* combine the noise with existing motion data */
        switch (data->modification) {
                case FCM_NOISE_MODIF_ADD:
                        *cvalue= *cvalue + noise * data->strength;
                        break;
                case FCM_NOISE_MODIF_SUBTRACT:
                        *cvalue= *cvalue - noise * data->strength;
                        break;
                case FCM_NOISE_MODIF_MULTIPLY:
                        *cvalue= *cvalue * noise * data->strength;
                        break;
                case FCM_NOISE_MODIF_REPLACE:
                default:
                        *cvalue= *cvalue + (noise - 0.5f) * data->strength;
                        break;
        }
}

static FModifierTypeInfo FMI_NOISE = {
        FMODIFIER_TYPE_NOISE, /* type */
        sizeof(FMod_Noise), /* size */
        FMI_TYPE_REPLACE_VALUES, /* action type */
        0, /* requirements */
        "Noise", /* name */
        "FMod_Noise", /* struct name */
        NULL, /* free data */
        NULL, /* copy data */
        fcm_noise_new_data, /* new data */
        NULL /*fcm_noise_verify*/, /* verify */
        NULL, /* evaluate time */
        fcm_noise_evaluate /* evaluate */
};

/* Filter F-Curve Modifier --------------------------- */

#if 0 // XXX not yet implemented 
static FModifierTypeInfo FMI_FILTER = {
        FMODIFIER_TYPE_FILTER, /* type */
        sizeof(FMod_Filter), /* size */
        FMI_TYPE_REPLACE_VALUES, /* action type */
        0, /* requirements */
        "Filter", /* name */
        "FMod_Filter", /* struct name */
        NULL, /* free data */
        NULL, /* copy data */
        NULL, /* new data */
        NULL /*fcm_filter_verify*/, /* verify */
        NULL, /* evlauate time */
        fcm_filter_evaluate /* evaluate */
};
#endif // XXX not yet implemented


/* Python F-Curve Modifier --------------------------- */

static void fcm_python_free (FModifier *fcm)
{
        FMod_Python *data= (FMod_Python *)fcm->data;
        
        /* id-properties */
        IDP_FreeProperty(data->prop);
        MEM_freeN(data->prop);
}

static void fcm_python_new_data (void *mdata) 
{
        FMod_Python *data= (FMod_Python *)mdata;
        
        /* everything should be set correctly by calloc, except for the prop->type constant.*/
        data->prop = MEM_callocN(sizeof(IDProperty), "PyFModifierProps");
        data->prop->type = IDP_GROUP;
}

static void fcm_python_copy (FModifier *fcm, FModifier *src)
{
        FMod_Python *pymod = (FMod_Python *)fcm->data;
        FMod_Python *opymod = (FMod_Python *)src->data;
        
        pymod->prop = IDP_CopyProperty(opymod->prop);
}

static void fcm_python_evaluate (FCurve *UNUSED(fcu), FModifier *UNUSED(fcm), float *UNUSED(cvalue), float UNUSED(evaltime))
{
#ifdef WITH_PYTHON
        //FMod_Python *data= (FMod_Python *)fcm->data;
        
        /* FIXME... need to implement this modifier...
         *      It will need it execute a script using the custom properties 
         */
#endif /* WITH_PYTHON */
}

static FModifierTypeInfo FMI_PYTHON = {
        FMODIFIER_TYPE_PYTHON, /* type */
        sizeof(FMod_Python), /* size */
        FMI_TYPE_GENERATE_CURVE, /* action type */
        FMI_REQUIRES_RUNTIME_CHECK, /* requirements */
        "Python", /* name */
        "FMod_Python", /* struct name */
        fcm_python_free, /* free data */
        fcm_python_copy, /* copy data */
        fcm_python_new_data, /* new data */
        NULL /*fcm_python_verify*/, /* verify */
        NULL /*fcm_python_time*/, /* evaluate time */
        fcm_python_evaluate /* evaluate */
};


/* Limits F-Curve Modifier --------------------------- */

static float fcm_limits_time (FCurve *UNUSED(fcu), FModifier *fcm, float UNUSED(cvalue), float evaltime)
{
        FMod_Limits *data= (FMod_Limits *)fcm->data;
        
        /* check for the time limits */
        if ((data->flag & FCM_LIMIT_XMIN) && (evaltime < data->rect.xmin))
                return data->rect.xmin;
        if ((data->flag & FCM_LIMIT_XMAX) && (evaltime > data->rect.xmax))
                return data->rect.xmax;
                
        /* modifier doesn't change time */
        return evaltime;
}

static void fcm_limits_evaluate (FCurve *UNUSED(fcu), FModifier *fcm, float *cvalue, float UNUSED(evaltime))
{
        FMod_Limits *data= (FMod_Limits *)fcm->data;
        
        /* value limits now */
        if ((data->flag & FCM_LIMIT_YMIN) && (*cvalue < data->rect.ymin))
                *cvalue= data->rect.ymin;
        if ((data->flag & FCM_LIMIT_YMAX) && (*cvalue > data->rect.ymax))
                *cvalue= data->rect.ymax;
}

static FModifierTypeInfo FMI_LIMITS = {
        FMODIFIER_TYPE_LIMITS, /* type */
        sizeof(FMod_Limits), /* size */
        FMI_TYPE_GENERATE_CURVE, /* action type */  /* XXX... err... */   
        FMI_REQUIRES_RUNTIME_CHECK, /* requirements */
        "Limits", /* name */
        "FMod_Limits", /* struct name */
        NULL, /* free data */
        NULL, /* copy data */
        NULL, /* new data */
        NULL, /* verify */
        fcm_limits_time, /* evaluate time */
        fcm_limits_evaluate /* evaluate */
};

/* Stepped F-Curve Modifier --------------------------- */

static void fcm_stepped_new_data (void *mdata) 
{
        FMod_Stepped *data= (FMod_Stepped *)mdata;
        
        /* just need to set the step-size to 2-frames by default */
        // XXX: or would 5 be more normal?
        data->step_size = 2.0f;
}

static float fcm_stepped_time (FCurve *UNUSED(fcu), FModifier *fcm, float UNUSED(cvalue), float evaltime)
{
        FMod_Stepped *data= (FMod_Stepped *)fcm->data;
        int snapblock;
        
        /* check range clamping to see if we should alter the timing to achieve the desired results */
        if (data->flag & FCM_STEPPED_NO_BEFORE) {
                if (evaltime < data->start_frame)
                        return evaltime;
        }
        if (data->flag & FCM_STEPPED_NO_AFTER) {
                if (evaltime > data->end_frame)
                        return evaltime;
        }
        
        /* we snap to the start of the previous closest block of 'step_size' frames 
         * after the start offset has been discarded 
         *      - i.e. round down
         */
        snapblock = (int)((evaltime - data->offset) / data->step_size);
        
        /* reapply the offset, and multiple the snapblock by the size of the steps to get 
         * the new time to evaluate at 
         */
        return ((float)snapblock * data->step_size) + data->offset;
}

static FModifierTypeInfo FMI_STEPPED = {
        FMODIFIER_TYPE_STEPPED, /* type */
        sizeof(FMod_Limits), /* size */
        FMI_TYPE_GENERATE_CURVE, /* action type */  /* XXX... err... */   
        FMI_REQUIRES_RUNTIME_CHECK, /* requirements */
        "Stepped", /* name */
        "FMod_Stepped", /* struct name */
        NULL, /* free data */
        NULL, /* copy data */
        fcm_stepped_new_data, /* new data */
        NULL, /* verify */
        fcm_stepped_time, /* evaluate time */
        NULL /* evaluate */
};

/* F-Curve Modifier API --------------------------- */
/* All of the F-Curve Modifier api functions use FModifierTypeInfo structs to carry out
 * and operations that involve F-Curve modifier specific code.
 */

/* These globals only ever get directly accessed in this file */
static FModifierTypeInfo *fmodifiersTypeInfo[FMODIFIER_NUM_TYPES];
static short FMI_INIT= 1; /* when non-zero, the list needs to be updated */

/* This function only gets called when FMI_INIT is non-zero */
static void fmods_init_typeinfo (void) 
{
        fmodifiersTypeInfo[0]=  NULL;                                   /* 'Null' F-Curve Modifier */
        fmodifiersTypeInfo[1]=  &FMI_GENERATOR;                 /* Generator F-Curve Modifier */
        fmodifiersTypeInfo[2]=  &FMI_FN_GENERATOR;              /* Built-In Function Generator F-Curve Modifier */
        fmodifiersTypeInfo[3]=  &FMI_ENVELOPE;                  /* Envelope F-Curve Modifier */
        fmodifiersTypeInfo[4]=  &FMI_CYCLES;                    /* Cycles F-Curve Modifier */
        fmodifiersTypeInfo[5]=  &FMI_NOISE;                             /* Apply-Noise F-Curve Modifier */
        fmodifiersTypeInfo[6]=  NULL/*&FMI_FILTER*/;                    /* Filter F-Curve Modifier */  // XXX unimplemented
        fmodifiersTypeInfo[7]=  &FMI_PYTHON;                    /* Custom Python F-Curve Modifier */
        fmodifiersTypeInfo[8]=  &FMI_LIMITS;                    /* Limits F-Curve Modifier */
        fmodifiersTypeInfo[9]=  &FMI_STEPPED;                   /* Stepped F-Curve Modifier */
}

/* This function should be used for getting the appropriate type-info when only
 * a F-Curve modifier type is known
 */
FModifierTypeInfo *get_fmodifier_typeinfo (int type)
{
        /* initialise the type-info list? */
        if (FMI_INIT) {
                fmods_init_typeinfo();
                FMI_INIT = 0;
        }
        
        /* only return for valid types */
        if ( (type >= FMODIFIER_TYPE_NULL) && 
                 (type <= FMODIFIER_NUM_TYPES ) ) 
        {
                /* there shouldn't be any segfaults here... */
                return fmodifiersTypeInfo[type];
        }
        else {
                printf("No valid F-Curve Modifier type-info data available. Type = %i \n", type);
        }
        
        return NULL;
} 
 
/* This function should always be used to get the appropriate type-info, as it
 * has checks which prevent segfaults in some weird cases.
 */
FModifierTypeInfo *fmodifier_get_typeinfo (FModifier *fcm)
{
        /* only return typeinfo for valid modifiers */
        if (fcm)
                return get_fmodifier_typeinfo(fcm->type);
        else
                return NULL;
}

/* API --------------------------- */

/* Add a new F-Curve Modifier to the given F-Curve of a certain type */
FModifier *add_fmodifier (ListBase *modifiers, int type)
{
        FModifierTypeInfo *fmi= get_fmodifier_typeinfo(type);
        FModifier *fcm;
        
        /* sanity checks */
        if ELEM(NULL, modifiers, fmi)
                return NULL;
        
        /* special checks for whether modifier can be added */
        if ((modifiers->first) && (type == FMODIFIER_TYPE_CYCLES)) {
                /* cycles modifier must be first in stack, so for now, don't add if it can't be */
                // TODO: perhaps there is some better way, but for now, 
                printf("Error: Cannot add 'Cycles' modifier to F-Curve, as 'Cycles' modifier can only be first in stack. \n");
                return NULL;
        }
        
        /* add modifier itself */
        fcm= MEM_callocN(sizeof(FModifier), "F-Curve Modifier");
        fcm->type = type;
        fcm->flag = FMODIFIER_FLAG_EXPANDED;
        BLI_addtail(modifiers, fcm);
        
        /* tag modifier as "active" if no other modifiers exist in the stack yet */
        if (modifiers->first == modifiers->last)
                fcm->flag |= FMODIFIER_FLAG_ACTIVE;
        
        /* add modifier's data */
        fcm->data= MEM_callocN(fmi->size, fmi->structName);
        
        /* init custom settings if necessary */
        if (fmi->new_data)      
                fmi->new_data(fcm->data);
                
        /* return modifier for further editing */
        return fcm;
}

/* Make a copy of the specified F-Modifier */
FModifier *copy_fmodifier (FModifier *src)
{
        FModifierTypeInfo *fmi= fmodifier_get_typeinfo(src);
        FModifier *dst;
        
        /* sanity check */
        if (src == NULL)
                return NULL;
                
        /* copy the base data, clearing the links */
        dst = MEM_dupallocN(src);
        dst->next = dst->prev = NULL;
        
        /* make a new copy of the F-Modifier's data */
        dst->data = MEM_dupallocN(src->data);
        
        /* only do specific constraints if required */
        if (fmi && fmi->copy_data)
                fmi->copy_data(dst, src);
                
        /* return the new modifier */
        return dst;
}

/* Duplicate all of the F-Modifiers in the Modifier stacks */
void copy_fmodifiers (ListBase *dst, ListBase *src)
{
        FModifier *fcm, *srcfcm;
        
        if ELEM(NULL, dst, src)
                return;
        
        dst->first= dst->last= NULL;
        BLI_duplicatelist(dst, src);
        
        for (fcm=dst->first, srcfcm=src->first; fcm && srcfcm; srcfcm=srcfcm->next, fcm=fcm->next) {
                FModifierTypeInfo *fmi= fmodifier_get_typeinfo(fcm);
                
                /* make a new copy of the F-Modifier's data */
                fcm->data = MEM_dupallocN(fcm->data);
                
                /* only do specific constraints if required */
                if (fmi && fmi->copy_data)
                        fmi->copy_data(fcm, srcfcm);
        }
}

/* Remove and free the given F-Modifier from the given stack  */
int remove_fmodifier (ListBase *modifiers, FModifier *fcm)
{
        FModifierTypeInfo *fmi= fmodifier_get_typeinfo(fcm);
        
        /* sanity check */
        if (fcm == NULL)
                return 0;
        
        /* free modifier's special data (stored inside fcm->data) */
        if (fcm->data) {
                if (fmi && fmi->free_data)
                        fmi->free_data(fcm);
                        
                /* free modifier's data (fcm->data) */
                MEM_freeN(fcm->data);
        }
        
        /* remove modifier from stack */
        if (modifiers) {
                BLI_freelinkN(modifiers, fcm);
                return 1;
        } 
        else {
                // XXX this case can probably be removed some day, as it shouldn't happen...
                printf("remove_fmodifier() - no modifier stack given \n");
                MEM_freeN(fcm);
                return 0;
        }
}

/* Remove all of a given F-Curve's modifiers */
void free_fmodifiers (ListBase *modifiers)
{
        FModifier *fcm, *fmn;
        
        /* sanity check */
        if (modifiers == NULL)
                return;
        
        /* free each modifier in order - modifier is unlinked from list and freed */
        for (fcm= modifiers->first; fcm; fcm= fmn) {
                fmn= fcm->next;
                remove_fmodifier(modifiers, fcm);
        }
}

/* Find the active F-Modifier */
FModifier *find_active_fmodifier (ListBase *modifiers)
{
        FModifier *fcm;
        
        /* sanity checks */
        if ELEM(NULL, modifiers, modifiers->first)
                return NULL;
        
        /* loop over modifiers until 'active' one is found */
        for (fcm= modifiers->first; fcm; fcm= fcm->next) {
                if (fcm->flag & FMODIFIER_FLAG_ACTIVE)
                        return fcm;
        }
        
        /* no modifier is active */
        return NULL;
}

/* Set the active F-Modifier */
void set_active_fmodifier (ListBase *modifiers, FModifier *fcm)
{
        FModifier *fm;
        
        /* sanity checks */
        if ELEM(NULL, modifiers, modifiers->first)
                return;
        
        /* deactivate all, and set current one active */
        for (fm= modifiers->first; fm; fm= fm->next)
                fm->flag &= ~FMODIFIER_FLAG_ACTIVE;
        
        /* make given modifier active */
        if (fcm)
                fcm->flag |= FMODIFIER_FLAG_ACTIVE;
}

/* Do we have any modifiers which match certain criteria 
 *      - mtype - type of modifier (if 0, doesn't matter)
 *      - acttype - type of action to perform (if -1, doesn't matter)
 */
short list_has_suitable_fmodifier (ListBase *modifiers, int mtype, short acttype)
{
        FModifier *fcm;
        
        /* if there are no specific filtering criteria, just skip */
        if ((mtype == 0) && (acttype == 0))
                return (modifiers && modifiers->first);
                
        /* sanity checks */
        if ELEM(NULL, modifiers, modifiers->first)
                return 0;
                
        /* find the first mdifier fitting these criteria */
        for (fcm= modifiers->first; fcm; fcm= fcm->next) {
                FModifierTypeInfo *fmi= fmodifier_get_typeinfo(fcm);
                short mOk=1, aOk=1; /* by default 1, so that when only one test, won't fail */
                
                /* check if applicable ones are fullfilled */
                if (mtype)
                        mOk= (fcm->type == mtype);
                if (acttype > -1)
                        aOk= (fmi->acttype == acttype);
                        
                /* if both are ok, we've found a hit */
                if (mOk && aOk)
                        return 1;
        }
        
        /* no matches */
        return 0;
}  

/* Evaluation API --------------------------- */

/* evaluate time modifications imposed by some F-Curve Modifiers
 *      - this step acts as an optimisation to prevent the F-Curve stack being evaluated 
 *        several times by modifiers requesting the time be modified, as the final result
 *        would have required using the modified time
 *      - modifiers only ever receive the unmodified time, as subsequent modifiers should be
 *        working on the 'global' result of the modified curve, not some localised segment,
 *        so nevaltime gets set to whatever the last time-modifying modifier likes...
 *      - we start from the end of the stack, as only the last one matters for now
 */
float evaluate_time_fmodifiers (ListBase *modifiers, FCurve *fcu, float cvalue, float evaltime)
{
        FModifier *fcm;
        
        /* sanity checks */
        if ELEM(NULL, modifiers, modifiers->last)
                return evaltime;
                
        /* Starting from the end of the stack, calculate the time effects of various stacked modifiers 
         * on the time the F-Curve should be evaluated at. 
         *
         * This is done in reverse order to standard evaluation, as when this is done in standard
         * order, each modifier would cause jumps to other points in the curve, forcing all
         * previous ones to be evaluated again for them to be correct. However, if we did in the 
         * reverse order as we have here, we can consider them a macro to micro type of waterfall
         * effect, which should get us the desired effects when using layered time manipulations
         * (such as multiple 'stepped' modifiers in sequence, causing different stepping rates)
         */
        for (fcm= modifiers->last; fcm; fcm= fcm->prev) {
                FModifierTypeInfo *fmi= fmodifier_get_typeinfo(fcm);
                
                /* only evaluate if there's a callback for this */
                // TODO: implement the 'influence' control feature...
                if (fmi && fmi->evaluate_modifier_time) {
                        if ((fcm->flag & (FMODIFIER_FLAG_DISABLED|FMODIFIER_FLAG_MUTED)) == 0)
                                evaltime= fmi->evaluate_modifier_time(fcu, fcm, cvalue, evaltime);
                }
        }
        
        /* return the modified evaltime */
        return evaltime;
}

/* Evalautes the given set of F-Curve Modifiers using the given data
 * Should only be called after evaluate_time_fmodifiers() has been called...
 */
void evaluate_value_fmodifiers (ListBase *modifiers, FCurve *fcu, float *cvalue, float evaltime)
{
        FModifier *fcm;
        
        /* sanity checks */
        if ELEM(NULL, modifiers, modifiers->first)
                return;
        
        /* evaluate modifiers */
        for (fcm= modifiers->first; fcm; fcm= fcm->next) {
                FModifierTypeInfo *fmi= fmodifier_get_typeinfo(fcm);
                
                /* only evaluate if there's a callback for this */
                // TODO: implement the 'influence' control feature...
                if (fmi && fmi->evaluate_modifier) {
                        if ((fcm->flag & (FMODIFIER_FLAG_DISABLED|FMODIFIER_FLAG_MUTED)) == 0)
                                fmi->evaluate_modifier(fcu, fcm, cvalue, evaltime);
                }
        }
} 

/* ---------- */

/* Bake modifiers for given F-Curve to curve sample data, in the frame range defined
 * by start and end (inclusive).
 */
void fcurve_bake_modifiers (FCurve *fcu, int start, int end)
{
        ChannelDriver *driver;
        
        /* sanity checks */
        // TODO: make these tests report errors using reports not printf's
        if ELEM(NULL, fcu, fcu->modifiers.first) {
                printf("Error: No F-Curve with F-Curve Modifiers to Bake\n");
                return;
        }
        
        /* temporarily, disable driver while we sample, so that they don't influence the outcome */
        driver= fcu->driver;
        fcu->driver= NULL;
        
        /* bake the modifiers, by sampling the curve at each frame */
        fcurve_store_samples(fcu, NULL, start, end, fcurve_samplingcb_evalcurve);
        
        /* free the modifiers now */
        free_fmodifiers(&fcu->modifiers);
        
        /* restore driver */
        fcu->driver= driver;
}