/*
 * ***** 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) 2008, Blender Foundation
 * This is a new part of Blender
 *
 * Contributor(s): Joshua Leung
 *                 Bastien Montagne
 *
 * ***** END GPL LICENSE BLOCK *****
 *
 * Operator for converting Grease Pencil data to geometry
 */

/** \file blender/editors/gpencil/gpencil_convert.c
 *  \ingroup edgpencil
 */


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

#include "MEM_guardedalloc.h"

#include "BLI_math.h"
#include "BLI_blenlib.h"
#include "BLI_rand.h"
#include "BLI_utildefines.h"

#include "BLT_translation.h"

#include "DNA_anim_types.h"
#include "DNA_curve_types.h"
#include "DNA_object_types.h"
#include "DNA_node_types.h"
#include "DNA_scene_types.h"
#include "DNA_screen_types.h"
#include "DNA_space_types.h"
#include "DNA_view3d_types.h"
#include "DNA_gpencil_types.h"

#include "BKE_context.h"
#include "BKE_curve.h"
#include "BKE_depsgraph.h"
#include "BKE_fcurve.h"
#include "BKE_global.h"
#include "BKE_gpencil.h"
#include "BKE_library.h"
#include "BKE_object.h"
#include "BKE_report.h"
#include "BKE_scene.h"
#include "BKE_screen.h"
#include "BKE_tracking.h"

#include "UI_interface.h"

#include "WM_api.h"
#include "WM_types.h"

#include "RNA_access.h"
#include "RNA_define.h"

#include "UI_resources.h"
#include "UI_view2d.h"

#include "ED_gpencil.h"
#include "ED_view3d.h"
#include "ED_clip.h"
#include "ED_keyframing.h"

#include "gpencil_intern.h"

/* ************************************************ */
/* Grease Pencil to Data Operator */

/* defines for possible modes */
enum {
	GP_STROKECONVERT_PATH = 1,
	GP_STROKECONVERT_CURVE,
	GP_STROKECONVERT_POLY,
};

/* Defines for possible timing modes */
enum {
	GP_STROKECONVERT_TIMING_NONE = 1,
	GP_STROKECONVERT_TIMING_LINEAR = 2,
	GP_STROKECONVERT_TIMING_FULL = 3,
	GP_STROKECONVERT_TIMING_CUSTOMGAP = 4,
};

/* RNA enum define */
static EnumPropertyItem prop_gpencil_convertmodes[] = {
	{GP_STROKECONVERT_PATH, "PATH", ICON_CURVE_PATH, "Path", "Animation path"},
	{GP_STROKECONVERT_CURVE, "CURVE", ICON_CURVE_BEZCURVE, "Bezier Curve", "Smooth Bezier curve"},
	{GP_STROKECONVERT_POLY, "POLY", ICON_MESH_DATA, "Polygon Curve", "Bezier curve with straight-line segments (vector handles)"},
	{0, NULL, 0, NULL, NULL}
};

static EnumPropertyItem prop_gpencil_convert_timingmodes_restricted[] = {
	{GP_STROKECONVERT_TIMING_NONE, "NONE", 0, "No Timing", "Ignore timing"},
	{GP_STROKECONVERT_TIMING_LINEAR, "LINEAR", 0, "Linear", "Simple linear timing"},
	{0, NULL, 0, NULL, NULL},
};

static EnumPropertyItem prop_gpencil_convert_timingmodes[] = {
	{GP_STROKECONVERT_TIMING_NONE, "NONE", 0, "No Timing", "Ignore timing"},
	{GP_STROKECONVERT_TIMING_LINEAR, "LINEAR", 0, "Linear", "Simple linear timing"},
	{GP_STROKECONVERT_TIMING_FULL, "FULL", 0, "Original", "Use the original timing, gaps included"},
	{GP_STROKECONVERT_TIMING_CUSTOMGAP, "CUSTOMGAP", 0, "Custom Gaps",
	                                    "Use the original timing, but with custom gap lengths (in frames)"},
	{0, NULL, 0, NULL, NULL},
};

static EnumPropertyItem *rna_GPConvert_mode_items(bContext *UNUSED(C), PointerRNA *ptr, PropertyRNA *UNUSED(prop),
                                                  bool *UNUSED(r_free))
{
	if (RNA_boolean_get(ptr, "use_timing_data")) {
		return prop_gpencil_convert_timingmodes;
	}
	return prop_gpencil_convert_timingmodes_restricted;
}

/* --- */

/* convert the coordinates from the given stroke point into 3d-coordinates
 *	- assumes that the active space is the 3D-View
 */
static void gp_strokepoint_convertcoords(
        bContext *C, bGPDlayer *gpl, bGPDstroke *gps, bGPDspoint *source_pt,
        float p3d[3], const rctf *subrect)
{
	Scene *scene = CTX_data_scene(C);
	View3D *v3d = CTX_wm_view3d(C);
	ARegion *ar = CTX_wm_region(C);
	bGPDspoint mypt, *pt;

	float diff_mat[4][4];
	pt = &mypt;

	/* calculate difference matrix if parent object */
	if (gpl->parent == NULL) {
		copy_v3_v3(&pt->x, &source_pt->x);
	}
	else {
		/* apply parent transform */
		float fpt[3];
		ED_gpencil_parent_location(gpl, diff_mat);
		mul_v3_m4v3(fpt, diff_mat, &source_pt->x);
		copy_v3_v3(&pt->x, fpt);
	}


	if (gps->flag & GP_STROKE_3DSPACE) {
		/* directly use 3d-coordinates */
		copy_v3_v3(p3d, &pt->x);
	}
	else {
		const float *fp = ED_view3d_cursor3d_get(scene, v3d);
		float mvalf[2];
		
		/* get screen coordinate */
		if (gps->flag & GP_STROKE_2DSPACE) {
			View2D *v2d = &ar->v2d;
			UI_view2d_view_to_region_fl(v2d, pt->x, pt->y, &mvalf[0], &mvalf[1]);
		}
		else {
			if (subrect) {
				mvalf[0] = (((float)pt->x / 100.0f) * BLI_rctf_size_x(subrect)) + subrect->xmin;
				mvalf[1] = (((float)pt->y / 100.0f) * BLI_rctf_size_y(subrect)) + subrect->ymin;
			}
			else {
				mvalf[0] = (float)pt->x / 100.0f * ar->winx;
				mvalf[1] = (float)pt->y / 100.0f * ar->winy;
			}
		}
		
		ED_view3d_win_to_3d(v3d, ar, fp, mvalf, p3d);
	}
}

/* --- */

/* temp struct for gp_stroke_path_animation() */
typedef struct tGpTimingData {
	/* Data set from operator settings */
	int mode;
	int frame_range; /* Number of frames evaluated for path animation */
	int start_frame, end_frame;
	bool realtime; /* Will overwrite end_frame in case of Original or CustomGap timing... */
	float gap_duration, gap_randomness; /* To be used with CustomGap mode*/
	int seed;
	
	/* Data set from points, used to compute final timing FCurve */
	int num_points, cur_point;
	
	/* Distances */
	float *dists;
	float tot_dist;
	
	/* Times */
	float *times; /* Note: Gap times will be negative! */
	float tot_time, gap_tot_time;
	double inittime;
	
	/* Only used during creation of dists & times lists. */
	float offset_time;
} tGpTimingData;

/* Init point buffers for timing data.
 * Note this assumes we only grow those arrays!
 */
static void gp_timing_data_set_nbr(tGpTimingData *gtd, const int nbr)
{
	float *tmp;
	
	BLI_assert(nbr > gtd->num_points);
	
	/* distances */
	tmp = gtd->dists;
	gtd->dists = MEM_callocN(sizeof(float) * nbr, __func__);
	if (tmp) {
		memcpy(gtd->dists, tmp, sizeof(float) * gtd->num_points);
		MEM_freeN(tmp);
	}
	
	/* times */
	tmp = gtd->times;
	gtd->times = MEM_callocN(sizeof(float) * nbr, __func__);
	if (tmp) {
		memcpy(gtd->times, tmp, sizeof(float) * gtd->num_points);
		MEM_freeN(tmp);
	}
	
	gtd->num_points = nbr;
}

/* add stroke point to timing buffers */
static void gp_timing_data_add_point(tGpTimingData *gtd, const double stroke_inittime, const float time,
                                     const float delta_dist)
{
	float delta_time = 0.0f;
	const int cur_point = gtd->cur_point;
	
	if (!cur_point) {
		/* Special case, first point, if time is not 0.0f we have to compensate! */
		gtd->offset_time = -time;
		gtd->times[cur_point] = 0.0f;
	}
	else if (time < 0.0f) {
		/* This is a gap, negative value! */
		gtd->times[cur_point] = -(((float)(stroke_inittime - gtd->inittime)) + time + gtd->offset_time);
		delta_time = -gtd->times[cur_point] - gtd->times[cur_point - 1];
		
		gtd->gap_tot_time += delta_time;
	}
	else {
		gtd->times[cur_point] = (((float)(stroke_inittime - gtd->inittime)) + time + gtd->offset_time);
		delta_time = gtd->times[cur_point] - fabsf(gtd->times[cur_point - 1]);
	}
	
	gtd->tot_time += delta_time;
	gtd->tot_dist += delta_dist;
	gtd->dists[cur_point] = gtd->tot_dist;
	
	gtd->cur_point++;
}

/* In frames! Binary search for FCurve keys have a threshold of 0.01, so we can't set
 * arbitrarily close points - this is esp. important with NoGaps mode!
 */
#define MIN_TIME_DELTA 0.02f

/* Loop over next points to find the end of the stroke, and compute */
static int gp_find_end_of_stroke_idx(tGpTimingData *gtd, RNG *rng, const int idx, const int nbr_gaps,
                                     int *nbr_done_gaps, const float tot_gaps_time, const float delta_time,
                                     float *next_delta_time)
{
	int j;
	
	for (j = idx + 1; j < gtd->num_points; j++) {
		if (gtd->times[j] < 0) {
			gtd->times[j] = -gtd->times[j];
			if (gtd->mode == GP_STROKECONVERT_TIMING_CUSTOMGAP) {
				/* In this mode, gap time between this stroke and the next should be 0 currently...
				 * So we have to compute its final duration!
				 */
				if (gtd->gap_randomness > 0.0f) {
					/* We want gaps that are in gtd->gap_duration +/- gtd->gap_randomness range,
					 * and which sum to exactly tot_gaps_time...
					 */
					int rem_gaps = nbr_gaps - (*nbr_done_gaps);
					if (rem_gaps < 2) {
						/* Last gap, just give remaining time! */
						*next_delta_time = tot_gaps_time;
					}
					else {
						float delta, min, max;
						
						/* This code ensures that if the first gaps have been shorter than average gap_duration,
						 * next gaps will tend to be longer (i.e. try to recover the lateness), and vice-versa!
						 */
						delta = delta_time - (gtd->gap_duration * (*nbr_done_gaps));
						
						/* Clamp min between [-gap_randomness, 0.0], with lower delta giving higher min */
						min = -gtd->gap_randomness - delta;
						CLAMP(min, -gtd->gap_randomness, 0.0f);
						
						/* Clamp max between [0.0, gap_randomness], with lower delta giving higher max */
						max = gtd->gap_randomness - delta;
						CLAMP(max, 0.0f, gtd->gap_randomness);
						*next_delta_time += gtd->gap_duration + (BLI_rng_get_float(rng) * (max - min)) + min;
					}
				}
				else {
					*next_delta_time += gtd->gap_duration;
				}
			}
			(*nbr_done_gaps)++;
			break;
		}
	}
	
	return j - 1;
}

static void gp_stroke_path_animation_preprocess_gaps(tGpTimingData *gtd, RNG *rng, int *nbr_gaps, float *tot_gaps_time)
{
	int i;
	float delta_time = 0.0f;
	
	for (i = 0; i < gtd->num_points; i++) {
		if (gtd->times[i] < 0 && i) {
			(*nbr_gaps)++;
			gtd->times[i] = -gtd->times[i] - delta_time;
			delta_time += gtd->times[i] - gtd->times[i - 1];
			gtd->times[i] = -gtd->times[i - 1]; /* Temp marker, values *have* to be different! */
		}
		else {
			gtd->times[i] -= delta_time;
		}
	}
	gtd->tot_time -= delta_time;
	
	*tot_gaps_time = (float)(*nbr_gaps) * gtd->gap_duration;
	gtd->tot_time += *tot_gaps_time;
	if (G.debug & G_DEBUG) {
		printf("%f, %f, %f, %d\n", gtd->tot_time, delta_time, *tot_gaps_time, *nbr_gaps);
	}
	if (gtd->gap_randomness > 0.0f) {
		BLI_rng_srandom(rng, gtd->seed);
	}
}

static void gp_stroke_path_animation_add_keyframes(ReportList *reports, PointerRNA ptr, PropertyRNA *prop, FCurve *fcu,
                                                   Curve *cu, tGpTimingData *gtd, RNG *rng, const float time_range,
                                                   const int nbr_gaps, const float tot_gaps_time)
{
	/* Use actual recorded timing! */
	const float time_start = (float)gtd->start_frame;
	
	float last_valid_time = 0.0f;
	int end_stroke_idx = -1, start_stroke_idx = 0;
	float end_stroke_time = 0.0f;
	
	/* CustomGaps specific */
	float delta_time = 0.0f, next_delta_time = 0.0f;
	int nbr_done_gaps = 0;
	
	int i;
	float cfra;
	
	/* This is a bit tricky, as:
	 * - We can't add arbitrarily close points on FCurve (in time).
	 * - We *must* have all "caps" points of all strokes in FCurve, as much as possible!
	 */
	for (i = 0; i < gtd->num_points; i++) {
		/* If new stroke... */
		if (i > end_stroke_idx) {
			start_stroke_idx = i;
			delta_time = next_delta_time;
			/* find end of that new stroke */
			end_stroke_idx = gp_find_end_of_stroke_idx(gtd, rng, i, nbr_gaps, &nbr_done_gaps,
			                                           tot_gaps_time, delta_time, &next_delta_time);
			/* This one should *never* be negative! */
			end_stroke_time = time_start + ((gtd->times[end_stroke_idx] + delta_time) / gtd->tot_time * time_range);
		}
		
		/* Simple proportional stuff... */
		cu->ctime = gtd->dists[i] / gtd->tot_dist * cu->pathlen;
		cfra = time_start + ((gtd->times[i] + delta_time) / gtd->tot_time * time_range);
		
		/* And now, the checks about timing... */
		if (i == start_stroke_idx) {
			/* If first point of a stroke, be sure it's enough ahead of last valid keyframe, and
			 * that the end point of the stroke is far enough!
			 * In case it is not, we keep the end point...
			 * Note that with CustomGaps mode, this is here we set the actual gap timing!
			 */
			if ((end_stroke_time - last_valid_time) > MIN_TIME_DELTA * 2) {
				if ((cfra - last_valid_time) < MIN_TIME_DELTA) {
					cfra = last_valid_time + MIN_TIME_DELTA;
				}
				insert_keyframe_direct(reports, ptr, prop, fcu, cfra, BEZT_KEYTYPE_KEYFRAME, INSERTKEY_FAST);
				last_valid_time = cfra;
			}
			else if (G.debug & G_DEBUG) {
				printf("\t Skipping start point %d, too close from end point %d\n", i, end_stroke_idx);
			}
		}
		else if (i == end_stroke_idx) {
			/* Always try to insert end point of a curve (should be safe enough, anyway...) */
			if ((cfra - last_valid_time) < MIN_TIME_DELTA) {
				cfra = last_valid_time + MIN_TIME_DELTA;
			}
			insert_keyframe_direct(reports, ptr, prop, fcu, cfra, BEZT_KEYTYPE_KEYFRAME, INSERTKEY_FAST);
			last_valid_time = cfra;
		}
		else {
			/* Else ("middle" point), we only insert it if it's far enough from last keyframe,
			 * and also far enough from (not yet added!) end_stroke keyframe!
			 */
			if ((cfra - last_valid_time) > MIN_TIME_DELTA && (end_stroke_time - cfra) > MIN_TIME_DELTA) {
				insert_keyframe_direct(reports, ptr, prop, fcu, cfra, BEZT_KEYTYPE_BREAKDOWN, INSERTKEY_FAST);
				last_valid_time = cfra;
			}
			else if (G.debug & G_DEBUG) {
				printf("\t Skipping \"middle\" point %d, too close from last added point or end point %d\n",
				       i, end_stroke_idx);
			}
		}
	}
}

static void gp_stroke_path_animation(bContext *C, ReportList *reports, Curve *cu, tGpTimingData *gtd)
{
	Scene *scene = CTX_data_scene(C);
	bAction *act;
	FCurve *fcu;
	PointerRNA ptr;
	PropertyRNA *prop = NULL;
	int nbr_gaps = 0, i;
	
	if (gtd->mode == GP_STROKECONVERT_TIMING_NONE)
		return;
	
	/* gap_duration and gap_randomness are in frames, but we need seconds!!! */
	gtd->gap_duration = FRA2TIME(gtd->gap_duration);
	gtd->gap_randomness = FRA2TIME(gtd->gap_randomness);
	
	/* Enable path! */
	cu->flag |= CU_PATH;
	cu->pathlen = gtd->frame_range;
	
	/* Get RNA pointer to read/write path time values */
	RNA_id_pointer_create((ID *)cu, &ptr);
	prop = RNA_struct_find_property(&ptr, "eval_time");
	
	/* Ensure we have an F-Curve to add keyframes to */
	act = verify_adt_action((ID *)cu, true);
	fcu = verify_fcurve(act, NULL, &ptr, "eval_time", 0, true);
	
	if (G.debug & G_DEBUG) {
		printf("%s: tot len: %f\t\ttot time: %f\n", __func__, gtd->tot_dist, gtd->tot_time);
		for (i = 0; i < gtd->num_points; i++) {
			printf("\tpoint %d:\t\tlen: %f\t\ttime: %f\n", i, gtd->dists[i], gtd->times[i]);
		}
	}
	
	if (gtd->mode == GP_STROKECONVERT_TIMING_LINEAR) {
		float cfra;
		
		/* Linear extrapolation! */
		fcu->extend = FCURVE_EXTRAPOLATE_LINEAR;
		
		cu->ctime = 0.0f;
		cfra = (float)gtd->start_frame;
		insert_keyframe_direct(reports, ptr, prop, fcu, cfra, BEZT_KEYTYPE_KEYFRAME, INSERTKEY_FAST);
		
		cu->ctime = cu->pathlen;
		if (gtd->realtime) {
			cfra += (float)TIME2FRA(gtd->tot_time); /* Seconds to frames */
		}
		else {
			cfra = (float)gtd->end_frame;
		}
		insert_keyframe_direct(reports, ptr, prop, fcu, cfra, BEZT_KEYTYPE_KEYFRAME, INSERTKEY_FAST);
	}
	else {
		/* Use actual recorded timing! */
		RNG *rng = BLI_rng_new(0);
		float time_range;
		
		/* CustomGaps specific */
		float tot_gaps_time = 0.0f;
		
		/* Pre-process gaps, in case we don't want to keep their original timing */
		if (gtd->mode == GP_STROKECONVERT_TIMING_CUSTOMGAP) {
			gp_stroke_path_animation_preprocess_gaps(gtd, rng, &nbr_gaps, &tot_gaps_time);
		}
		
		if (gtd->realtime) {
			time_range = (float)TIME2FRA(gtd->tot_time); /* Seconds to frames */
		}
		else {
			time_range = (float)(gtd->end_frame - gtd->start_frame);
		}
		
		if (G.debug & G_DEBUG) {
			printf("GP Stroke Path Conversion: Starting keying!\n");
		}
		
		gp_stroke_path_animation_add_keyframes(reports, ptr, prop, fcu, cu, gtd, rng, time_range,
		                                       nbr_gaps, tot_gaps_time);
		
		BLI_rng_free(rng);
	}
	
	/* As we used INSERTKEY_FAST mode, we need to recompute all curve's handles now */
	calchandles_fcurve(fcu);
	
	if (G.debug & G_DEBUG) {
		printf("%s: \ntot len: %f\t\ttot time: %f\n", __func__, gtd->tot_dist, gtd->tot_time);
		for (i = 0; i < gtd->num_points; i++) {
			printf("\tpoint %d:\t\tlen: %f\t\ttime: %f\n", i, gtd->dists[i], gtd->times[i]);
		}
		printf("\n\n");
	}
	
	WM_event_add_notifier(C, NC_ANIMATION | ND_KEYFRAME | NA_EDITED, NULL);
	
	/* send updates */
	DAG_id_tag_update(&cu->id, 0);
}

#undef MIN_TIME_DELTA

#define GAP_DFAC 0.01f
#define WIDTH_CORR_FAC 0.1f
#define BEZT_HANDLE_FAC 0.3f

/* convert stroke to 3d path */

/* helper */
static void gp_stroke_to_path_add_point(tGpTimingData *gtd, BPoint *bp, const float p[3], const float prev_p[3],
                                        const bool do_gtd, const double inittime, const float time,
                                        const float width, const float rad_fac, float minmax_weights[2])
{
	copy_v3_v3(bp->vec, p);
	bp->vec[3] = 1.0f;
	
	/* set settings */
	bp->f1 = SELECT;
	bp->radius = width * rad_fac;
	bp->weight = width;
	CLAMP(bp->weight, 0.0f, 1.0f);
	if (bp->weight < minmax_weights[0]) {
		minmax_weights[0] = bp->weight;
	}
	else if (bp->weight > minmax_weights[1]) {
		minmax_weights[1] = bp->weight;
	}
	
	/* Update timing data */
	if (do_gtd) {
		gp_timing_data_add_point(gtd, inittime, time, len_v3v3(prev_p, p));
	}
}

static void gp_stroke_to_path(bContext *C, bGPDlayer *gpl, bGPDstroke *gps, Curve *cu, rctf *subrect, Nurb **curnu,
                              float minmax_weights[2], const float rad_fac, bool stitch, const bool add_start_point,
                              const bool add_end_point, tGpTimingData *gtd)
{
	bGPDspoint *pt;
	Nurb *nu = (curnu) ? *curnu : NULL;
	BPoint *bp, *prev_bp = NULL;
	const bool do_gtd = (gtd->mode != GP_STROKECONVERT_TIMING_NONE);
	const int add_start_end_points = (add_start_point ? 1 : 0) + (add_end_point ? 1 : 0);
	int i, old_nbp = 0;
	
	/* create new 'nurb' or extend current one within the curve */
	if (nu) {
		old_nbp = nu->pntsu;

		/* If stitch, the first point of this stroke is already present in current nu.
		 * Else, we have to add two additional points to make the zero-radius link between strokes.
		 */
		BKE_nurb_points_add(nu, gps->totpoints + (stitch ? -1 : 2) + add_start_end_points);
	}
	else {
		nu = (Nurb *)MEM_callocN(sizeof(Nurb), "gpstroke_to_path(nurb)");
		
		nu->pntsu = gps->totpoints + add_start_end_points;
		nu->pntsv = 1;
		nu->orderu = 2; /* point-to-point! */
		nu->type = CU_NURBS;
		nu->flagu = CU_NURB_ENDPOINT;
		nu->resolu = cu->resolu;
		nu->resolv = cu->resolv;
		nu->knotsu = NULL;
		
		nu->bp = (BPoint *)MEM_callocN(sizeof(BPoint) * nu->pntsu, "bpoints");
		
		stitch = false; /* Security! */
	}
	
	if (do_gtd) {
		gp_timing_data_set_nbr(gtd, nu->pntsu);
	}
	
	/* If needed, make the link between both strokes with two zero-radius additional points */
	/* About "zero-radius" point interpolations:
	 * - If we have at least two points in current curve (most common case), we linearly extrapolate
	 *   the last segment to get the first point (p1) position and timing.
	 * - If we do not have those (quite odd, but may happen), we linearly interpolate the last point
	 *   with the first point of the current stroke.
	 * The same goes for the second point, first segment of the current stroke is "negatively" extrapolated
	 * if it exists, else (if the stroke is a single point), linear interpolation with last curve point...
	 */
	if (curnu && !stitch && old_nbp) {
		float p1[3], p2[3], p[3], next_p[3];
		float dt1 = 0.0f, dt2 = 0.0f;
		
		BLI_assert(gps->prev != NULL);
		
		prev_bp = NULL;
		if ((old_nbp > 1) && (gps->prev->totpoints > 1)) {
			/* Only use last curve segment if previous stroke was not a single-point one! */
			prev_bp = &nu->bp[old_nbp - 2];
		}
		bp = &nu->bp[old_nbp - 1];
		
		/* First point */
		gp_strokepoint_convertcoords(C, gpl, gps, gps->points, p, subrect);
		if (prev_bp) {
			interp_v3_v3v3(p1, bp->vec, prev_bp->vec, -GAP_DFAC);
			if (do_gtd) {
				const int idx = gps->prev->totpoints - 1;
				dt1 = interpf(gps->prev->points[idx - 1].time, gps->prev->points[idx].time, -GAP_DFAC);
			}
		}
		else {
			interp_v3_v3v3(p1, bp->vec, p, GAP_DFAC);
			if (do_gtd) {
				dt1 = interpf(gps->inittime - gps->prev->inittime, 0.0f, GAP_DFAC);
			}
		}
		bp++;
		gp_stroke_to_path_add_point(gtd, bp, p1, (bp - 1)->vec, do_gtd, gps->prev->inittime, dt1,
		                            0.0f, rad_fac, minmax_weights);
		
		/* Second point */
		/* Note dt2 is always negative, which marks the gap. */
		if (gps->totpoints > 1) {
			gp_strokepoint_convertcoords(C, gpl, gps, gps->points + 1, next_p, subrect);
			interp_v3_v3v3(p2, p, next_p, -GAP_DFAC);
			if (do_gtd) {
				dt2 = interpf(gps->points[1].time, gps->points[0].time, -GAP_DFAC);
			}
		}
		else {
			interp_v3_v3v3(p2, p, bp->vec, GAP_DFAC);
			if (do_gtd) {
				dt2 = interpf(gps->prev->inittime - gps->inittime, 0.0f, GAP_DFAC);
			}
		}
		bp++;
		gp_stroke_to_path_add_point(gtd, bp, p2, p1, do_gtd, gps->inittime, dt2, 0.0f, rad_fac, minmax_weights);
		
		old_nbp += 2;
	}
	else if (add_start_point) {
		float p[3], next_p[3];
		float dt = 0.0f;
		
		gp_strokepoint_convertcoords(C, gpl, gps, gps->points, p, subrect);
		if (gps->totpoints > 1) {
			gp_strokepoint_convertcoords(C, gpl, gps, gps->points + 1, next_p, subrect);
			interp_v3_v3v3(p, p, next_p, -GAP_DFAC);
			if (do_gtd) {
				dt = interpf(gps->points[1].time, gps->points[0].time, -GAP_DFAC);
			}
		}
		else {
			p[0] -= GAP_DFAC;  /* Rather arbitrary... */
			dt = -GAP_DFAC;  /* Rather arbitrary too! */
		}
		bp = &nu->bp[old_nbp];
		/* Note we can't give anything else than 0.0 as time here, since a negative one (which would be expected value)
		 * would not work (it would be *before* gtd->inittime, which is not supported currently).
		 */
		gp_stroke_to_path_add_point(gtd, bp, p, p, do_gtd, gps->inittime, dt, 0.0f, rad_fac, minmax_weights);
		
		old_nbp++;
	}
	
	if (old_nbp) {
		prev_bp = &nu->bp[old_nbp - 1];
	}
	
	/* add points */
	for (i = (stitch) ? 1 : 0, pt = &gps->points[(stitch) ? 1 : 0], bp = &nu->bp[old_nbp];
	     i < gps->totpoints;
	     i++, pt++, bp++)
	{
		float p[3];
		float width = pt->pressure * (gps->thickness + gpl->thickness) * WIDTH_CORR_FAC;
		
		/* get coordinates to add at */
		gp_strokepoint_convertcoords(C, gpl, gps, pt, p, subrect);
		
		gp_stroke_to_path_add_point(gtd, bp, p, (prev_bp) ? prev_bp->vec : p, do_gtd, gps->inittime, pt->time,
		                            width, rad_fac, minmax_weights);
		
		prev_bp = bp;
	}

	if (add_end_point) {
		float p[3];
		float dt = 0.0f;
		
		if (gps->totpoints > 1) {
			interp_v3_v3v3(p, prev_bp->vec, (prev_bp - 1)->vec, -GAP_DFAC);
			if (do_gtd) {
				const int idx = gps->totpoints - 1;
				dt = interpf(gps->points[idx - 1].time, gps->points[idx].time, -GAP_DFAC);
			}
		}
		else {
			copy_v3_v3(p, prev_bp->vec);
			p[0] += GAP_DFAC;  /* Rather arbitrary... */
			dt = GAP_DFAC;  /* Rather arbitrary too! */
		}
		/* Note bp has already been incremented in main loop above, so it points to the right place. */
		gp_stroke_to_path_add_point(gtd, bp, p, prev_bp->vec, do_gtd, gps->inittime, dt, 0.0f, rad_fac, minmax_weights);
	}
	
	/* add nurb to curve */
	if (!curnu || !*curnu) {
		BLI_addtail(&cu->nurb, nu);
	}
	if (curnu) {
		*curnu = nu;
	}
	
	BKE_nurb_knot_calc_u(nu);
}

/* convert stroke to 3d bezier */

/* helper */
static void gp_stroke_to_bezier_add_point(tGpTimingData *gtd, BezTriple *bezt,
                                          const float p[3], const float h1[3], const float h2[3], const float prev_p[3],
                                          const bool do_gtd, const double inittime, const float time,
                                          const float width, const float rad_fac, float minmax_weights[2])
{
	copy_v3_v3(bezt->vec[0], h1);
	copy_v3_v3(bezt->vec[1], p);
	copy_v3_v3(bezt->vec[2], h2);
	
	/* set settings */
	bezt->h1 = bezt->h2 = HD_FREE;
	bezt->f1 = bezt->f2 = bezt->f3 = SELECT;
	bezt->radius = width * rad_fac;
	bezt->weight = width;
	CLAMP(bezt->weight, 0.0f, 1.0f);
	if (bezt->weight < minmax_weights[0]) {
		minmax_weights[0] = bezt->weight;
	}
	else if (bezt->weight > minmax_weights[1]) {
		minmax_weights[1] = bezt->weight;
	}
	
	/* Update timing data */
	if (do_gtd) {
		gp_timing_data_add_point(gtd, inittime, time, len_v3v3(prev_p, p));
	}
}

static void gp_stroke_to_bezier(bContext *C, bGPDlayer *gpl, bGPDstroke *gps, Curve *cu, rctf *subrect, Nurb **curnu,
                                float minmax_weights[2], const float rad_fac, bool stitch, const bool add_start_point,
                                const bool add_end_point, tGpTimingData *gtd)
{
	bGPDspoint *pt;
	Nurb *nu = (curnu) ? *curnu : NULL;
	BezTriple *bezt, *prev_bezt = NULL;
	int i, tot, old_nbezt = 0;
	const int add_start_end_points = (add_start_point ? 1 : 0) + (add_end_point ? 1 : 0);
	float p3d_cur[3], p3d_prev[3], p3d_next[3], h1[3], h2[3];
	const bool do_gtd = (gtd->mode != GP_STROKECONVERT_TIMING_NONE);
	
	/* create new 'nurb' or extend current one within the curve */
	if (nu) {
		old_nbezt = nu->pntsu;
		/* If we do stitch, first point of current stroke is assumed the same as last point of previous stroke,
		 * so no need to add it.
		 * If no stitch, we want to add two additional points to make a "zero-radius" link between both strokes.
		 */
		BKE_nurb_bezierPoints_add(nu, gps->totpoints + ((stitch) ? -1 : 2) + add_start_end_points);
	}
	else {
		nu = (Nurb *)MEM_callocN(sizeof(Nurb), "gpstroke_to_bezier(nurb)");
		
		nu->pntsu = gps->totpoints + add_start_end_points;
		nu->resolu = 12;
		nu->resolv = 12;
		nu->type = CU_BEZIER;
		nu->bezt = (BezTriple *)MEM_callocN(sizeof(BezTriple) * nu->pntsu, "bezts");
		
		stitch = false; /* Security! */
	}
	
	if (do_gtd) {
		gp_timing_data_set_nbr(gtd, nu->pntsu);
	}
	
	tot = gps->totpoints;
	
	/* get initial coordinates */
	pt = gps->points;
	if (tot) {
		gp_strokepoint_convertcoords(C, gpl, gps, pt, (stitch) ? p3d_prev : p3d_cur, subrect);
		if (tot > 1) {
			gp_strokepoint_convertcoords(C, gpl, gps, pt + 1, (stitch) ? p3d_cur : p3d_next, subrect);
		}
		if (stitch && tot > 2) {
			gp_strokepoint_convertcoords(C, gpl, gps, pt + 2, p3d_next, subrect);
		}
	}
	
	/* If needed, make the link between both strokes with two zero-radius additional points */
	if (curnu && old_nbezt) {
		BLI_assert(gps->prev != NULL);
		
		/* Update last point's second handle */
		if (stitch) {
			bezt = &nu->bezt[old_nbezt - 1];
			interp_v3_v3v3(h2, bezt->vec[1], p3d_cur, BEZT_HANDLE_FAC);
			copy_v3_v3(bezt->vec[2], h2);
			pt++;
		}
		
		/* Create "link points" */
		/* About "zero-radius" point interpolations:
		 * - If we have at least two points in current curve (most common case), we linearly extrapolate
		 *   the last segment to get the first point (p1) position and timing.
		 * - If we do not have those (quite odd, but may happen), we linearly interpolate the last point
		 *   with the first point of the current stroke.
		 * The same goes for the second point, first segment of the current stroke is "negatively" extrapolated
		 * if it exists, else (if the stroke is a single point), linear interpolation with last curve point...
		 */
		else {
			float p1[3], p2[3];
			float dt1 = 0.0f, dt2 = 0.0f;
			
			prev_bezt = NULL;
			if ((old_nbezt > 1) && (gps->prev->totpoints > 1)) {
				/* Only use last curve segment if previous stroke was not a single-point one! */
				prev_bezt = &nu->bezt[old_nbezt - 2];
			}
			bezt = &nu->bezt[old_nbezt - 1];
			
			/* First point */
			if (prev_bezt) {
				interp_v3_v3v3(p1, prev_bezt->vec[1], bezt->vec[1], 1.0f + GAP_DFAC);
				if (do_gtd) {
					const int idx = gps->prev->totpoints - 1;
					dt1 = interpf(gps->prev->points[idx - 1].time, gps->prev->points[idx].time, -GAP_DFAC);
				}
			}
			else {
				interp_v3_v3v3(p1, bezt->vec[1], p3d_cur, GAP_DFAC);
				if (do_gtd) {
					dt1 = interpf(gps->inittime - gps->prev->inittime, 0.0f, GAP_DFAC);
				}
			}
			
			/* Second point */
			/* Note dt2 is always negative, which marks the gap. */
			if (tot > 1) {
				interp_v3_v3v3(p2, p3d_cur, p3d_next, -GAP_DFAC);
				if (do_gtd) {
					dt2 = interpf(gps->points[1].time, gps->points[0].time, -GAP_DFAC);
				}
			}
			else {
				interp_v3_v3v3(p2, p3d_cur, bezt->vec[1], GAP_DFAC);
				if (do_gtd) {
					dt2 = interpf(gps->prev->inittime - gps->inittime, 0.0f, GAP_DFAC);
				}
			}
			
			/* Second handle of last point of previous stroke. */
			interp_v3_v3v3(h2, bezt->vec[1], p1, BEZT_HANDLE_FAC);
			copy_v3_v3(bezt->vec[2], h2);
			
			/* First point */
			interp_v3_v3v3(h1, p1, bezt->vec[1], BEZT_HANDLE_FAC);
			interp_v3_v3v3(h2, p1, p2, BEZT_HANDLE_FAC);
			bezt++;
			gp_stroke_to_bezier_add_point(gtd, bezt, p1, h1, h2, (bezt - 1)->vec[1], do_gtd, gps->prev->inittime, dt1,
			                              0.0f, rad_fac, minmax_weights);
			
			/* Second point */
			interp_v3_v3v3(h1, p2, p1, BEZT_HANDLE_FAC);
			interp_v3_v3v3(h2, p2, p3d_cur, BEZT_HANDLE_FAC);
			bezt++;
			gp_stroke_to_bezier_add_point(gtd, bezt, p2, h1, h2, p1, do_gtd, gps->inittime, dt2,
			                              0.0f, rad_fac, minmax_weights);
			
			old_nbezt += 2;
			copy_v3_v3(p3d_prev, p2);
		}
	}
	else if (add_start_point) {
		float p[3];
		float dt = 0.0f;
		
		if (gps->totpoints > 1) {
			interp_v3_v3v3(p, p3d_cur, p3d_next, -GAP_DFAC);
			if (do_gtd) {
				dt = interpf(gps->points[1].time, gps->points[0].time, -GAP_DFAC);
			}
		}
		else {
			copy_v3_v3(p, p3d_cur);
			p[0] -= GAP_DFAC;  /* Rather arbitrary... */
			dt = -GAP_DFAC;  /* Rather arbitrary too! */
		}
		interp_v3_v3v3(h1, p, p3d_cur, -BEZT_HANDLE_FAC);
		interp_v3_v3v3(h2, p, p3d_cur, BEZT_HANDLE_FAC);
		bezt = &nu->bezt[old_nbezt];
		gp_stroke_to_bezier_add_point(gtd, bezt, p, h1, h2, p, do_gtd, gps->inittime, dt,
		                              0.0f, rad_fac, minmax_weights);
		
		old_nbezt++;
		copy_v3_v3(p3d_prev, p);
	}
	
	if (old_nbezt) {
		prev_bezt = &nu->bezt[old_nbezt - 1];
	}
	
	/* add points */
	for (i = stitch ? 1 : 0, bezt = &nu->bezt[old_nbezt]; i < tot; i++, pt++, bezt++) {
		float width = pt->pressure * (gps->thickness + gpl->thickness) * WIDTH_CORR_FAC;
		
		if (i || old_nbezt) {
			interp_v3_v3v3(h1, p3d_cur, p3d_prev, BEZT_HANDLE_FAC);
		}
		else {
			interp_v3_v3v3(h1, p3d_cur, p3d_next, -BEZT_HANDLE_FAC);
		}
		
		if (i < tot - 1) {
			interp_v3_v3v3(h2, p3d_cur, p3d_next, BEZT_HANDLE_FAC);
		}
		else {
			interp_v3_v3v3(h2, p3d_cur, p3d_prev, -BEZT_HANDLE_FAC);
		}
		
		gp_stroke_to_bezier_add_point(gtd, bezt, p3d_cur, h1, h2, prev_bezt ? prev_bezt->vec[1] : p3d_cur,
		                              do_gtd, gps->inittime, pt->time, width, rad_fac, minmax_weights);
		
		/* shift coord vects */
		copy_v3_v3(p3d_prev, p3d_cur);
		copy_v3_v3(p3d_cur, p3d_next);
		
		if (i + 2 < tot) {
			gp_strokepoint_convertcoords(C, gpl, gps, pt + 2, p3d_next, subrect);
		}
		
		prev_bezt = bezt;
	}

	if (add_end_point) {
		float p[3];
		float dt = 0.0f;
		
		if (gps->totpoints > 1) {
			interp_v3_v3v3(p, prev_bezt->vec[1], (prev_bezt - 1)->vec[1], -GAP_DFAC);
			if (do_gtd) {
				const int idx = gps->totpoints - 1;
				dt = interpf(gps->points[idx - 1].time, gps->points[idx].time, -GAP_DFAC);
			}
		}
		else {
			copy_v3_v3(p, prev_bezt->vec[1]);
			p[0] += GAP_DFAC;  /* Rather arbitrary... */
			dt = GAP_DFAC;  /* Rather arbitrary too! */
		}
		
		/* Second handle of last point of this stroke. */
		interp_v3_v3v3(h2, prev_bezt->vec[1], p, BEZT_HANDLE_FAC);
		copy_v3_v3(prev_bezt->vec[2], h2);
		
		/* The end point */
		interp_v3_v3v3(h1, p, prev_bezt->vec[1], BEZT_HANDLE_FAC);
		interp_v3_v3v3(h2, p, prev_bezt->vec[1], -BEZT_HANDLE_FAC);
		/* Note bezt has already been incremented in main loop above, so it points to the right place. */
		gp_stroke_to_bezier_add_point(gtd, bezt, p, h1, h2, prev_bezt->vec[1], do_gtd, gps->inittime, dt,
		                              0.0f, rad_fac, minmax_weights);
	}
	
	/* must calculate handles or else we crash */
	BKE_nurb_handles_calc(nu);
	
	if (!curnu || !*curnu) {
		BLI_addtail(&cu->nurb, nu);
	}
	if (curnu) {
		*curnu = nu;
	}
}

#undef GAP_DFAC
#undef WIDTH_CORR_FAC
#undef BEZT_HANDLE_FAC

static void gp_stroke_finalize_curve_endpoints(Curve *cu)
{
	/* start */
	Nurb *nu = cu->nurb.first;
	int i = 0;
	if (nu->bezt) {
		BezTriple *bezt = nu->bezt;
		if (bezt) {
			bezt[i].weight = bezt[i].radius = 0.0f;
		}
	}
	else if (nu->bp) {
		BPoint *bp = nu->bp;
		if (bp) {
			bp[i].weight = bp[i].radius = 0.0f;
		}
	}
	
	/* end */
	nu = cu->nurb.last;
	i = nu->pntsu - 1;
	if (nu->bezt) {
		BezTriple *bezt = nu->bezt;
		if (bezt) {
			bezt[i].weight = bezt[i].radius = 0.0f;
		}
	}
	else if (nu->bp) {
		BPoint *bp = nu->bp;
		if (bp) {
			bp[i].weight = bp[i].radius = 0.0f;
		}
	}
}

static void gp_stroke_norm_curve_weights(Curve *cu, const float minmax_weights[2])
{
	Nurb *nu;
	const float delta = minmax_weights[0];
	float fac;
	int i;
	
	/* when delta == minmax_weights[0] == minmax_weights[1], we get div by zero [#35686] */
	if (IS_EQF(delta, minmax_weights[1]))
		fac = 1.0f;
	else
		fac = 1.0f / (minmax_weights[1] - delta);
	
	for (nu = cu->nurb.first; nu; nu = nu->next) {
		if (nu->bezt) {
			BezTriple *bezt = nu->bezt;
			for (i = 0; i < nu->pntsu; i++, bezt++) {
				bezt->weight = (bezt->weight - delta) * fac;
			}
		}
		else if (nu->bp) {
			BPoint *bp = nu->bp;
			for (i = 0; i < nu->pntsu; i++, bp++) {
				bp->weight = (bp->weight - delta) * fac;
			}
		}
	}
}

static int gp_camera_view_subrect(bContext *C, rctf *subrect)
{
	View3D *v3d = CTX_wm_view3d(C);
	ARegion *ar = CTX_wm_region(C);
	
	if (v3d) {
		RegionView3D *rv3d = ar->regiondata;
		
		/* for camera view set the subrect */
		if (rv3d->persp == RV3D_CAMOB) {
			Scene *scene = CTX_data_scene(C);
			ED_view3d_calc_camera_border(scene, ar, v3d, rv3d, subrect, true); /* no shift */
			return 1;
		}
	}
	
	return 0;
}

/* convert a given grease-pencil layer to a 3d-curve representation (using current view if appropriate) */
static void gp_layer_to_curve(bContext *C, ReportList *reports, bGPdata *gpd, bGPDlayer *gpl, const int mode,
                              const bool norm_weights, const float rad_fac, const bool link_strokes, tGpTimingData *gtd)
{
	struct Main *bmain = CTX_data_main(C);
	View3D *v3d = CTX_wm_view3d(C);  /* may be NULL */
	Scene *scene = CTX_data_scene(C);
	bGPDframe *gpf = BKE_gpencil_layer_getframe(gpl, CFRA, 0);
	bGPDstroke *gps, *prev_gps = NULL;
	Object *ob;
	Curve *cu;
	Nurb *nu = NULL;
	Base *base_orig = BASACT, *base_new = NULL;
	float minmax_weights[2] = {1.0f, 0.0f};
	
	/* camera framing */
	rctf subrect, *subrect_ptr = NULL;
	
	/* error checking */
	if (ELEM(NULL, gpd, gpl, gpf))
		return;
	
	/* only convert if there are any strokes on this layer's frame to convert */
	if (BLI_listbase_is_empty(&gpf->strokes))
		return;
	
	/* initialize camera framing */
	if (gp_camera_view_subrect(C, &subrect)) {
		subrect_ptr = &subrect;
	}
	
	/* init the curve object (remove rotation and get curve data from it)
	 *	- must clear transforms set on object, as those skew our results
	 */
	ob = BKE_object_add_only_object(bmain, OB_CURVE, gpl->info);
	cu = ob->data = BKE_curve_add(bmain, gpl->info, OB_CURVE);
	base_new = BKE_scene_base_add(scene, ob);
	
	cu->flag |= CU_3D;
	
	gtd->inittime = ((bGPDstroke *)gpf->strokes.first)->inittime;
	
	/* add points to curve */
	for (gps = gpf->strokes.first; gps; gps = gps->next) {
		const bool add_start_point = (link_strokes && !(prev_gps));
		const bool add_end_point = (link_strokes && !(gps->next));
		
		/* Detect new strokes created because of GP_STROKE_BUFFER_MAX reached, and stitch them to previous one. */
		bool stitch = false;
		if (prev_gps) {
			bGPDspoint *pt1 = &prev_gps->points[prev_gps->totpoints - 1];
			bGPDspoint *pt2 = &gps->points[0];
			
			if ((pt1->x == pt2->x) && (pt1->y == pt2->y)) {
				stitch = true;
			}
		}
		
		/* Decide whether we connect this stroke to previous one */
		if (!(stitch || link_strokes)) {
			nu = NULL;
		}
		
		switch (mode) {
			case GP_STROKECONVERT_PATH:
				gp_stroke_to_path(C, gpl, gps, cu, subrect_ptr, &nu, minmax_weights, rad_fac, stitch,
				                  add_start_point, add_end_point, gtd);
				break;
			case GP_STROKECONVERT_CURVE:
			case GP_STROKECONVERT_POLY:  /* convert after */
				gp_stroke_to_bezier(C, gpl, gps, cu, subrect_ptr, &nu, minmax_weights, rad_fac, stitch,
				                    add_start_point, add_end_point, gtd);
				break;
			default:
				BLI_assert(!"invalid mode");
				break;
		}
		prev_gps = gps;
	}
	
	/* If link_strokes, be sure first and last points have a zero weight/size! */
	if (link_strokes) {
		gp_stroke_finalize_curve_endpoints(cu);
	}
	
	/* Update curve's weights, if needed */
	if (norm_weights && ((minmax_weights[0] > 0.0f) || (minmax_weights[1] < 1.0f))) {
		gp_stroke_norm_curve_weights(cu, minmax_weights);
	}
	
	/* Create the path animation, if needed */
	gp_stroke_path_animation(C, reports, cu, gtd);
	
	if (mode == GP_STROKECONVERT_POLY) {
		for (nu = cu->nurb.first; nu; nu = nu->next) {
			BKE_nurb_type_convert(nu, CU_POLY, false);
		}
	}
	
	/* set the layer and select */
	base_new->lay  = ob->lay  = base_orig ? base_orig->lay : BKE_screen_view3d_layer_active(v3d, scene);
	base_new->flag = ob->flag = base_new->flag | SELECT;
}

/* --- */

/* Check a GP layer has valid timing data! Else, most timing options are hidden in the operator.
 * op may be NULL.
 */
static bool gp_convert_check_has_valid_timing(bContext *C, bGPDlayer *gpl, wmOperator *op)
{
	Scene *scene = CTX_data_scene(C);
	bGPDframe *gpf = NULL;
	bGPDstroke *gps = NULL;
	bGPDspoint *pt;
	double base_time, cur_time, prev_time = -1.0;
	int i;
	bool valid = true;
	
	if (!gpl || !(gpf = BKE_gpencil_layer_getframe(gpl, CFRA, 0)) || !(gps = gpf->strokes.first))
		return false;
	
	do {
		base_time = cur_time = gps->inittime;
		if (cur_time <= prev_time) {
			valid = false;
			break;
		}
		
		prev_time = cur_time;
		for (i = 0, pt = gps->points; i < gps->totpoints; i++, pt++) {
			cur_time = base_time + (double)pt->time;
			/* First point of a stroke should have the same time as stroke's inittime,
			 * so it's the only case where equality is allowed!
			 */
			if ((i && cur_time <= prev_time) || (cur_time < prev_time)) {
				valid = false;
				break;
			}
			prev_time = cur_time;
		}
		
		if (!valid) {
			break;
		}
	} while ((gps = gps->next));
	
	if (op) {
		RNA_boolean_set(op->ptr, "use_timing_data", valid);
	}
	return valid;
}

/* Check end_frame is always > start frame! */
static void gp_convert_set_end_frame(struct Main *UNUSED(main), struct Scene *UNUSED(scene), struct PointerRNA *ptr)
{
	int start_frame = RNA_int_get(ptr, "start_frame");
	int end_frame = RNA_int_get(ptr, "end_frame");
	
	if (end_frame <= start_frame) {
		RNA_int_set(ptr, "end_frame", start_frame + 1);
	}
}

static int gp_convert_poll(bContext *C)
{
	bGPdata *gpd = ED_gpencil_data_get_active(C);
	bGPDlayer *gpl = NULL;
	bGPDframe *gpf = NULL;
	ScrArea *sa = CTX_wm_area(C);
	Scene *scene = CTX_data_scene(C);
	
	/* only if the current view is 3D View, if there's valid data (i.e. at least one stroke!),
	 * and if we are not in edit mode!
	 */
	return ((sa && sa->spacetype == SPACE_VIEW3D) &&
	        (gpl = BKE_gpencil_layer_getactive(gpd)) &&
	        (gpf = BKE_gpencil_layer_getframe(gpl, CFRA, 0)) &&
	        (gpf->strokes.first) &&
	        (scene->obedit == NULL));
}

static int gp_convert_layer_exec(bContext *C, wmOperator *op)
{
	PropertyRNA *prop = RNA_struct_find_property(op->ptr, "use_timing_data");
	bGPdata *gpd = ED_gpencil_data_get_active(C);
	bGPDlayer *gpl = BKE_gpencil_layer_getactive(gpd);
	Scene *scene = CTX_data_scene(C);
	const int mode = RNA_enum_get(op->ptr, "type");
	const bool norm_weights = RNA_boolean_get(op->ptr, "use_normalize_weights");
	const float rad_fac = RNA_float_get(op->ptr, "radius_multiplier");
	const bool link_strokes = RNA_boolean_get(op->ptr, "use_link_strokes");
	bool valid_timing;
	tGpTimingData gtd;
	
	/* check if there's data to work with */
	if (gpd == NULL) {
		BKE_report(op->reports, RPT_ERROR, "No Grease Pencil data to work on");
		return OPERATOR_CANCELLED;
	}
	
	if (!RNA_property_is_set(op->ptr, prop) && !gp_convert_check_has_valid_timing(C, gpl, op)) {
		BKE_report(op->reports, RPT_WARNING,
		           "Current Grease Pencil strokes have no valid timing data, most timing options will be hidden!");
	}
	valid_timing = RNA_property_boolean_get(op->ptr, prop);
	
	gtd.mode = RNA_enum_get(op->ptr, "timing_mode");
	/* Check for illegal timing mode! */
	if (!valid_timing && !ELEM(gtd.mode, GP_STROKECONVERT_TIMING_NONE, GP_STROKECONVERT_TIMING_LINEAR)) {
		gtd.mode = GP_STROKECONVERT_TIMING_LINEAR;
		RNA_enum_set(op->ptr, "timing_mode", gtd.mode);
	}
	if (!link_strokes) {
		gtd.mode = GP_STROKECONVERT_TIMING_NONE;
	}
	
	/* grab all relevant settings */
	gtd.frame_range = RNA_int_get(op->ptr, "frame_range");
	gtd.start_frame = RNA_int_get(op->ptr, "start_frame");
	gtd.realtime = valid_timing ? RNA_boolean_get(op->ptr, "use_realtime") : false;
	gtd.end_frame = RNA_int_get(op->ptr, "end_frame");
	gtd.gap_duration = RNA_float_get(op->ptr, "gap_duration");
	gtd.gap_randomness = RNA_float_get(op->ptr, "gap_randomness");
	gtd.gap_randomness = min_ff(gtd.gap_randomness, gtd.gap_duration);
	gtd.seed = RNA_int_get(op->ptr, "seed");
	gtd.num_points = gtd.cur_point = 0;
	gtd.dists = gtd.times = NULL;
	gtd.tot_dist = gtd.tot_time = gtd.gap_tot_time = 0.0f;
	gtd.inittime = 0.0;
	gtd.offset_time = 0.0f;
	
	/* perform conversion */
	gp_layer_to_curve(C, op->reports, gpd, gpl, mode, norm_weights, rad_fac, link_strokes, &gtd);
	
	/* free temp memory */
	if (gtd.dists) {
		MEM_freeN(gtd.dists);
		gtd.dists = NULL;
	}
	if (gtd.times) {
		MEM_freeN(gtd.times);
		gtd.times = NULL;
	}
	
	/* notifiers */
	WM_event_add_notifier(C, NC_OBJECT | NA_ADDED, NULL);
	WM_event_add_notifier(C, NC_SCENE | ND_OB_ACTIVE, scene);
	
	/* done */
	return OPERATOR_FINISHED;
}

static bool gp_convert_draw_check_prop(PointerRNA *ptr, PropertyRNA *prop)
{
	const char *prop_id = RNA_property_identifier(prop);
	const bool link_strokes = RNA_boolean_get(ptr, "use_link_strokes");
	int timing_mode = RNA_enum_get(ptr, "timing_mode");
	bool realtime = RNA_boolean_get(ptr, "use_realtime");
	float gap_duration = RNA_float_get(ptr, "gap_duration");
	float gap_randomness = RNA_float_get(ptr, "gap_randomness");
	const bool valid_timing = RNA_boolean_get(ptr, "use_timing_data");
	
	/* Always show those props */
	if (STREQ(prop_id, "type") ||
	    STREQ(prop_id, "use_normalize_weights") ||
	    STREQ(prop_id, "radius_multiplier") ||
	    STREQ(prop_id, "use_link_strokes"))
	{
		return true;
	}
	
	/* Never show this prop */
	if (STREQ(prop_id, "use_timing_data"))
		return false;
	
	if (link_strokes) {
		/* Only show when link_stroke is true */
		if (STREQ(prop_id, "timing_mode"))
			return true;
		
		if (timing_mode != GP_STROKECONVERT_TIMING_NONE) {
			/* Only show when link_stroke is true and stroke timing is enabled */
			if (STREQ(prop_id, "frame_range") ||
			    STREQ(prop_id, "start_frame"))
			{
				return true;
			}
			
			/* Only show if we have valid timing data! */
			if (valid_timing && STREQ(prop_id, "use_realtime"))
				return true;
			
			/* Only show if realtime or valid_timing is false! */
			if ((!realtime || !valid_timing) && STREQ(prop_id, "end_frame"))
				return true;
			
			if (valid_timing && timing_mode == GP_STROKECONVERT_TIMING_CUSTOMGAP) {
				/* Only show for custom gaps! */
				if (STREQ(prop_id, "gap_duration"))
					return true;
				
				/* Only show randomness for non-null custom gaps! */
				if (STREQ(prop_id, "gap_randomness") && (gap_duration > 0.0f))
					return true;
				
				/* Only show seed for randomize action! */
				if (STREQ(prop_id, "seed") && (gap_duration > 0.0f) && (gap_randomness > 0.0f))
					return true;
			}
		}
	}
	
	/* Else, hidden! */
	return false;
}

static void gp_convert_ui(bContext *C, wmOperator *op)
{
	uiLayout *layout = op->layout;
	wmWindowManager *wm = CTX_wm_manager(C);
	PointerRNA ptr;
	
	RNA_pointer_create(&wm->id, op->type->srna, op->properties, &ptr);
	
	/* Main auto-draw call */
	uiDefAutoButsRNA(layout, &ptr, gp_convert_draw_check_prop, '\0');
}

void GPENCIL_OT_convert(wmOperatorType *ot)
{
	PropertyRNA *prop;
	
	/* identifiers */
	ot->name = "Convert Grease Pencil";
	ot->idname = "GPENCIL_OT_convert";
	ot->description = "Convert the active Grease Pencil layer to a new Curve Object";
	
	/* callbacks */
	ot->invoke = WM_menu_invoke;
	ot->exec = gp_convert_layer_exec;
	ot->poll = gp_convert_poll;
	ot->ui = gp_convert_ui;
	
	/* flags */
	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
	
	/* properties */
	ot->prop = RNA_def_enum(ot->srna, "type", prop_gpencil_convertmodes, 0, "Type", "Which type of curve to convert to");
	
	RNA_def_boolean(ot->srna, "use_normalize_weights", true, "Normalize Weight",
	                "Normalize weight (set from stroke width)");
	RNA_def_float(ot->srna, "radius_multiplier", 1.0f, 0.0f, 1000.0f, "Radius Fac",
	              "Multiplier for the points' radii (set from stroke width)", 0.0f, 10.0f);
	RNA_def_boolean(ot->srna, "use_link_strokes", true, "Link Strokes",
	                "Whether to link strokes with zero-radius sections of curves");
	
	prop = RNA_def_enum(ot->srna, "timing_mode", prop_gpencil_convert_timingmodes, GP_STROKECONVERT_TIMING_FULL,
	                    "Timing Mode", "How to use timing data stored in strokes");
	RNA_def_enum_funcs(prop, rna_GPConvert_mode_items);
	
	RNA_def_int(ot->srna, "frame_range", 100, 1, 10000, "Frame Range",
	            "The duration of evaluation of the path control curve", 1, 1000);
	RNA_def_int(ot->srna, "start_frame", 1, 1, 100000, "Start Frame",
	            "The start frame of the path control curve", 1, 100000);
	RNA_def_boolean(ot->srna, "use_realtime", false, "Realtime",
	                "Whether the path control curve reproduces the drawing in realtime, starting from Start Frame");
	prop = RNA_def_int(ot->srna, "end_frame", 250, 1, 100000, "End Frame",
	                   "The end frame of the path control curve (if Realtime is not set)", 1, 100000);
	RNA_def_property_update_runtime(prop, gp_convert_set_end_frame);
	
	RNA_def_float(ot->srna, "gap_duration", 0.0f, 0.0f, 10000.0f, "Gap Duration",
	              "Custom Gap mode: (Average) length of gaps, in frames "
	              "(Note: Realtime value, will be scaled if Realtime is not set)", 0.0f, 1000.0f);
	RNA_def_float(ot->srna, "gap_randomness", 0.0f, 0.0f, 10000.0f, "Gap Randomness",
	              "Custom Gap mode: Number of frames that gap lengths can vary", 0.0f, 1000.0f);
	RNA_def_int(ot->srna, "seed", 0, 0, 1000, "Random Seed",
	            "Custom Gap mode: Random generator seed", 0, 100);
	
	/* Note: Internal use, this one will always be hidden by UI code... */
	prop = RNA_def_boolean(ot->srna, "use_timing_data", false, "Has Valid Timing",
	                       "Whether the converted Grease Pencil layer has valid timing data (internal use)");
	RNA_def_property_flag(prop, PROP_SKIP_SAVE);
}

/* ************************************************ */
