/*
 * ***** 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) 2014, Blender Foundation
 *
 * Contributor(s): Joshua Leung, Antonio Vazquez
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/editors/gpencil/gpencil_utils.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_utildefines.h"
#include "BLT_translation.h"
#include "BLI_rand.h"

#include "DNA_meshdata_types.h"
#include "DNA_gpencil_types.h"
#include "DNA_brush_types.h"
#include "DNA_object_types.h"
#include "DNA_scene_types.h"
#include "DNA_screen_types.h"
#include "DNA_space_types.h"
#include "DNA_view3d_types.h"

#include "BKE_action.h"
#include "BKE_main.h"
#include "BKE_brush.h"
#include "BKE_context.h"
#include "BKE_gpencil.h"
#include "BKE_object.h"
#include "BKE_paint.h"
#include "BKE_material.h"
#include "BKE_tracking.h"

#include "WM_api.h"

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

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

#include "ED_gpencil.h"
#include "ED_clip.h"
#include "ED_view3d.h"
#include "ED_object.h"
#include "ED_screen.h"

#include "GPU_immediate.h"
#include "GPU_immediate_util.h"

#include "DEG_depsgraph.h"
#include "DEG_depsgraph_query.h"

#include "gpencil_intern.h"

/* ******************************************************** */
/* Context Wrangling... */

/* Get pointer to active Grease Pencil datablock, and an RNA-pointer to trace back to whatever owns it,
 * when context info is not available.
 */
bGPdata **ED_gpencil_data_get_pointers_direct(ID *screen_id, ScrArea *sa, Scene *scene, Object *ob, PointerRNA *r_ptr)
{
	/* if there's an active area, check if the particular editor may
	 * have defined any special Grease Pencil context for editing...
	 */
	if (sa) {
		SpaceLink *sl = sa->spacedata.first;

		switch (sa->spacetype) {
			/* XXX: Should we reduce reliance on context.gpencil_data for these cases? */
			case SPACE_BUTS: /* properties */
			case SPACE_INFO: /* header info (needed after workspaces merge) */
			{
				if (ob && (ob->type == OB_GPENCIL)) {
					/* GP Object */
					if (r_ptr) RNA_id_pointer_create(&ob->id, r_ptr);
					return (bGPdata **)&ob->data;
				}
				else {
					return NULL;
				}

				break;
			}

			case SPACE_TOPBAR: /* Topbar (needed after topbar merge) */
			case SPACE_VIEW3D: /* 3D-View */
			{
				if (ob && (ob->type == OB_GPENCIL)) {
					/* GP Object */
					if (r_ptr) RNA_id_pointer_create(&ob->id, r_ptr);
					return (bGPdata **)&ob->data;
				}
				else {
					/* Annotations */
					/* XXX: */
					if (r_ptr) RNA_id_pointer_create(&scene->id, r_ptr);
					return &scene->gpd;
				}

				break;
			}
			case SPACE_NODE: /* Nodes Editor */
			{
				SpaceNode *snode = (SpaceNode *)sl;

				/* return the GP data for the active node block/node */
				if (snode && snode->nodetree) {
					/* for now, as long as there's an active node tree, default to using that in the Nodes Editor */
					if (r_ptr) RNA_id_pointer_create(&snode->nodetree->id, r_ptr);
					return &snode->nodetree->gpd;
				}

				/* even when there is no node-tree, don't allow this to flow to scene */
				return NULL;
			}
			case SPACE_SEQ: /* Sequencer */
			{
				SpaceSeq *sseq = (SpaceSeq *)sl;

				/* for now, Grease Pencil data is associated with the space (actually preview region only) */
				/* XXX our convention for everything else is to link to data though... */
				if (r_ptr) RNA_pointer_create(screen_id, &RNA_SpaceSequenceEditor, sseq, r_ptr);
				return &sseq->gpd;
			}
			case SPACE_IMAGE: /* Image/UV Editor */
			{
				SpaceImage *sima = (SpaceImage *)sl;

				/* for now, Grease Pencil data is associated with the space... */
				/* XXX our convention for everything else is to link to data though... */
				if (r_ptr) RNA_pointer_create(screen_id, &RNA_SpaceImageEditor, sima, r_ptr);
				return &sima->gpd;
			}
			case SPACE_CLIP: /* Nodes Editor */
			{
				SpaceClip *sc = (SpaceClip *)sl;
				MovieClip *clip = ED_space_clip_get_clip(sc);

				if (clip) {
					if (sc->gpencil_src == SC_GPENCIL_SRC_TRACK) {
						MovieTrackingTrack *track = BKE_tracking_track_get_active(&clip->tracking);

						if (!track)
							return NULL;

						if (r_ptr) RNA_pointer_create(&clip->id, &RNA_MovieTrackingTrack, track, r_ptr);
						return &track->gpd;
					}
					else {
						if (r_ptr) RNA_id_pointer_create(&clip->id, r_ptr);
						return &clip->gpd;
					}
				}
				break;
			}
			default: /* unsupported space */
				return NULL;
		}
	}

	return NULL;
}

/* Get pointer to active Grease Pencil datablock, and an RNA-pointer to trace back to whatever owns it */
bGPdata **ED_gpencil_data_get_pointers(const bContext *C, PointerRNA *r_ptr)
{
	ID *screen_id = (ID *)CTX_wm_screen(C);
	Scene *scene = CTX_data_scene(C);
	ScrArea *sa = CTX_wm_area(C);
	Object *ob = CTX_data_active_object(C);

	return ED_gpencil_data_get_pointers_direct(screen_id, sa, scene, ob, r_ptr);
}

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

/* Get the active Grease Pencil datablock, when context is not available */
bGPdata *ED_gpencil_data_get_active_direct(ID *screen_id, ScrArea *sa, Scene *scene, Object *ob)
{
	bGPdata **gpd_ptr = ED_gpencil_data_get_pointers_direct(screen_id, sa, scene, ob, NULL);
	return (gpd_ptr) ? *(gpd_ptr) : NULL;
}

/**
 * Get the active Grease Pencil datablock
 * \note This is the original (bmain) copy of the datablock, stored in files.
 *       Do not use for reading evaluated copies of GP Objects data
 */
bGPdata *ED_gpencil_data_get_active(const bContext *C)
{
	bGPdata **gpd_ptr = ED_gpencil_data_get_pointers(C, NULL);
	return (gpd_ptr) ? *(gpd_ptr) : NULL;
}

/**
 * Get the evaluated copy of the active Grease Pencil datablock (where applicable)
 * - For the 3D View (i.e. "GP Objects"), this gives the evaluated copy of the GP datablock
 *   (i.e. a copy of the active GP datablock for the active object, where modifiers have been
 *   applied). This is needed to correctly work with "Copy-on-Write"
 * - For all other editors (i.e. "GP Annotations"), this just gives the active datablock
 *   like for ED_gpencil_data_get_active()
 */
bGPdata *ED_gpencil_data_get_active_evaluated(const bContext *C)
{
	ID *screen_id = (ID *)CTX_wm_screen(C);
	ScrArea *sa = CTX_wm_area(C);

	const Depsgraph *depsgraph = CTX_data_depsgraph(C);
	Scene *scene_eval = DEG_get_evaluated_scene(depsgraph);
	Object *ob = CTX_data_active_object(C);
	Object *ob_eval = DEG_get_evaluated_object(depsgraph, ob);

	/* if (ob && ob->type == OB_GPENCIL) BLI_assert(ob_eval->data == DEG_get_evaluated_id(ob->data)); */
	return ED_gpencil_data_get_active_direct(screen_id, sa, scene_eval, ob_eval);
}

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

/**
 * Utility to check whether the r_ptr output of ED_gpencil_data_get_pointers()
 * is for annotation usage.
 */
bool ED_gpencil_data_owner_is_annotation(PointerRNA *owner_ptr)
{
	/* Key Assumption: If the pointer is an object, we're dealing with a GP Object's data.
	 * Otherwise, the GP datablock is being used for annotations (i.e. everywhere else)
	 */
	return ((owner_ptr) && (owner_ptr->type != &RNA_Object));
}

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

// XXX: this should be removed... We really shouldn't duplicate logic like this!
bGPdata *ED_gpencil_data_get_active_v3d(ViewLayer *view_layer)
{
	Base *base = view_layer->basact;
	bGPdata *gpd = NULL;

	/* We have to make sure active object is actually visible and selected, else we must use default scene gpd,
	 * to be consistent with ED_gpencil_data_get_active's behavior.
	 */
	if (base && TESTBASE(base)) {
		if (base->object->type == OB_GPENCIL)
			gpd = base->object->data;
	}
	return gpd ? gpd : NULL;
}

/* ******************************************************** */
/* Keyframe Indicator Checks */

/* Check whether there's an active GP keyframe on the current frame */
bool ED_gpencil_has_keyframe_v3d(Scene *UNUSED(scene), Object *ob, int cfra)
{
	if (ob && ob->data && (ob->type == OB_GPENCIL)) {
		bGPDlayer *gpl = BKE_gpencil_layer_getactive(ob->data);
		if (gpl) {
			if (gpl->actframe) {
				// XXX: assumes that frame has been fetched already
				return (gpl->actframe->framenum == cfra);
			}
			else {
				/* XXX: disabled as could be too much of a penalty */
				/* return BKE_gpencil_layer_find_frame(gpl, cfra); */
			}
		}
	}

	return false;
}

/* ******************************************************** */
/* Poll Callbacks */

/* poll callback for adding data/layers - special */
bool gp_add_poll(bContext *C)
{
	/* the base line we have is that we have somewhere to add Grease Pencil data */
	return ED_gpencil_data_get_pointers(C, NULL) != NULL;
}

/* poll callback for checking if there is an active layer */
bool gp_active_layer_poll(bContext *C)
{
	bGPdata *gpd = ED_gpencil_data_get_active(C);
	bGPDlayer *gpl = BKE_gpencil_layer_getactive(gpd);

	return (gpl != NULL);
}

/* poll callback for checking if there is an active brush */
bool gp_active_brush_poll(bContext *C)
{
	ToolSettings *ts = CTX_data_tool_settings(C);
	Paint *paint = &ts->gp_paint->paint;
	if (paint) {
		return (paint->brush != NULL);
	}
	else {
		return false;
	}
}

/* ******************************************************** */
/* Dynamic Enums of GP Layers */
/* NOTE: These include an option to create a new layer and use that... */

/* Just existing layers */
const EnumPropertyItem *ED_gpencil_layers_enum_itemf(
        bContext *C, PointerRNA *UNUSED(ptr), PropertyRNA *UNUSED(prop), bool *r_free)
{
	bGPdata *gpd = CTX_data_gpencil_data(C);
	bGPDlayer *gpl;
	EnumPropertyItem *item = NULL, item_tmp = {0};
	int totitem = 0;
	int i = 0;

	if (ELEM(NULL, C, gpd)) {
		return DummyRNA_DEFAULT_items;
	}

	/* Existing layers */
	for (gpl = gpd->layers.first; gpl; gpl = gpl->next, i++) {
		item_tmp.identifier = gpl->info;
		item_tmp.name = gpl->info;
		item_tmp.value = i;

		if (gpl->flag & GP_LAYER_ACTIVE)
			item_tmp.icon = ICON_GREASEPENCIL;
		else
			item_tmp.icon = ICON_NONE;

		RNA_enum_item_add(&item, &totitem, &item_tmp);
	}

	RNA_enum_item_end(&item, &totitem);
	*r_free = true;

	return item;
}

/* Existing + Option to add/use new layer */
const EnumPropertyItem *ED_gpencil_layers_with_new_enum_itemf(
        bContext *C, PointerRNA *UNUSED(ptr), PropertyRNA *UNUSED(prop), bool *r_free)
{
	bGPdata *gpd = CTX_data_gpencil_data(C);
	bGPDlayer *gpl;
	EnumPropertyItem *item = NULL, item_tmp = {0};
	int totitem = 0;
	int i = 0;

	if (ELEM(NULL, C, gpd)) {
		return DummyRNA_DEFAULT_items;
	}

	/* Create new layer */
	/* TODO: have some way of specifying that we don't want this? */
	{
		/* "New Layer" entry */
		item_tmp.identifier = "__CREATE__";
		item_tmp.name = "New Layer";
		item_tmp.value = -1;
		item_tmp.icon = ICON_ZOOMIN;
		RNA_enum_item_add(&item, &totitem, &item_tmp);

		/* separator */
		RNA_enum_item_add_separator(&item, &totitem);
	}

	/* Existing layers */
	for (gpl = gpd->layers.first, i = 0; gpl; gpl = gpl->next, i++) {
		item_tmp.identifier = gpl->info;
		item_tmp.name = gpl->info;
		item_tmp.value = i;

		if (gpl->flag & GP_LAYER_ACTIVE)
			item_tmp.icon = ICON_GREASEPENCIL;
		else
			item_tmp.icon = ICON_NONE;

		RNA_enum_item_add(&item, &totitem, &item_tmp);
	}

	RNA_enum_item_end(&item, &totitem);
	*r_free = true;

	return item;
}


/* ******************************************************** */
/* Brush Tool Core */

/**
 * Check whether a given stroke segment is inside a circular brush
 *
 * \param mval     The current screen-space coordinates (midpoint) of the brush
 * \param mvalo    The previous screen-space coordinates (midpoint) of the brush (NOT CURRENTLY USED)
 * \param rad      The radius of the brush
 *
 * \param x0, y0   The screen-space x and y coordinates of the start of the stroke segment
 * \param x1, y1   The screen-space x and y coordinates of the end of the stroke segment
 */
bool gp_stroke_inside_circle(const int mval[2], const int UNUSED(mvalo[2]),
                             int rad, int x0, int y0, int x1, int y1)
{
	/* simple within-radius check for now */
	const float mval_fl[2]     = {mval[0], mval[1]};
	const float screen_co_a[2] = {x0, y0};
	const float screen_co_b[2] = {x1, y1};

	if (edge_inside_circle(mval_fl, rad, screen_co_a, screen_co_b)) {
		return true;
	}

	/* not inside */
	return false;
}

/* ******************************************************** */
/* Stroke Validity Testing */

/* Check whether given stroke can be edited given the supplied context */
/* TODO: do we need additional flags for screenspace vs dataspace? */
bool ED_gpencil_stroke_can_use_direct(const ScrArea *sa, const bGPDstroke *gps)
{
	/* sanity check */
	if (ELEM(NULL, sa, gps))
		return false;

	/* filter stroke types by flags + spacetype */
	if (gps->flag & GP_STROKE_3DSPACE) {
		/* 3D strokes - only in 3D view */
		return ((sa->spacetype == SPACE_VIEW3D) || (sa->spacetype == SPACE_BUTS));
	}
	else if (gps->flag & GP_STROKE_2DIMAGE) {
		/* Special "image" strokes - only in Image Editor */
		return (sa->spacetype == SPACE_IMAGE);
	}
	else if (gps->flag & GP_STROKE_2DSPACE) {
		/* 2D strokes (dataspace) - for any 2D view (i.e. everything other than 3D view) */
		return (sa->spacetype != SPACE_VIEW3D);
	}
	else {
		/* view aligned - anything goes */
		return true;
	}
}

/* Check whether given stroke can be edited in the current context */
bool ED_gpencil_stroke_can_use(const bContext *C, const bGPDstroke *gps)
{
	ScrArea *sa = CTX_wm_area(C);
	return ED_gpencil_stroke_can_use_direct(sa, gps);
}

/* Check whether given stroke can be edited for the current color */
bool ED_gpencil_stroke_color_use(Object *ob, const bGPDlayer *gpl, const bGPDstroke *gps)
{
	/* check if the color is editable */
	MaterialGPencilStyle *gp_style = BKE_material_gpencil_settings_get(ob, gps->mat_nr + 1);

	if (gp_style != NULL) {
		if (gp_style->flag & GP_STYLE_COLOR_HIDE)
			return false;
		if (((gpl->flag & GP_LAYER_UNLOCK_COLOR) == 0) && (gp_style->flag & GP_STYLE_COLOR_LOCKED))
			return false;
	}

	return true;
}

/* ******************************************************** */
/* Space Conversion */

/**
 * Init settings for stroke point space conversions
 *
 * \param r_gsc: [out] The space conversion settings struct, populated with necessary params
 */
void gp_point_conversion_init(bContext *C, GP_SpaceConversion *r_gsc)
{
	ScrArea *sa = CTX_wm_area(C);
	ARegion *ar = CTX_wm_region(C);

	/* zero out the storage (just in case) */
	memset(r_gsc, 0, sizeof(GP_SpaceConversion));
	unit_m4(r_gsc->mat);

	/* store settings */
	r_gsc->sa = sa;
	r_gsc->ar = ar;
	r_gsc->v2d = &ar->v2d;

	/* init region-specific stuff */
	if (sa->spacetype == SPACE_VIEW3D) {
		wmWindow *win = CTX_wm_window(C);
		Scene *scene = CTX_data_scene(C);
		struct Depsgraph *depsgraph = CTX_data_depsgraph(C);
		View3D *v3d = (View3D *)CTX_wm_space_data(C);
		RegionView3D *rv3d = ar->regiondata;

		/* init 3d depth buffers */
		view3d_operator_needs_opengl(C);

		view3d_region_operator_needs_opengl(win, ar);
		ED_view3d_autodist_init(depsgraph, ar, v3d, 0);

		/* for camera view set the subrect */
		if (rv3d->persp == RV3D_CAMOB) {
			ED_view3d_calc_camera_border(scene, CTX_data_depsgraph(C), ar, v3d, rv3d, &r_gsc->subrect_data, true); /* no shift */
			r_gsc->subrect = &r_gsc->subrect_data;
		}
	}
}

/**
 * Convert point to parent space
 *
 * \param pt         Original point
 * \param diff_mat   Matrix with the difference between original parent matrix
 * \param[out] r_pt  Pointer to new point after apply matrix
 */
void gp_point_to_parent_space(bGPDspoint *pt, float diff_mat[4][4], bGPDspoint *r_pt)
{
	float fpt[3];

	mul_v3_m4v3(fpt, diff_mat, &pt->x);
	copy_v3_v3(&r_pt->x, fpt);
}

/**
 * Change position relative to parent object
 */
void gp_apply_parent(Depsgraph *depsgraph, Object *obact, bGPdata *gpd, bGPDlayer *gpl, bGPDstroke *gps)
{
	bGPDspoint *pt;
	int i;

	/* undo matrix */
	float diff_mat[4][4];
	float inverse_diff_mat[4][4];
	float fpt[3];

	ED_gpencil_parent_location(depsgraph, obact, gpd, gpl, diff_mat);
	invert_m4_m4(inverse_diff_mat, diff_mat);

	for (i = 0; i < gps->totpoints; i++) {
		pt = &gps->points[i];
		mul_v3_m4v3(fpt, inverse_diff_mat, &pt->x);
		copy_v3_v3(&pt->x, fpt);
	}
}

/**
 * Change point position relative to parent object
 */
void gp_apply_parent_point(Depsgraph *depsgraph, Object *obact, bGPdata *gpd, bGPDlayer *gpl, bGPDspoint *pt)
{
	/* undo matrix */
	float diff_mat[4][4];
	float inverse_diff_mat[4][4];
	float fpt[3];

	ED_gpencil_parent_location(depsgraph, obact, gpd, gpl, diff_mat);
	invert_m4_m4(inverse_diff_mat, diff_mat);

	mul_v3_m4v3(fpt, inverse_diff_mat, &pt->x);
	copy_v3_v3(&pt->x, fpt);
}

/**
 * Convert a Grease Pencil coordinate (i.e. can be 2D or 3D) to screenspace (2D)
 *
 * \param[out] r_x  The screen-space x-coordinate of the point
 * \param[out] r_y  The screen-space y-coordinate of the point
 *
 * \warning This assumes that the caller has already checked whether the stroke in question can be drawn.
 */
void gp_point_to_xy(GP_SpaceConversion *gsc, bGPDstroke *gps, bGPDspoint *pt,
                    int *r_x, int *r_y)
{
	ARegion *ar = gsc->ar;
	View2D *v2d = gsc->v2d;
	rctf *subrect = gsc->subrect;
	int xyval[2];

	/* sanity checks */
	BLI_assert(!(gps->flag & GP_STROKE_3DSPACE) || (gsc->sa->spacetype == SPACE_VIEW3D));
	BLI_assert(!(gps->flag & GP_STROKE_2DSPACE) || (gsc->sa->spacetype != SPACE_VIEW3D));


	if (gps->flag & GP_STROKE_3DSPACE) {
		if (ED_view3d_project_int_global(ar, &pt->x, xyval, V3D_PROJ_TEST_NOP) == V3D_PROJ_RET_OK) {
			*r_x = xyval[0];
			*r_y = xyval[1];
		}
		else {
			*r_x = V2D_IS_CLIPPED;
			*r_y = V2D_IS_CLIPPED;
		}
	}
	else if (gps->flag & GP_STROKE_2DSPACE) {
		float vec[3] = {pt->x, pt->y, 0.0f};
		mul_m4_v3(gsc->mat, vec);
		UI_view2d_view_to_region_clip(v2d, vec[0], vec[1], r_x, r_y);
	}
	else {
		if (subrect == NULL) {
			/* normal 3D view (or view space) */
			*r_x = (int)(pt->x / 100 * ar->winx);
			*r_y = (int)(pt->y / 100 * ar->winy);
		}
		else {
			/* camera view, use subrect */
			*r_x = (int)((pt->x / 100) * BLI_rctf_size_x(subrect)) + subrect->xmin;
			*r_y = (int)((pt->y / 100) * BLI_rctf_size_y(subrect)) + subrect->ymin;
		}
	}
}

/**
 * Convert a Grease Pencil coordinate (i.e. can be 2D or 3D) to screenspace (2D)
 *
 * Just like gp_point_to_xy(), except the resulting coordinates are floats not ints.
 * Use this version to solve "stair-step" artifacts which may arise when roundtripping the calculations.
 *
 * \param r_x: [out] The screen-space x-coordinate of the point
 * \param r_y: [out] The screen-space y-coordinate of the point
 *
 * \warning This assumes that the caller has already checked whether the stroke in question can be drawn
 */
void gp_point_to_xy_fl(GP_SpaceConversion *gsc, bGPDstroke *gps, bGPDspoint *pt,
                       float *r_x, float *r_y)
{
	ARegion *ar = gsc->ar;
	View2D *v2d = gsc->v2d;
	rctf *subrect = gsc->subrect;
	float xyval[2];

	/* sanity checks */
	BLI_assert(!(gps->flag & GP_STROKE_3DSPACE) || (gsc->sa->spacetype == SPACE_VIEW3D));
	BLI_assert(!(gps->flag & GP_STROKE_2DSPACE) || (gsc->sa->spacetype != SPACE_VIEW3D));


	if (gps->flag & GP_STROKE_3DSPACE) {
		if (ED_view3d_project_float_global(ar, &pt->x, xyval, V3D_PROJ_TEST_NOP) == V3D_PROJ_RET_OK) {
			*r_x = xyval[0];
			*r_y = xyval[1];
		}
		else {
			*r_x = 0.0f;
			*r_y = 0.0f;
		}
	}
	else if (gps->flag & GP_STROKE_2DSPACE) {
		float vec[3] = {pt->x, pt->y, 0.0f};
		int t_x, t_y;

		mul_m4_v3(gsc->mat, vec);
		UI_view2d_view_to_region_clip(v2d, vec[0], vec[1], &t_x, &t_y);

		if ((t_x == t_y) && (t_x == V2D_IS_CLIPPED)) {
			/* XXX: Or should we just always use the values as-is? */
			*r_x = 0.0f;
			*r_y = 0.0f;
		}
		else {
			*r_x = (float)t_x;
			*r_y = (float)t_y;
		}
	}
	else {
		if (subrect == NULL) {
			/* normal 3D view (or view space) */
			*r_x = (pt->x / 100.0f * ar->winx);
			*r_y = (pt->y / 100.0f * ar->winy);
		}
		else {
			/* camera view, use subrect */
			*r_x = ((pt->x / 100.0f) * BLI_rctf_size_x(subrect)) + subrect->xmin;
			*r_y = ((pt->y / 100.0f) * BLI_rctf_size_y(subrect)) + subrect->ymin;
		}
	}
}

/**
 * Project screenspace coordinates to 3D-space
 *
 * For use with editing tools where it is easier to perform the operations in 2D,
 * and then later convert the transformed points back to 3D.
 *
 * \param screen_co: The screenspace 2D coordinates to convert to
 * \param r_out: The resulting 3D coordinates of the input point
 *
 * \note We include this as a utility function, since the standard method
 * involves quite a few steps, which are invariably always the same
 * for all GPencil operations. So, it's nicer to just centralize these.
 *
 * \warning Assumes that it is getting called in a 3D view only.
 */
bool gp_point_xy_to_3d(GP_SpaceConversion *gsc, Scene *scene, const float screen_co[2], float r_out[3])
{
	View3D *v3d = gsc->sa->spacedata.first;
	RegionView3D *rv3d = gsc->ar->regiondata;
	float *rvec = ED_view3d_cursor3d_get(scene, v3d)->location;
	float ref[3] = {rvec[0], rvec[1], rvec[2]};
	float zfac = ED_view3d_calc_zfac(rv3d, rvec, NULL);

	float mval_f[2], mval_prj[2];
	float dvec[3];

	copy_v2_v2(mval_f, screen_co);

	if (ED_view3d_project_float_global(gsc->ar, ref, mval_prj, V3D_PROJ_TEST_NOP) == V3D_PROJ_RET_OK) {
		sub_v2_v2v2(mval_f, mval_prj, mval_f);
		ED_view3d_win_to_delta(gsc->ar, mval_f, dvec, zfac);
		sub_v3_v3v3(r_out, rvec, dvec);

		return true;
	}
	else {
		zero_v3(r_out);

		return false;
	}
}

/**
 * Convert tGPspoint (temporary 2D/screenspace point data used by GP modal operators)
 * to 3D coordinates.
 *
 * \param point2D: The screenspace 2D point data to convert
 * \param depth: Depth array (via ED_view3d_autodist_depth())
 * \param[out] r_out: The resulting 2D point data
 */
void gp_stroke_convertcoords_tpoint(
        Scene *scene, ARegion *ar, View3D *v3d,
        Object *ob, bGPDlayer *gpl,
        const tGPspoint *point2D, float *depth,
        float r_out[3])
{
	ToolSettings *ts = scene->toolsettings;
	const int mval[2] = {point2D->x, point2D->y};

	if ((depth != NULL) && (ED_view3d_autodist_simple(ar, mval, r_out, 0, depth))) {
		/* projecting onto 3D-Geometry
		*	- nothing more needs to be done here, since view_autodist_simple() has already done it
		*/
	}
	else {
		float mval_f[2] = {(float)point2D->x, (float)point2D->y};
		float mval_prj[2];
		float rvec[3], dvec[3];
		float zfac;

		/* Current method just converts each point in screen-coordinates to
		 * 3D-coordinates using the 3D-cursor as reference.
		 */
		ED_gp_get_drawing_reference(v3d, scene, ob, gpl, ts->gpencil_v3d_align, rvec);
		zfac = ED_view3d_calc_zfac(ar->regiondata, rvec, NULL);

		if (ED_view3d_project_float_global(ar, rvec, mval_prj, V3D_PROJ_TEST_NOP) == V3D_PROJ_RET_OK) {
			sub_v2_v2v2(mval_f, mval_prj, mval_f);
			ED_view3d_win_to_delta(ar, mval_f, dvec, zfac);
			sub_v3_v3v3(r_out, rvec, dvec);
		}
		else {
			zero_v3(r_out);
		}
	}
}

/**
 * Get drawing reference point for conversion or projection of the stroke
 * \param[out] r_vec : Reference point found
 */
void ED_gp_get_drawing_reference(
        View3D *v3d, Scene *scene, Object *ob, bGPDlayer *UNUSED(gpl),
        char align_flag, float r_vec[3])
{
	const float *fp = ED_view3d_cursor3d_get(scene, v3d)->location;

	/* if using a gpencil object at cursor mode, can use the location of the object */
	if (align_flag & GP_PROJECT_VIEWSPACE) {
		if (ob && (ob->type == OB_GPENCIL)) {
			/* fallback (no strokes) - use cursor or object location */
			if (align_flag & GP_PROJECT_CURSOR) {
				/* use 3D-cursor */
				copy_v3_v3(r_vec, fp);
			}
			else {
				/* use object location */
				copy_v3_v3(r_vec, ob->obmat[3]);
			}
		}
	}
	else {
		/* use 3D-cursor */
		copy_v3_v3(r_vec, fp);
	}
}


/**
 * Reproject all points of the stroke to a plane locked to axis to avoid stroke offset
 */
void ED_gp_project_stroke_to_plane(Object *ob, RegionView3D *rv3d, bGPDstroke *gps, const float origin[3], const int axis)
{
	float plane_normal[3];
	float vn[3];

	float ray[3];
	float rpoint[3];

	/* normal vector for a plane locked to axis */
	zero_v3(plane_normal);
	if (axis < 0) {
		/* if the axis is not locked, need a vector to the view direction
		* in order to get the right size of the stroke.
		*/
		ED_view3d_global_to_vector(rv3d, origin, plane_normal);
	}
	else {
		plane_normal[axis] = 1.0f;
		/* if object, apply object rotation */
		if (ob && (ob->type == OB_GPENCIL)) {
			mul_mat3_m4_v3(ob->obmat, plane_normal);
		}
	}

	/* Reproject the points in the plane */
	for (int i = 0; i < gps->totpoints; i++) {
		bGPDspoint *pt = &gps->points[i];

		/* get a vector from the point with the current view direction of the viewport */
		ED_view3d_global_to_vector(rv3d, &pt->x, vn);

		/* calculate line extreme point to create a ray that cross the plane */
		mul_v3_fl(vn, -50.0f);
		add_v3_v3v3(ray, &pt->x, vn);

		/* if the line never intersect, the point is not changed */
		if (isect_line_plane_v3(rpoint, &pt->x, ray, origin, plane_normal)) {
			copy_v3_v3(&pt->x, rpoint);
		}
	}
}

/**
 * Reproject given point to a plane locked to axis to avoid stroke offset
 * \param[in, out] pt : Point to affect
 */
void ED_gp_project_point_to_plane(Object *ob, RegionView3D *rv3d, const float origin[3], const int axis, bGPDspoint *pt)
{
	float plane_normal[3];
	float vn[3];

	float ray[3];
	float rpoint[3];

	/* normal vector for a plane locked to axis */
	zero_v3(plane_normal);
	if (axis < 0) {
		/* if the axis is not locked, need a vector to the view direction
		 * in order to get the right size of the stroke.
		 */
		ED_view3d_global_to_vector(rv3d, origin, plane_normal);
	}
	else {
		plane_normal[axis] = 1.0f;
		/* if object, apply object rotation */
		if (ob && (ob->type == OB_GPENCIL)) {
			mul_mat3_m4_v3(ob->obmat, plane_normal);
		}
	}


	/* Reproject the points in the plane */
	/* get a vector from the point with the current view direction of the viewport */
	ED_view3d_global_to_vector(rv3d, &pt->x, vn);

	/* calculate line extrem point to create a ray that cross the plane */
	mul_v3_fl(vn, -50.0f);
	add_v3_v3v3(ray, &pt->x, vn);

	/* if the line never intersect, the point is not changed */
	if (isect_line_plane_v3(rpoint, &pt->x, ray, origin, plane_normal)) {
		copy_v3_v3(&pt->x, rpoint);
	}
}

/* ******************************************************** */
/* Stroke Operations */
// XXX: Check if these functions duplicate stuff in blenkernel, and/or whether we should just deduplicate

/**
 * Subdivide a stroke once, by adding a point half way between each pair of existing points
 * \param gps           Stroke data
 * \param subdivide      Number of times to subdivide
 */
void gp_subdivide_stroke(bGPDstroke *gps, const int subdivide)
{
	bGPDspoint *temp_points;
	int totnewpoints, oldtotpoints;
	int i2;

	/* loop as many times as levels */
	for (int s = 0; s < subdivide; s++) {
		totnewpoints = gps->totpoints - 1;
		/* duplicate points in a temp area */
		temp_points = MEM_dupallocN(gps->points);
		oldtotpoints = gps->totpoints;

		/* resize the points arrys */
		gps->totpoints += totnewpoints;
		gps->points = MEM_recallocN(gps->points, sizeof(*gps->points) * gps->totpoints);
		gps->dvert = MEM_recallocN(gps->dvert, sizeof(*gps->dvert) * gps->totpoints);
		gps->flag |= GP_STROKE_RECALC_CACHES;

		/* move points from last to first to new place */
		i2 = gps->totpoints - 1;
		for (int i = oldtotpoints - 1; i > 0; i--) {
			bGPDspoint *pt = &temp_points[i];
			bGPDspoint *pt_final = &gps->points[i2];
			MDeformVert *dvert = &gps->dvert[i];
			MDeformVert *dvert_final = &gps->dvert[i2];

			copy_v3_v3(&pt_final->x, &pt->x);
			pt_final->pressure = pt->pressure;
			pt_final->strength = pt->strength;
			pt_final->time = pt->time;
			pt_final->flag = pt->flag;
			pt_final->uv_fac = pt->uv_fac;
			pt_final->uv_rot = pt->uv_rot;

			dvert_final->totweight = dvert->totweight;
			dvert_final->dw = dvert->dw;

			i2 -= 2;
		}
		/* interpolate mid points */
		i2 = 1;
		for (int i = 0; i < oldtotpoints - 1; i++) {
			bGPDspoint *pt = &temp_points[i];
			bGPDspoint *next = &temp_points[i + 1];
			bGPDspoint *pt_final = &gps->points[i2];
			MDeformVert *dvert_final = &gps->dvert[i2];

			/* add a half way point */
			interp_v3_v3v3(&pt_final->x, &pt->x, &next->x, 0.5f);
			pt_final->pressure = interpf(pt->pressure, next->pressure, 0.5f);
			pt_final->strength = interpf(pt->strength, next->strength, 0.5f);
			CLAMP(pt_final->strength, GPENCIL_STRENGTH_MIN, 1.0f);
			pt_final->time = interpf(pt->time, next->time, 0.5f);
			pt_final->uv_fac = interpf(pt->uv_fac, next->uv_fac, 0.5f);
			pt_final->uv_rot = interpf(pt->uv_rot, next->uv_rot, 0.5f);

			dvert_final->totweight = 0;
			dvert_final->dw = NULL;

			i2 += 2;
		}

		MEM_SAFE_FREE(temp_points);

		/* move points to smooth stroke */
		/* duplicate points in a temp area with the new subdivide data */
		temp_points = MEM_dupallocN(gps->points);

		/* extreme points are not changed */
		for (int i = 0; i < gps->totpoints - 2; i++) {
			bGPDspoint *pt = &temp_points[i];
			bGPDspoint *next = &temp_points[i + 1];
			bGPDspoint *pt_final = &gps->points[i + 1];

			/* move point */
			interp_v3_v3v3(&pt_final->x, &pt->x, &next->x, 0.5f);
		}
		/* free temp memory */
		MEM_SAFE_FREE(temp_points);
	}
}

/**
 * Add randomness to stroke
 * \param gps           Stroke data
 * \param brush         Brush data
 */
void gp_randomize_stroke(bGPDstroke *gps, Brush *brush, RNG *rng)
{
	bGPDspoint *pt1, *pt2, *pt3;
	float v1[3];
	float v2[3];
	if (gps->totpoints < 3) {
		return;
	}

	/* get two vectors using 3 points */
	pt1 = &gps->points[0];
	pt2 = &gps->points[1];
	pt3 = &gps->points[(int)(gps->totpoints * 0.75)];

	sub_v3_v3v3(v1, &pt2->x, &pt1->x);
	sub_v3_v3v3(v2, &pt3->x, &pt2->x);
	normalize_v3(v1);
	normalize_v3(v2);

	/* get normal vector to plane created by two vectors */
	float normal[3];
	cross_v3_v3v3(normal, v1, v2);
	normalize_v3(normal);

	/* get orthogonal vector to plane to rotate random effect */
	float ortho[3];
	cross_v3_v3v3(ortho, v1, normal);
	normalize_v3(ortho);

	/* Read all points and apply shift vector (first and last point not modified) */
	for (int i = 1; i < gps->totpoints - 1; i++) {
		bGPDspoint *pt = &gps->points[i];
		/* get vector with shift (apply a division because random is too sensitive */
		const float fac = BLI_rng_get_float(rng) * (brush->gpencil_settings->draw_random_sub / 10.0f);
		float svec[3];
		copy_v3_v3(svec, ortho);
		if (BLI_rng_get_float(rng) > 0.5f) {
			mul_v3_fl(svec, -fac);
		}
		else {
			mul_v3_fl(svec, fac);
		}

		/* apply shift */
		add_v3_v3(&pt->x, svec);
	}
}

/* ******************************************************** */
/* Layer Parenting  - Compute Parent Transforms */

/* calculate difference matrix */
void ED_gpencil_parent_location(
        const Depsgraph *depsgraph, Object *obact, bGPdata *UNUSED(gpd),
        bGPDlayer *gpl, float diff_mat[4][4])
{
	Object *ob_eval = depsgraph != NULL ? DEG_get_evaluated_object(depsgraph, obact) : obact;
	Object *obparent = gpl->parent;
	Object *obparent_eval = depsgraph != NULL ? DEG_get_evaluated_object(depsgraph, obparent) : obparent;

	/* if not layer parented, try with object parented */
	if (obparent_eval == NULL) {
		if (ob_eval != NULL) {
			if (ob_eval->type == OB_GPENCIL) {
				copy_m4_m4(diff_mat, ob_eval->obmat);
				return;
			}
		}
		/* not gpencil object */
		unit_m4(diff_mat);
		return;
	}
	else {
		if ((gpl->partype == PAROBJECT) || (gpl->partype == PARSKEL)) {
			mul_m4_m4m4(diff_mat, obparent_eval->obmat, gpl->inverse);
			return;
		}
		else if (gpl->partype == PARBONE) {
			bPoseChannel *pchan = BKE_pose_channel_find_name(obparent_eval->pose, gpl->parsubstr);
			if (pchan) {
				float tmp_mat[4][4];
				mul_m4_m4m4(tmp_mat, obparent_eval->obmat, pchan->pose_mat);
				mul_m4_m4m4(diff_mat, tmp_mat, gpl->inverse);
			}
			else {
				mul_m4_m4m4(diff_mat, obparent_eval->obmat, gpl->inverse); /* if bone not found use object (armature) */
			}
			return;
		}
		else {
			unit_m4(diff_mat); /* not defined type */
		}
	}
}

/* reset parent matrix for all layers */
void ED_gpencil_reset_layers_parent(Depsgraph *depsgraph, Object *obact, bGPdata *gpd)
{
	bGPDspoint *pt;
	int i;
	float diff_mat[4][4];
	float cur_mat[4][4];

	for (bGPDlayer *gpl = gpd->layers.first; gpl; gpl = gpl->next) {
		if (gpl->parent != NULL) {
			/* calculate new matrix */
			if ((gpl->partype == PAROBJECT) || (gpl->partype == PARSKEL)) {
				invert_m4_m4(cur_mat, gpl->parent->obmat);
			}
			else if (gpl->partype == PARBONE) {
				bPoseChannel *pchan = BKE_pose_channel_find_name(gpl->parent->pose, gpl->parsubstr);
				if (pchan) {
					float tmp_mat[4][4];
					mul_m4_m4m4(tmp_mat, gpl->parent->obmat, pchan->pose_mat);
					invert_m4_m4(cur_mat, tmp_mat);
				}
			}

			/* only redo if any change */
			if (!equals_m4m4(gpl->inverse, cur_mat)) {
				/* first apply current transformation to all strokes */
				ED_gpencil_parent_location(depsgraph, obact, gpd, gpl, diff_mat);
				for (bGPDframe *gpf = gpl->frames.first; gpf; gpf = gpf->next) {
					for (bGPDstroke *gps = gpf->strokes.first; gps; gps = gps->next) {
						for (i = 0, pt = gps->points; i < gps->totpoints; i++, pt++) {
							mul_m4_v3(diff_mat, &pt->x);
						}
					}
				}
				/* set new parent matrix */
				copy_m4_m4(gpl->inverse, cur_mat);
			}
		}
	}
}
/* ******************************************************** */
/* GP Object Stuff */

/* Helper function to create new OB_GPENCIL Object */
Object *ED_add_gpencil_object(bContext *C, Scene *scene, const float loc[3])
{
	float rot[3] = {0.0f};

	Object *ob = ED_object_add_type(C, OB_GPENCIL, NULL, loc, rot, false, scene->lay);

	/* define size */
	BKE_object_obdata_size_init(ob, GP_OBGPENCIL_DEFAULT_SIZE);
	/* create default brushes and colors */
	ED_gpencil_add_defaults(C);

	return ob;
}

/* Helper function to create default colors and drawing brushes */
void ED_gpencil_add_defaults(bContext *C)
{
	Main *bmain = CTX_data_main(C);
	Object *ob = CTX_data_active_object(C);
	ToolSettings *ts = CTX_data_tool_settings(C);

	/* first try to reuse default material */
	if (ob->actcol > 0) {
		Material *ma = give_current_material(ob, ob->actcol);
		if ((ma) && (ma->gp_style == NULL)) {
			BKE_material_init_gpencil_settings(ma);
		}
	}

	/* ensure color exist */
	BKE_gpencil_material_ensure(bmain, ob);

	Paint *paint = BKE_brush_get_gpencil_paint(ts);
	/* if not exist, create a new one */
	if (paint->brush == NULL) {
		/* create new brushes */
		BKE_brush_gpencil_presets(C);
	}

}

/* ******************************************************** */
/* Vertex Groups */

/* assign points to vertex group */
void ED_gpencil_vgroup_assign(bContext *C, Object *ob, float weight)
{
	const int def_nr = ob->actdef - 1;
	if (!BLI_findlink(&ob->defbase, def_nr))
		return;

	CTX_DATA_BEGIN(C, bGPDstroke *, gps, editable_gpencil_strokes)
	{
		if (gps->flag & GP_STROKE_SELECT) {
			for (int i = 0; i < gps->totpoints; i++) {
				bGPDspoint *pt = &gps->points[i];
				MDeformVert *dvert = &gps->dvert[i];
				if (pt->flag & GP_SPOINT_SELECT) {
					BKE_gpencil_vgroup_add_point_weight(dvert, def_nr, weight);
				}
			}
		}
	}
	CTX_DATA_END;
}

/* remove points from vertex group */
void ED_gpencil_vgroup_remove(bContext *C, Object *ob)
{
	const int def_nr = ob->actdef - 1;
	if (!BLI_findlink(&ob->defbase, def_nr))
		return;

	CTX_DATA_BEGIN(C, bGPDstroke *, gps, editable_gpencil_strokes)
	{
		for (int i = 0; i < gps->totpoints; i++) {
			bGPDspoint *pt = &gps->points[i];
			MDeformVert *dvert = &gps->dvert[i];

			if ((pt->flag & GP_SPOINT_SELECT) && (dvert->totweight > 0)) {
				BKE_gpencil_vgroup_remove_point_weight(dvert, def_nr);
			}
		}
	}
	CTX_DATA_END;
}

/* select points of vertex group */
void ED_gpencil_vgroup_select(bContext *C, Object *ob)
{
	const int def_nr = ob->actdef - 1;
	if (!BLI_findlink(&ob->defbase, def_nr))
		return;

	CTX_DATA_BEGIN(C, bGPDstroke *, gps, editable_gpencil_strokes)
	{
		for (int i = 0; i < gps->totpoints; i++) {
			bGPDspoint *pt = &gps->points[i];
			MDeformVert *dvert = &gps->dvert[i];

			if (BKE_gpencil_vgroup_use_index(dvert, def_nr) > -1.0f) {
				pt->flag |= GP_SPOINT_SELECT;
				gps->flag |= GP_STROKE_SELECT;
			}
		}
	}
	CTX_DATA_END;
}

/* unselect points of vertex group */
void ED_gpencil_vgroup_deselect(bContext *C, Object *ob)
{
	const int def_nr = ob->actdef - 1;
	if (!BLI_findlink(&ob->defbase, def_nr))
		return;

	CTX_DATA_BEGIN(C, bGPDstroke *, gps, editable_gpencil_strokes)
	{
		for (int i = 0; i < gps->totpoints; i++) {
			bGPDspoint *pt = &gps->points[i];
			MDeformVert *dvert = &gps->dvert[i];

			if (BKE_gpencil_vgroup_use_index(dvert, def_nr) > -1.0f) {
				pt->flag &= ~GP_SPOINT_SELECT;
				gps->flag |= GP_STROKE_SELECT;
			}
		}
	}
	CTX_DATA_END;
}

/* ******************************************************** */
/* Cursor drawing */

/* check if cursor is in drawing region */
static bool gp_check_cursor_region(bContext *C, int mval[2])
{
	ARegion *ar = CTX_wm_region(C);
	ScrArea *sa = CTX_wm_area(C);
	/* TODO: add more spacetypes */
	if (!ELEM(sa->spacetype, SPACE_VIEW3D)) {
		return false;
	}
	if ((ar) && (ar->regiontype != RGN_TYPE_WINDOW)) {
		return false;
	}
	else if (ar) {
		rcti region_rect;

		/* Perform bounds check using  */
		ED_region_visible_rect(ar, &region_rect);
		return BLI_rcti_isect_pt_v(&region_rect, mval);
	}
	else {
		return false;
	}
}

/* draw eraser cursor */
void ED_gpencil_brush_draw_eraser(Brush *brush, int x, int y)
{
	short radius = (short)brush->size;

	GPUVertFormat *format = immVertexFormat();
	const uint shdr_pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
	immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);

	glEnable(GL_LINE_SMOOTH);
	glEnable(GL_BLEND);
	glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA);

	immUniformColor4ub(255, 100, 100, 20);
	imm_draw_circle_fill_2d(shdr_pos, x, y, radius, 40);

	immUnbindProgram();

	immBindBuiltinProgram(GPU_SHADER_2D_LINE_DASHED_UNIFORM_COLOR);

	float viewport_size[4];
	glGetFloatv(GL_VIEWPORT, viewport_size);
	immUniform2f("viewport_size", viewport_size[2], viewport_size[3]);

	immUniformColor4f(1.0f, 0.39f, 0.39f, 0.78f);
	immUniform1i("colors_len", 0);  /* "simple" mode */
	immUniform1f("dash_width", 12.0f);
	immUniform1f("dash_factor", 0.5f);

	imm_draw_circle_wire_2d(shdr_pos, x, y, radius,
		/* XXX Dashed shader gives bad results with sets of small segments currently,
		*     temp hack around the issue. :( */
		max_ii(8, radius / 2));  /* was fixed 40 */

	immUnbindProgram();

	glDisable(GL_BLEND);
	glDisable(GL_LINE_SMOOTH);
}

/* Helper callback for drawing the cursor itself */
static void gp_brush_drawcursor(bContext *C, int x, int y, void *customdata)
{
	Main *bmain = CTX_data_main(C);
	Scene *scene = CTX_data_scene(C);
	Object *ob = CTX_data_active_object(C);
	ARegion *ar = CTX_wm_region(C);

	GP_BrushEdit_Settings *gset = &scene->toolsettings->gp_sculpt;
	bGPdata *gpd = ED_gpencil_data_get_active(C);
	GP_EditBrush_Data *brush = NULL;
	Brush *paintbrush = NULL;
	Material *ma = NULL;
	MaterialGPencilStyle *gp_style = NULL;
	int *last_mouse_position = customdata;

	if ((gpd) && (gpd->flag & GP_DATA_STROKE_WEIGHTMODE)) {
		brush = &gset->brush[gset->weighttype];
	}
	else {
		brush = &gset->brush[gset->brushtype];
	}

	/* default radius and color */
	float color[3] = {1.0f, 1.0f, 1.0f};
	float darkcolor[3];
	float radius = 3.0f;

	int mval[2] = {x, y};
	/* check if cursor is in drawing region and has valid datablock */
	if ((!gp_check_cursor_region(C, mval)) || (gpd == NULL)) {
		return;
	}

	/* for paint use paint brush size and color */
	if (gpd->flag & GP_DATA_STROKE_PAINTMODE) {
		paintbrush = BKE_brush_getactive_gpencil(scene->toolsettings);
		/* while drawing hide */
		if ((gpd->runtime.sbuffer_size > 0) &&
		    (paintbrush) && ((paintbrush->gpencil_settings->flag & GP_BRUSH_STABILIZE_MOUSE) == 0) &&
		    ((paintbrush->gpencil_settings->flag & GP_BRUSH_STABILIZE_MOUSE_TEMP) == 0))
		{
			return;
		}

		if (paintbrush) {
			if ((paintbrush->gpencil_settings->flag & GP_BRUSH_ENABLE_CURSOR) == 0) {
				return;
			}

			/* eraser has special shape and use a different shader program */
			if (paintbrush->gpencil_settings->brush_type == GP_BRUSH_TYPE_ERASE) {
				ED_gpencil_brush_draw_eraser(paintbrush, x, y);
				return;
			}

			/* get current drawing color */
			ma = BKE_gpencil_get_material_from_brush(paintbrush);
			if (ma == NULL) {
				BKE_gpencil_material_ensure(bmain, ob);
				/* assign the first material to the brush */
				ma = give_current_material(ob, 1);
				paintbrush->gpencil_settings->material = ma;
			}
			gp_style = ma->gp_style;

			/* after some testing, display the size of the brush is not practical because
			 * is too disruptive and the size of cursor does not change with zoom factor.
			 * The decision was to use a fix size, instead of paintbrush->thickness value.
			 */
			if ((gp_style) && (GPENCIL_PAINT_MODE(gpd)) &&
			    ((paintbrush->gpencil_settings->flag & GP_BRUSH_STABILIZE_MOUSE) == 0) &&
			    ((paintbrush->gpencil_settings->flag & GP_BRUSH_STABILIZE_MOUSE_TEMP) == 0) &&
			    (paintbrush->gpencil_settings->brush_type == GP_BRUSH_TYPE_DRAW))
			{
				radius = 2.0f;
				copy_v3_v3(color, gp_style->stroke_rgba);
			}
			else {
				radius = 5.0f;
				copy_v3_v3(color, paintbrush->add_col);
			}
		}
		else {
			return;
		}
	}

	/* for sculpt use sculpt brush size */
	if (GPENCIL_SCULPT_OR_WEIGHT_MODE(gpd)) {
		if (brush) {
			if ((brush->flag & GP_EDITBRUSH_FLAG_ENABLE_CURSOR) == 0) {
				return;
			}

			radius = brush->size;
			if (brush->flag & (GP_EDITBRUSH_FLAG_INVERT | GP_EDITBRUSH_FLAG_TMP_INVERT)) {
				copy_v3_v3(color, brush->curcolor_sub);
			}
			else {
				copy_v3_v3(color, brush->curcolor_add);
			}
		}
	}

	/* draw icon */
	GPUVertFormat *format = immVertexFormat();
	uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
	immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);

	glEnable(GL_LINE_SMOOTH);
	glEnable(GL_BLEND);

	/* Inner Ring: Color from UI panel */
	immUniformColor4f(color[0], color[1], color[2], 0.8f);
	if ((gp_style) && (GPENCIL_PAINT_MODE(gpd)) &&
	    ((paintbrush->gpencil_settings->flag & GP_BRUSH_STABILIZE_MOUSE) == 0) &&
	    ((paintbrush->gpencil_settings->flag & GP_BRUSH_STABILIZE_MOUSE_TEMP) == 0) &&
	    (paintbrush->gpencil_settings->brush_type == GP_BRUSH_TYPE_DRAW))
	{
		imm_draw_circle_fill_2d(pos, x, y, radius, 40);
	}
	else {
		imm_draw_circle_wire_2d(pos, x, y, radius, 40);
	}

	/* Outer Ring: Dark color for contrast on light backgrounds (e.g. gray on white) */
	mul_v3_v3fl(darkcolor, color, 0.40f);
	immUniformColor4f(darkcolor[0], darkcolor[1], darkcolor[2], 0.8f);
	imm_draw_circle_wire_2d(pos, x, y, radius + 1, 40);

	glDisable(GL_BLEND);
	glDisable(GL_LINE_SMOOTH);

	/* Draw line for lazy mouse */
	if ((last_mouse_position) &&
	    (paintbrush->gpencil_settings->flag & GP_BRUSH_STABILIZE_MOUSE_TEMP))
	{
		glEnable(GL_LINE_SMOOTH);
		glEnable(GL_BLEND);

		copy_v3_v3(color, paintbrush->add_col);
		immUniformColor4f(color[0], color[1], color[2], 0.8f);

		immBegin(GPU_PRIM_LINES, 2);
		immVertex2f(pos, x, y);
		immVertex2f(
		        pos,
		        last_mouse_position[0] + ar->winrct.xmin,
		        last_mouse_position[1] + ar->winrct.ymin);
		immEnd();

		glDisable(GL_BLEND);
		glDisable(GL_LINE_SMOOTH);
	}

	immUnbindProgram();
}

/* Turn brush cursor in on/off */
void ED_gpencil_toggle_brush_cursor(bContext *C, bool enable, void *customdata)
{
	Scene *scene = CTX_data_scene(C);
	GP_BrushEdit_Settings *gset = &scene->toolsettings->gp_sculpt;
	int *lastpost = customdata;

	if (gset->paintcursor && !enable) {
		/* clear cursor */
		WM_paint_cursor_end(CTX_wm_manager(C), gset->paintcursor);
		gset->paintcursor = NULL;
	}
	else if (enable) {
		/* in some situations cursor could be duplicated, so it is better disable first if exist */
		if (gset->paintcursor) {
			/* clear cursor */
			WM_paint_cursor_end(CTX_wm_manager(C), gset->paintcursor);
			gset->paintcursor = NULL;
		}
		/* enable cursor */
		gset->paintcursor = WM_paint_cursor_activate(CTX_wm_manager(C),
		                                             NULL,
		                                             gp_brush_drawcursor,
		                                             (lastpost) ? customdata : NULL);
	}
}

/* verify if is using the right brush */
static void gpencil_verify_brush_type(bContext *C, int newmode)
{
	ToolSettings *ts = CTX_data_tool_settings(C);
	GP_BrushEdit_Settings *gset = &ts->gp_sculpt;

	switch (newmode) {
		case OB_MODE_GPENCIL_SCULPT:
			gset->flag &= ~GP_BRUSHEDIT_FLAG_WEIGHT_MODE;
			if ((gset->brushtype < 0) || (gset->brushtype >= GP_EDITBRUSH_TYPE_WEIGHT)) {
				gset->brushtype = GP_EDITBRUSH_TYPE_PUSH;
			}
			break;
		case OB_MODE_GPENCIL_WEIGHT:
			gset->flag |= GP_BRUSHEDIT_FLAG_WEIGHT_MODE;
			if ((gset->weighttype < GP_EDITBRUSH_TYPE_WEIGHT) || (gset->weighttype >= TOT_GP_EDITBRUSH_TYPES)) {
				gset->weighttype = GP_EDITBRUSH_TYPE_WEIGHT;
			}
			break;
		default:
			break;
	}
}

/* set object modes */
void ED_gpencil_setup_modes(bContext *C, bGPdata *gpd, int newmode)
{
	if (!gpd) {
		return;
	}

	switch (newmode) {
		case OB_MODE_GPENCIL_EDIT:
			gpd->flag |= GP_DATA_STROKE_EDITMODE;
			gpd->flag &= ~GP_DATA_STROKE_PAINTMODE;
			gpd->flag &= ~GP_DATA_STROKE_SCULPTMODE;
			gpd->flag &= ~GP_DATA_STROKE_WEIGHTMODE;
			ED_gpencil_toggle_brush_cursor(C, false, NULL);
			break;
		case OB_MODE_GPENCIL_PAINT:
			gpd->flag &= ~GP_DATA_STROKE_EDITMODE;
			gpd->flag |= GP_DATA_STROKE_PAINTMODE;
			gpd->flag &= ~GP_DATA_STROKE_SCULPTMODE;
			gpd->flag &= ~GP_DATA_STROKE_WEIGHTMODE;
			ED_gpencil_toggle_brush_cursor(C, true, NULL);
			break;
		case OB_MODE_GPENCIL_SCULPT:
			gpd->flag &= ~GP_DATA_STROKE_EDITMODE;
			gpd->flag &= ~GP_DATA_STROKE_PAINTMODE;
			gpd->flag |= GP_DATA_STROKE_SCULPTMODE;
			gpd->flag &= ~GP_DATA_STROKE_WEIGHTMODE;
			gpencil_verify_brush_type(C, OB_MODE_GPENCIL_SCULPT);
			ED_gpencil_toggle_brush_cursor(C, true, NULL);
			break;
		case OB_MODE_GPENCIL_WEIGHT:
			gpd->flag &= ~GP_DATA_STROKE_EDITMODE;
			gpd->flag &= ~GP_DATA_STROKE_PAINTMODE;
			gpd->flag &= ~GP_DATA_STROKE_SCULPTMODE;
			gpd->flag |= GP_DATA_STROKE_WEIGHTMODE;
			gpencil_verify_brush_type(C, OB_MODE_GPENCIL_WEIGHT);
			ED_gpencil_toggle_brush_cursor(C, true, NULL);
			break;
		default:
			gpd->flag &= ~GP_DATA_STROKE_EDITMODE;
			gpd->flag &= ~GP_DATA_STROKE_PAINTMODE;
			gpd->flag &= ~GP_DATA_STROKE_SCULPTMODE;
			gpd->flag &= ~GP_DATA_STROKE_WEIGHTMODE;
			ED_gpencil_toggle_brush_cursor(C, false, NULL);
			break;
	}
}

/* helper to convert 2d to 3d for simple drawing buffer */
static void gpencil_stroke_convertcoords(ARegion *ar, const tGPspoint *point2D, float origin[3], float out[3])
{
	float mval_f[2] = { (float)point2D->x, (float)point2D->y };
	float mval_prj[2];
	float rvec[3], dvec[3];
	float zfac;

	copy_v3_v3(rvec, origin);

	zfac = ED_view3d_calc_zfac(ar->regiondata, rvec, NULL);

	if (ED_view3d_project_float_global(ar, rvec, mval_prj, V3D_PROJ_TEST_NOP) == V3D_PROJ_RET_OK) {
		sub_v2_v2v2(mval_f, mval_prj, mval_f);
		ED_view3d_win_to_delta(ar, mval_f, dvec, zfac);
		sub_v3_v3v3(out, rvec, dvec);
	}
	else {
		zero_v3(out);
	}
}

/* convert 2d tGPspoint to 3d bGPDspoint */
void ED_gpencil_tpoint_to_point(ARegion *ar, float origin[3], const tGPspoint *tpt, bGPDspoint *pt)
{
	float p3d[3];
	/* conversion to 3d format */
	gpencil_stroke_convertcoords(ar, tpt, origin, p3d);
	copy_v3_v3(&pt->x, p3d);

	pt->pressure = tpt->pressure;
	pt->strength = tpt->strength;
	pt->uv_fac = tpt->uv_fac;
	pt->uv_rot = tpt->uv_rot;
}

/* texture coordinate utilities */
void ED_gpencil_calc_stroke_uv(Object *ob, bGPDstroke *gps)
{
	if (gps == NULL) {
		return;
	}
	MaterialGPencilStyle *gp_style = BKE_material_gpencil_settings_get(ob, gps->mat_nr + 1);
	float pixsize;
	if (gp_style) {
		pixsize = gp_style->texture_pixsize / 1000000.0f;
	}
	else {
		/* use this value by default */
		pixsize = 0.000100f;
	}
	pixsize = MAX2(pixsize, 0.0000001f);

	bGPDspoint *pt = NULL;
	bGPDspoint *ptb = NULL;
	int i;
	float totlen = 0;

	/* first read all points and calc distance */
	for (i = 0; i < gps->totpoints; i++) {
		pt = &gps->points[i];
		/* first point */
		if (i == 0) {
			pt->uv_fac = 0.0f;
			continue;
		}

		ptb = &gps->points[i - 1];
		totlen += len_v3v3(&pt->x, &ptb->x) / pixsize;
		pt->uv_fac = totlen;
	}
	/* normalize the distance using a factor */
	float factor;
	/* if image, use texture width */
	if ((gp_style) && (gp_style->sima)) {
		factor = gp_style->sima->gen_x;
	}
	else {
		factor = totlen;
	}
	for (i = 0; i < gps->totpoints; i++) {
		pt = &gps->points[i];
		pt->uv_fac /= factor;
	}
}

/* recalc uv for any stroke using the material */
void ED_gpencil_update_color_uv(Main *bmain, Material *mat)
{
	Material *gps_ma = NULL;
	/* read all strokes  */
	for (Object *ob = bmain->object.first; ob; ob = ob->id.next) {
		if (ob->type == OB_GPENCIL) {
			bGPdata *gpd = ob->data;
			if (gpd == NULL) {
				continue;
			}

			for (bGPDlayer *gpl = gpd->layers.first; gpl; gpl = gpl->next) {
				/* only editable and visible layers are considered */
				if (gpencil_layer_is_editable(gpl)) {
					for (bGPDframe *gpf = gpl->frames.first; gpf; gpf = gpf->next) {
						for (bGPDstroke *gps = gpf->strokes.first; gps; gps = gps->next) {
							/* check if it is editable */
							if (ED_gpencil_stroke_color_use(ob, gpl, gps) == false) {
								continue;
							}
							gps_ma = give_current_material(ob, gps->mat_nr + 1);
							/* update */
							if ((gps_ma) && (gps_ma == mat)) {
								ED_gpencil_calc_stroke_uv(ob, gps);
							}
						}
					}
				}
			}
		}
	}
}
/* ******************************************************** */