/*
 * ***** 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) 2001-2002 by NaN Holding BV.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): none yet.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/editors/space_view3d/view3d_snap.c
 *  \ingroup spview3d
 */


#include "MEM_guardedalloc.h"

#include "DNA_armature_types.h"
#include "DNA_object_types.h"

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

#include "BKE_action.h"
#include "BKE_armature.h"
#include "BKE_context.h"
#include "BKE_editmesh.h"
#include "BKE_layer.h"
#include "BKE_main.h"
#include "BKE_mball.h"
#include "BKE_object.h"
#include "BKE_report.h"
#include "BKE_tracking.h"

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

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

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

#include "ED_object.h"
#include "ED_transverts.h"
#include "ED_keyframing.h"
#include "ED_screen.h"

#include "view3d_intern.h"

static bool snap_curs_to_sel_ex(bContext *C, float cursor[3]);
static bool snap_calc_active_center(bContext *C, const bool select_only, float r_center[3]);


/* *********************** operators ******************** */

/** Snaps every individual object center to its nearest point on the grid. **/
static int snap_sel_to_grid_exec(bContext *C, wmOperator *UNUSED(op))
{
	Depsgraph *depsgraph = CTX_data_depsgraph(C);
	ViewLayer *view_layer_eval = DEG_get_evaluated_view_layer(depsgraph);
	Object *obedit = CTX_data_edit_object(C);
	Scene *scene = CTX_data_scene(C);
	RegionView3D *rv3d = CTX_wm_region_data(C);
	TransVertStore tvs = {NULL};
	TransVert *tv;
	float gridf, imat[3][3], bmat[3][3], vec[3];
	int a;

	gridf = rv3d->gridview;

	if (obedit) {
		ViewLayer *view_layer = CTX_data_view_layer(C);
		uint objects_len = 0;
		Object **objects = BKE_view_layer_array_from_objects_in_edit_mode_unique_data(view_layer, &objects_len);
		for (uint ob_index = 0; ob_index < objects_len; ob_index++) {
			obedit = objects[ob_index];
			if (ED_transverts_check_obedit(obedit)) {
				ED_transverts_create_from_obedit(&tvs, obedit, 0);
			}

			if (tvs.transverts_tot == 0) {
				continue;
			}

			copy_m3_m4(bmat, obedit->obmat);
			invert_m3_m3(imat, bmat);

			tv = tvs.transverts;
			for (a = 0; a < tvs.transverts_tot; a++, tv++) {
				copy_v3_v3(vec, tv->loc);
				mul_m3_v3(bmat, vec);
				add_v3_v3(vec, obedit->obmat[3]);
				vec[0] = gridf * floorf(0.5f + vec[0] / gridf);
				vec[1] = gridf * floorf(0.5f + vec[1] / gridf);
				vec[2] = gridf * floorf(0.5f + vec[2] / gridf);
				sub_v3_v3(vec, obedit->obmat[3]);

				mul_m3_v3(imat, vec);
				copy_v3_v3(tv->loc, vec);
			}

			ED_transverts_update_obedit(&tvs, obedit);
			ED_transverts_free(&tvs);
		}
		MEM_freeN(objects);
	}
	else {
		struct KeyingSet *ks = ANIM_get_keyingset_for_autokeying(scene, ANIM_KS_LOCATION_ID);

		FOREACH_SELECTED_EDITABLE_OBJECT_BEGIN(view_layer_eval, ob_eval)
		{
			Object *ob = DEG_get_original_object(ob_eval);
			if (ob->mode & OB_MODE_POSE) {
				bPoseChannel *pchan_eval;
				bArmature *arm_eval = ob_eval->data;

				invert_m4_m4(ob_eval->imat, ob_eval->obmat);

				for (pchan_eval = ob_eval->pose->chanbase.first; pchan_eval; pchan_eval = pchan_eval->next) {
					if (pchan_eval->bone->flag & BONE_SELECTED) {
						if (pchan_eval->bone->layer & arm_eval->layer) {
							if ((pchan_eval->bone->flag & BONE_CONNECTED) == 0) {
								float nLoc[3];

								/* get nearest grid point to snap to */
								copy_v3_v3(nLoc, pchan_eval->pose_mat[3]);
								/* We must operate in world space! */
								mul_m4_v3(ob_eval->obmat, nLoc);
								vec[0] = gridf * floorf(0.5f + nLoc[0] / gridf);
								vec[1] = gridf * floorf(0.5f + nLoc[1] / gridf);
								vec[2] = gridf * floorf(0.5f + nLoc[2] / gridf);
								/* Back in object space... */
								mul_m4_v3(ob_eval->imat, vec);

								/* Get location of grid point in pose space. */
								BKE_armature_loc_pose_to_bone(pchan_eval, vec, vec);

								/* adjust location on the original pchan*/
								bPoseChannel *pchan = BKE_pose_channel_find_name(ob->pose, pchan_eval->name);
								if ((pchan->protectflag & OB_LOCK_LOCX) == 0)
									pchan->loc[0] = vec[0];
								if ((pchan->protectflag & OB_LOCK_LOCY) == 0)
									pchan->loc[1] = vec[1];
								if ((pchan->protectflag & OB_LOCK_LOCZ) == 0)
									pchan->loc[2] = vec[2];

								/* auto-keyframing */
								ED_autokeyframe_pchan(C, scene, ob, pchan, ks);
							}
							/* if the bone has a parent and is connected to the parent,
							 * don't do anything - will break chain unless we do auto-ik.
							 */
						}
					}
				}
				ob->pose->flag |= (POSE_LOCKED | POSE_DO_UNLOCK);

				DEG_id_tag_update(&ob->id, OB_RECALC_DATA);
			}
			else {
				vec[0] = -ob_eval->obmat[3][0] + gridf * floorf(0.5f + ob_eval->obmat[3][0] / gridf);
				vec[1] = -ob_eval->obmat[3][1] + gridf * floorf(0.5f + ob_eval->obmat[3][1] / gridf);
				vec[2] = -ob_eval->obmat[3][2] + gridf * floorf(0.5f + ob_eval->obmat[3][2] / gridf);

				if (ob->parent) {
					float originmat[3][3];
					BKE_object_where_is_calc_ex(depsgraph, scene, NULL, ob, originmat);

					invert_m3_m3(imat, originmat);
					mul_m3_v3(imat, vec);
				}
				if ((ob->protectflag & OB_LOCK_LOCX) == 0)
					ob->loc[0] = ob_eval->loc[0] + vec[0];
				if ((ob->protectflag & OB_LOCK_LOCY) == 0)
					ob->loc[1] = ob_eval->loc[1] + vec[1];
				if ((ob->protectflag & OB_LOCK_LOCZ) == 0)
					ob->loc[2] = ob_eval->loc[2] + vec[2];

				/* auto-keyframing */
				ED_autokeyframe_object(C, scene, ob, ks);

				DEG_id_tag_update(&ob->id, OB_RECALC_OB);
			}
		}
		FOREACH_SELECTED_EDITABLE_OBJECT_END;
	}

	WM_event_add_notifier(C, NC_OBJECT | ND_TRANSFORM, NULL);

	return OPERATOR_FINISHED;
}

void VIEW3D_OT_snap_selected_to_grid(wmOperatorType *ot)
{
	/* identifiers */
	ot->name = "Snap Selection to Grid";
	ot->description = "Snap selected item(s) to their nearest grid division";
	ot->idname = "VIEW3D_OT_snap_selected_to_grid";

	/* api callbacks */
	ot->exec = snap_sel_to_grid_exec;
	ot->poll = ED_operator_region_view3d_active;

	/* flags */
	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO | OPTYPE_USE_EVAL_DATA;
}

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

/** Snaps the selection as a whole (use_offset=true) or each selected object to the given location.
 *
 * \param snap_target_global: a location in global space to snap to (eg. 3D cursor or active object).
 * \param use_offset: if the selected objects should maintain their relative offsets and be snapped by the selection
 *                    pivot point (median, active), or if every object origin should be snapped to the given location.
**/
static int snap_selected_to_location(bContext *C, const float snap_target_global[3], const bool use_offset)
{
	Depsgraph *depsgraph = CTX_data_depsgraph(C);
	Scene *scene = CTX_data_scene(C);
	Object *obedit = CTX_data_edit_object(C);
	Object *obact = CTX_data_active_object(C);
	View3D *v3d = CTX_wm_view3d(C);
	TransVertStore tvs = {NULL};
	TransVert *tv;
	float imat[3][3], bmat[3][3];
	float center_global[3];
	float offset_global[3];
	int a;

	if (use_offset) {
		if ((v3d && scene->toolsettings->transform_pivot_point == V3D_AROUND_ACTIVE) &&
		    snap_calc_active_center(C, true, center_global))
		{
			/* pass */
		}
		else {
			snap_curs_to_sel_ex(C, center_global);
		}
		sub_v3_v3v3(offset_global, snap_target_global, center_global);
	}

	if (obedit) {
		float snap_target_local[3];

		if (ED_transverts_check_obedit(obedit))
			ED_transverts_create_from_obedit(&tvs, obedit, 0);
		if (tvs.transverts_tot == 0)
			return OPERATOR_CANCELLED;

		copy_m3_m4(bmat, obedit->obmat);
		invert_m3_m3(imat, bmat);

		/* get the cursor in object space */
		sub_v3_v3v3(snap_target_local, snap_target_global, obedit->obmat[3]);
		mul_m3_v3(imat, snap_target_local);

		if (use_offset) {
			float offset_local[3];

			mul_v3_m3v3(offset_local, imat, offset_global);

			tv = tvs.transverts;
			for (a = 0; a < tvs.transverts_tot; a++, tv++) {
				add_v3_v3(tv->loc, offset_local);
			}
		}
		else {
			tv = tvs.transverts;
			for (a = 0; a < tvs.transverts_tot; a++, tv++) {
				copy_v3_v3(tv->loc, snap_target_local);
			}
		}

		ED_transverts_update_obedit(&tvs, obedit);
		ED_transverts_free(&tvs);
	}
	else if (obact && (obact->mode & OB_MODE_POSE)) {
		struct KeyingSet *ks = ANIM_get_keyingset_for_autokeying(scene, ANIM_KS_LOCATION_ID);

		bPoseChannel *pchan;
		bArmature *arm = obact->data;
		float snap_target_local[3];

		invert_m4_m4(obact->imat, obact->obmat);
		mul_v3_m4v3(snap_target_local, obact->imat, snap_target_global);

		for (pchan = obact->pose->chanbase.first; pchan; pchan = pchan->next) {
			if ((pchan->bone->flag & BONE_SELECTED) &&
			    (PBONE_VISIBLE(arm, pchan->bone)) &&
			    /* if the bone has a parent and is connected to the parent,
			     * don't do anything - will break chain unless we do auto-ik.
			     */
			    (pchan->bone->flag & BONE_CONNECTED) == 0)
			{
				pchan->bone->flag |= BONE_TRANSFORM;
			}
			else {
				pchan->bone->flag &= ~BONE_TRANSFORM;
			}
		}

		for (pchan = obact->pose->chanbase.first; pchan; pchan = pchan->next) {
			if ((pchan->bone->flag & BONE_TRANSFORM) &&
			    /* check that our parents not transformed (if we have one) */
			    ((pchan->bone->parent &&
			      BKE_armature_bone_flag_test_recursive(pchan->bone->parent, BONE_TRANSFORM)) == 0))
			{
				/* Get position in pchan (pose) space. */
				float cursor_pose[3];

				if (use_offset) {
					mul_v3_m4v3(cursor_pose, obact->obmat, pchan->pose_mat[3]);
					add_v3_v3(cursor_pose, offset_global);

					mul_m4_v3(obact->imat, cursor_pose);
					BKE_armature_loc_pose_to_bone(pchan, cursor_pose, cursor_pose);
				}
				else {
					BKE_armature_loc_pose_to_bone(pchan, snap_target_local, cursor_pose);
				}

				/* copy new position */
				if ((pchan->protectflag & OB_LOCK_LOCX) == 0)
					pchan->loc[0] = cursor_pose[0];
				if ((pchan->protectflag & OB_LOCK_LOCY) == 0)
					pchan->loc[1] = cursor_pose[1];
				if ((pchan->protectflag & OB_LOCK_LOCZ) == 0)
					pchan->loc[2] = cursor_pose[2];

				/* auto-keyframing */
				ED_autokeyframe_pchan(C, scene, obact, pchan, ks);
			}
		}

		for (pchan = obact->pose->chanbase.first; pchan; pchan = pchan->next) {
			pchan->bone->flag &= ~BONE_TRANSFORM;
		}

		obact->pose->flag |= (POSE_LOCKED | POSE_DO_UNLOCK);

		DEG_id_tag_update(&obact->id, OB_RECALC_DATA);
	}
	else {
		struct KeyingSet *ks = ANIM_get_keyingset_for_autokeying(scene, ANIM_KS_LOCATION_ID);
		Main *bmain = CTX_data_main(C);

		ListBase ctx_data_list;
		CollectionPointerLink *ctx_ob;
		Object *ob;

		CTX_data_selected_editable_objects(C, &ctx_data_list);

		/* reset flags */
		for (ob = bmain->object.first; ob; ob = ob->id.next) {
			ob->flag &= ~OB_DONE;
		}

		/* tag objects we're transforming */
		for (ctx_ob = ctx_data_list.first; ctx_ob; ctx_ob = ctx_ob->next) {
			ob = ctx_ob->ptr.data;
			ob->flag |= OB_DONE;
		}

		for (ctx_ob = ctx_data_list.first; ctx_ob; ctx_ob = ctx_ob->next) {
			ob = ctx_ob->ptr.data;

			if ((ob->parent && BKE_object_flag_test_recursive(ob->parent, OB_DONE)) == 0) {

				float cursor_parent[3];  /* parent-relative */

				if (use_offset) {
					add_v3_v3v3(cursor_parent, ob->obmat[3], offset_global);
				}
				else {
					copy_v3_v3(cursor_parent, snap_target_global);
				}

				sub_v3_v3(cursor_parent, ob->obmat[3]);

				if (ob->parent) {
					float originmat[3][3];
					BKE_object_where_is_calc_ex(depsgraph, scene, NULL, ob, originmat);

					invert_m3_m3(imat, originmat);
					mul_m3_v3(imat, cursor_parent);
				}
				if ((ob->protectflag & OB_LOCK_LOCX) == 0)
					ob->loc[0] += cursor_parent[0];
				if ((ob->protectflag & OB_LOCK_LOCY) == 0)
					ob->loc[1] += cursor_parent[1];
				if ((ob->protectflag & OB_LOCK_LOCZ) == 0)
					ob->loc[2] += cursor_parent[2];

				/* auto-keyframing */
				ED_autokeyframe_object(C, scene, ob, ks);

				DEG_id_tag_update(&ob->id, OB_RECALC_OB);
			}
		}

		BLI_freelistN(&ctx_data_list);
	}

	WM_event_add_notifier(C, NC_OBJECT | ND_TRANSFORM, NULL);

	return OPERATOR_FINISHED;
}

static int snap_selected_to_cursor_exec(bContext *C, wmOperator *op)
{
	const bool use_offset = RNA_boolean_get(op->ptr, "use_offset");

	Scene *scene = CTX_data_scene(C);
	View3D *v3d = CTX_wm_view3d(C);

	const float *snap_target_global = ED_view3d_cursor3d_get(scene, v3d)->location;

	return snap_selected_to_location(C, snap_target_global, use_offset);
}

void VIEW3D_OT_snap_selected_to_cursor(wmOperatorType *ot)
{
	/* identifiers */
	ot->name = "Snap Selection to Cursor";
	ot->description = "Snap selected item(s) to the 3D cursor";
	ot->idname = "VIEW3D_OT_snap_selected_to_cursor";

	/* api callbacks */
	ot->exec = snap_selected_to_cursor_exec;
	ot->poll = ED_operator_view3d_active;

	/* flags */
	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO | OPTYPE_USE_EVAL_DATA;

	/* rna */
	RNA_def_boolean(ot->srna, "use_offset", 1, "Offset",
		"If the selection should be snapped as a whole or by each object center");
}

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

/** Snaps each selected object to the location of the active selected object. **/
static int snap_selected_to_active_exec(bContext *C, wmOperator *op)
{
	float snap_target_global[3];

	if (snap_calc_active_center(C, false, snap_target_global) == false) {
		BKE_report(op->reports, RPT_ERROR, "No active element found!");
		return OPERATOR_CANCELLED;
	}

	return snap_selected_to_location(C, snap_target_global, false);
}

void VIEW3D_OT_snap_selected_to_active(wmOperatorType *ot)
{
	/* identifiers */
	ot->name = "Snap Selection to Active";
	ot->description = "Snap selected item(s) to the active item";
	ot->idname = "VIEW3D_OT_snap_selected_to_active";

	/* api callbacks */
	ot->exec = snap_selected_to_active_exec;
	ot->poll = ED_operator_view3d_active;

	/* flags */
	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO | OPTYPE_USE_EVAL_DATA;
}


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

/** Snaps the 3D cursor location to its nearest point on the grid. **/
static int snap_curs_to_grid_exec(bContext *C, wmOperator *UNUSED(op))
{
	Scene *scene = CTX_data_scene(C);
	RegionView3D *rv3d = CTX_wm_region_data(C);
	View3D *v3d = CTX_wm_view3d(C);
	float gridf, *curs;

	gridf = rv3d->gridview;
	curs = ED_view3d_cursor3d_get(scene, v3d)->location;

	curs[0] = gridf * floorf(0.5f + curs[0] / gridf);
	curs[1] = gridf * floorf(0.5f + curs[1] / gridf);
	curs[2] = gridf * floorf(0.5f + curs[2] / gridf);

	WM_event_add_notifier(C, NC_SPACE | ND_SPACE_VIEW3D, v3d);  /* hrm */
	DEG_id_tag_update(&scene->id, DEG_TAG_COPY_ON_WRITE);

	return OPERATOR_FINISHED;
}

void VIEW3D_OT_snap_cursor_to_grid(wmOperatorType *ot)
{
	/* identifiers */
	ot->name = "Snap Cursor to Grid";
	ot->description = "Snap 3D cursor to the nearest grid division";
	ot->idname = "VIEW3D_OT_snap_cursor_to_grid";

	/* api callbacks */
	ot->exec = snap_curs_to_grid_exec;
	ot->poll = ED_operator_region_view3d_active;

	/* flags */
	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
}

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

/** Returns the center position of a tracking marker visible on the viewport (useful to snap to). **/
static void bundle_midpoint(Depsgraph *depsgraph, Scene *scene, Object *ob, float r_vec[3])
{
	MovieClip *clip = BKE_object_movieclip_get(scene, ob, false);
	MovieTracking *tracking;
	MovieTrackingObject *object;
	bool ok = false;
	float min[3], max[3], mat[4][4], pos[3], cammat[4][4];

	if (!clip)
		return;

	tracking = &clip->tracking;

	copy_m4_m4(cammat, ob->obmat);

	BKE_tracking_get_camera_object_matrix(depsgraph, scene, ob, mat);

	INIT_MINMAX(min, max);

	for (object = tracking->objects.first; object; object = object->next) {
		ListBase *tracksbase = BKE_tracking_object_get_tracks(tracking, object);
		MovieTrackingTrack *track = tracksbase->first;
		float obmat[4][4];

		if (object->flag & TRACKING_OBJECT_CAMERA) {
			copy_m4_m4(obmat, mat);
		}
		else {
			float imat[4][4];

			BKE_tracking_camera_get_reconstructed_interpolate(tracking, object, scene->r.cfra, imat);
			invert_m4(imat);

			mul_m4_m4m4(obmat, cammat, imat);
		}

		while (track) {
			if ((track->flag & TRACK_HAS_BUNDLE) && TRACK_SELECTED(track)) {
				ok = 1;
				mul_v3_m4v3(pos, obmat, track->bundle_pos);
				minmax_v3v3_v3(min, max, pos);
			}

			track = track->next;
		}
	}

	if (ok) {
		mid_v3_v3v3(r_vec, min, max);
	}
}

/** Snaps the 3D cursor location to the median point of the selection. **/
static bool snap_curs_to_sel_ex(bContext *C, float cursor[3])
{
	Depsgraph *depsgraph = CTX_data_depsgraph(C);
	ViewLayer *view_layer_eval = DEG_get_evaluated_view_layer(depsgraph);
	Object *obedit = CTX_data_edit_object(C);
	Scene *scene = CTX_data_scene(C);
	View3D *v3d = CTX_wm_view3d(C);
	TransVertStore tvs = {NULL};
	TransVert *tv;
	float bmat[3][3], vec[3], min[3], max[3], centroid[3];
	int count, a;

	count = 0;
	INIT_MINMAX(min, max);
	zero_v3(centroid);

	if (obedit) {
		if (ED_transverts_check_obedit(obedit))
			ED_transverts_create_from_obedit(&tvs, obedit, TM_ALL_JOINTS | TM_SKIP_HANDLES);

		if (tvs.transverts_tot == 0) {
			return false;
		}

		Object *obedit_eval = DEG_get_evaluated_object(depsgraph, obedit);
		copy_m3_m4(bmat, obedit_eval->obmat);

		tv = tvs.transverts;
		for (a = 0; a < tvs.transverts_tot; a++, tv++) {
			copy_v3_v3(vec, tv->loc);
			mul_m3_v3(bmat, vec);
			add_v3_v3(vec, obedit_eval->obmat[3]);
			add_v3_v3(centroid, vec);
			minmax_v3v3_v3(min, max, vec);
		}

		if (scene->toolsettings->transform_pivot_point == V3D_AROUND_CENTER_MEAN) {
			mul_v3_fl(centroid, 1.0f / (float)tvs.transverts_tot);
			copy_v3_v3(cursor, centroid);
		}
		else {
			mid_v3_v3v3(cursor, min, max);
		}

		ED_transverts_free(&tvs);
	}
	else {
		Object *obact = CTX_data_active_object(C);

		if (obact && (obact->mode & OB_MODE_POSE)) {
			Object *obact_eval = DEG_get_evaluated_object(depsgraph, obact);
			bArmature *arm = obact_eval->data;
			bPoseChannel *pchan;
			for (pchan = obact_eval->pose->chanbase.first; pchan; pchan = pchan->next) {
				if (arm->layer & pchan->bone->layer) {
					if (pchan->bone->flag & BONE_SELECTED) {
						copy_v3_v3(vec, pchan->pose_head);
						mul_m4_v3(obact_eval->obmat, vec);
						add_v3_v3(centroid, vec);
						minmax_v3v3_v3(min, max, vec);
						count++;
					}
				}
			}
		}
		else {
			FOREACH_SELECTED_OBJECT_BEGIN(view_layer_eval, ob_eval)
			{
				copy_v3_v3(vec, ob_eval->obmat[3]);

				/* special case for camera -- snap to bundles */
				if (ob_eval->type == OB_CAMERA) {
					/* snap to bundles should happen only when bundles are visible */
					if (v3d->flag2 & V3D_SHOW_RECONSTRUCTION) {
						bundle_midpoint(depsgraph, scene, DEG_get_original_object(ob_eval), vec);
					}
				}

				add_v3_v3(centroid, vec);
				minmax_v3v3_v3(min, max, vec);
				count++;
			}
			FOREACH_SELECTED_OBJECT_END;
		}

		if (count == 0) {
			return false;
		}

		if (scene->toolsettings->transform_pivot_point == V3D_AROUND_CENTER_MEAN) {
			mul_v3_fl(centroid, 1.0f / (float)count);
			copy_v3_v3(cursor, centroid);
		}
		else {
			mid_v3_v3v3(cursor, min, max);
		}
	}
	return true;
}

static int snap_curs_to_sel_exec(bContext *C, wmOperator *UNUSED(op))
{
	Scene *scene = CTX_data_scene(C);
	View3D *v3d = CTX_wm_view3d(C);
	float *curs;

	curs = ED_view3d_cursor3d_get(scene, v3d)->location;

	if (snap_curs_to_sel_ex(C, curs)) {
		WM_event_add_notifier(C, NC_SPACE | ND_SPACE_VIEW3D, v3d);
		DEG_id_tag_update(&scene->id, DEG_TAG_COPY_ON_WRITE);

		return OPERATOR_FINISHED;
	}
	else {
		return OPERATOR_CANCELLED;
	}
}

void VIEW3D_OT_snap_cursor_to_selected(wmOperatorType *ot)
{
	/* identifiers */
	ot->name = "Snap Cursor to Selected";
	ot->description = "Snap 3D cursor to the middle of the selected item(s)";
	ot->idname = "VIEW3D_OT_snap_cursor_to_selected";

	/* api callbacks */
	ot->exec = snap_curs_to_sel_exec;
	ot->poll = ED_operator_view3d_active;

	/* flags */
	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO | OPTYPE_USE_EVAL_DATA;
}

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

/** Calculates the center position of the active object in global space.
 *
 * Note: this could be exported to be a generic function.
 * see: calculateCenterActive
**/
static bool snap_calc_active_center(bContext *C, const bool select_only, float r_center[3])
{
	const Depsgraph *depsgraph = CTX_data_depsgraph(C);
	Object *obedit = CTX_data_edit_object(C);

	if (obedit) {
		Object *ob_edit_eval = DEG_get_evaluated_object(depsgraph, obedit);

		if (ED_object_editmode_calc_active_center(ob_edit_eval, select_only, r_center)) {
			mul_m4_v3(ob_edit_eval->obmat, r_center);
			return true;
		}
	}
	else {
		Object *ob = CTX_data_active_object(C);
		if (ob) {
			Object *ob_eval = DEG_get_evaluated_object(depsgraph, ob);

			if (ob->mode & OB_MODE_POSE) {
				bPoseChannel *pchan = BKE_pose_channel_active(ob_eval);
				if (pchan) {
					if (!select_only || (pchan->bone->flag & BONE_SELECTED)) {
						copy_v3_v3(r_center, pchan->pose_head);
						mul_m4_v3(ob_eval->obmat, r_center);
						return true;
					}
				}
			}
			else {

				if (!select_only || (ob_eval->flag & SELECT)) {
					copy_v3_v3(r_center, ob_eval->obmat[3]);
					return true;
				}
			}
		}
	}

	return false;
}

static int snap_curs_to_active_exec(bContext *C, wmOperator *UNUSED(op))
{
	Scene *scene = CTX_data_scene(C);
	View3D *v3d = CTX_wm_view3d(C);
	float *curs;

	curs = ED_view3d_cursor3d_get(scene, v3d)->location;

	if (snap_calc_active_center(C, false, curs)) {
		WM_event_add_notifier(C, NC_SPACE | ND_SPACE_VIEW3D, v3d);
		DEG_id_tag_update(&scene->id, DEG_TAG_COPY_ON_WRITE);

		return OPERATOR_FINISHED;
	}
	else {
		return OPERATOR_CANCELLED;
	}
}

void VIEW3D_OT_snap_cursor_to_active(wmOperatorType *ot)
{
	/* identifiers */
	ot->name = "Snap Cursor to Active";
	ot->description = "Snap 3D cursor to the active item";
	ot->idname = "VIEW3D_OT_snap_cursor_to_active";

	/* api callbacks */
	ot->exec = snap_curs_to_active_exec;
	ot->poll = ED_operator_view3d_active;

	/* flags */
	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO | OPTYPE_USE_EVAL_DATA;
}

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

/** Snaps the 3D cursor location to the origin. **/
static int snap_curs_to_center_exec(bContext *C, wmOperator *UNUSED(op))
{
	Scene *scene = CTX_data_scene(C);
	View3D *v3d = CTX_wm_view3d(C);
	float *curs;
	curs = ED_view3d_cursor3d_get(scene, v3d)->location;

	zero_v3(curs);

	WM_event_add_notifier(C, NC_SPACE | ND_SPACE_VIEW3D, v3d);
	DEG_id_tag_update(&scene->id, DEG_TAG_COPY_ON_WRITE);

	return OPERATOR_FINISHED;
}

void VIEW3D_OT_snap_cursor_to_center(wmOperatorType *ot)
{
	/* identifiers */
	ot->name = "Snap Cursor to Center";
	ot->description = "Snap 3D cursor to the world origin";
	ot->idname = "VIEW3D_OT_snap_cursor_to_center";

	/* api callbacks */
	ot->exec = snap_curs_to_center_exec;
	ot->poll = ED_operator_view3d_active;

	/* flags */
	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
}

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

/** Calculates the bounding box corners (min and max) for \a obedit. The returned values are in global space. **/
bool ED_view3d_minmax_verts(Object *obedit, float r_min[3], float r_max[3])
{
	TransVertStore tvs = {NULL};
	TransVert *tv;
	float centroid[3], vec[3], bmat[3][3];

	/* Metaballs are an exception. */
	if (obedit->type == OB_MBALL) {
		float ob_min[3], ob_max[3];
		bool changed;

		changed = BKE_mball_minmax_ex(obedit->data, ob_min, ob_max, obedit->obmat, SELECT);
		if (changed) {
			minmax_v3v3_v3(r_min, r_max, ob_min);
			minmax_v3v3_v3(r_min, r_max, ob_max);
		}
		return changed;
	}

	if (ED_transverts_check_obedit(obedit))
		ED_transverts_create_from_obedit(&tvs, obedit, TM_ALL_JOINTS);

	if (tvs.transverts_tot == 0)
		return false;

	copy_m3_m4(bmat, obedit->obmat);

	tv = tvs.transverts;
	for (int a = 0; a < tvs.transverts_tot; a++, tv++) {
		copy_v3_v3(vec, (tv->flag & TX_VERT_USE_MAPLOC) ? tv->maploc : tv->loc);
		mul_m3_v3(bmat, vec);
		add_v3_v3(vec, obedit->obmat[3]);
		add_v3_v3(centroid, vec);
		minmax_v3v3_v3(r_min, r_max, vec);
	}

	ED_transverts_free(&tvs);

	return true;
}