mesh_bsurfaces.py

                self.using_external_curves = True

                bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')


            #### Make sure there are no objects left from erroneous executions of this operator, with the reserved names used here.
            for o in bpy.data.objects:
                if o.name.find("SURFSKIO_") != -1:
                    bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
                    bpy.data.objects[o.name].select = True
                    bpy.context.scene.objects.active = bpy.data.objects[o.name]

                    bpy.ops.object.delete()


            bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
            bpy.data.objects[self.original_curve.name].select = True
            bpy.context.scene.objects.active = bpy.data.objects[self.original_curve.name]

            bpy.ops.object.duplicate('INVOKE_REGION_WIN')


            self.temporary_curve = bpy.context.scene.objects.active


            # Deselect all points of the curve
            bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')
            bpy.ops.curve.select_all('INVOKE_REGION_WIN', action='DESELECT')
            bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')



            # Delete splines with only a single isolated point.
            for i in range(len(self.temporary_curve.data.splines)):
                sp = self.temporary_curve.data.splines[i]

                if len(sp.bezier_points) == 1:
                    sp.bezier_points[0].select_control_point = True

            bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')
            bpy.ops.curve.delete(type='VERT')
            bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')


            bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
            bpy.data.objects[self.temporary_curve.name].select = True
            bpy.context.scene.objects.active = bpy.data.objects[self.temporary_curve.name]

            #### Set a minimum number of points for crosshatch
            minimum_points_num = 15

            bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')
            # Check if the number of points of each curve has at least the number of points of minimum_points_num, which is a bit more than the face-loops limit. If not, subdivide to reach at least that number of ponts.
            for i in range(len(self.temporary_curve.data.splines)):
                sp = self.temporary_curve.data.splines[i]

                if len(sp.bezier_points) < minimum_points_num:
                    for bp in sp.bezier_points:
                        bp.select_control_point = True

                    if (len(sp.bezier_points) - 1) != 0:
                        subdivide_cuts = int((minimum_points_num - len(sp.bezier_points)) / (len(sp.bezier_points) - 1)) + 1 # Formula to get the number of cuts that will make a curve of N number of points have near to "minimum_points_num" points, when subdividing with this number of cuts.
                    else:
                        subdivide_cuts = 0


                    bpy.ops.curve.subdivide('INVOKE_REGION_WIN', number_cuts = subdivide_cuts)
                    bpy.ops.curve.select_all('INVOKE_REGION_WIN', action='DESELECT')

            bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')



            # Detect if the strokes are a crosshatch and do it if it is.
            self.crosshatch_surface_invoke(self.temporary_curve)



            if not self.is_crosshatch:
                bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
                bpy.data.objects[self.temporary_curve.name].select = True
                bpy.context.scene.objects.active = bpy.data.objects[self.temporary_curve.name]

                bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')

                #### Set a minimum number of points for rectangular surfaces.
                minimum_points_num = 60

                # Check if the number of points of each curve has at least the number of points of minimum_points_num, which is a bit more than the face-loops limit. If not, subdivide to reach at least that number of ponts.
                for i in range(len(self.temporary_curve.data.splines)):
                    sp = self.temporary_curve.data.splines[i]

                    if len(sp.bezier_points) < minimum_points_num:
                        for bp in sp.bezier_points:
                            bp.select_control_point = True

                        if (len(sp.bezier_points) - 1) != 0:
                            subdivide_cuts = int((minimum_points_num - len(sp.bezier_points)) / (len(sp.bezier_points) - 1)) + 1 # Formula to get the number of cuts that will make a curve of N number of points have near to "minimum_points_num" points, when subdividing with this number of cuts.
                        else:
                            subdivide_cuts = 0


                        bpy.ops.curve.subdivide('INVOKE_REGION_WIN', number_cuts = subdivide_cuts)
                        bpy.ops.curve.select_all('INVOKE_REGION_WIN', action='DESELECT')

                bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')




            # Save coordinates of the actual strokes (as the "last saved splines").
            for sp_idx in range(len(self.temporary_curve.data.splines)):
                self.last_strokes_splines_coords.append([])
                for bp_idx in range(len(self.temporary_curve.data.splines[sp_idx].bezier_points)):
                    coords = self.temporary_curve.matrix_world * self.temporary_curve.data.splines[sp_idx].bezier_points[bp_idx].co
                    self.last_strokes_splines_coords[sp_idx].append([coords[0], coords[1], coords[2]])


            # Check for cyclic splines, put the first and last points in the middle of their actual positions.
            for sp_idx in range(len(self.temporary_curve.data.splines)):
                if self.temporary_curve.data.splines[sp_idx].use_cyclic_u == True:
                    first_p_co = self.last_strokes_splines_coords[sp_idx][0]
                    last_p_co = self.last_strokes_splines_coords[sp_idx][len(self.last_strokes_splines_coords[sp_idx]) - 1]

                    target_co = [(first_p_co[0] + last_p_co[0]) / 2, (first_p_co[1] + last_p_co[1]) / 2, (first_p_co[2] + last_p_co[2]) / 2]

                    self.last_strokes_splines_coords[sp_idx][0] = target_co
                    self.last_strokes_splines_coords[sp_idx][len(self.last_strokes_splines_coords[sp_idx]) - 1] = target_co

            tuple(self.last_strokes_splines_coords)



            # Estimation of the average length of the segments between each point of the grease pencil strokes. Will be useful to determine whether a curve should be made "Cyclic".
            segments_lengths_sum = 0
            segments_count = 0
            random_spline = self.temporary_curve.data.splines[0].bezier_points
            for i in range(0, len(random_spline)):
                if i != 0 and len(random_spline) - 1 >= i:
                    segments_lengths_sum += (random_spline[i - 1].co - random_spline[i].co).length
                    segments_count += 1

            self.average_gp_segment_length = segments_lengths_sum / segments_count


            #### Delete temporary strokes curve object
            bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
            bpy.data.objects[self.temporary_curve.name].select = True
            bpy.context.scene.objects.active = bpy.data.objects[self.temporary_curve.name]

            bpy.ops.object.delete()


            bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
            bpy.data.objects[self.main_object.name].select = True
            bpy.context.scene.objects.active = bpy.data.objects[self.main_object.name]

            bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')


            self.execute(context)
            bpy.context.user_preferences.edit.use_global_undo = False # Set again since "execute()" will turn it again to its initial value.


            #### If "Keep strokes" option is not active, delete original strokes curve object.
            if (not self.stopping_errors and not self.keep_strokes) or self.is_crosshatch:
                bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')
                bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
                bpy.data.objects[self.original_curve.name].select = True
                bpy.context.scene.objects.active = bpy.data.objects[self.original_curve.name]

                bpy.ops.object.delete()

                bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
                bpy.data.objects[self.main_object.name].select = True
                bpy.context.scene.objects.active = bpy.data.objects[self.main_object.name]

                bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')



            #### Delete grease pencil strokes.
            if self.strokes_type == "GP_STROKES" and not self.stopping_errors:
                bpy.ops.gpencil.active_frame_delete('INVOKE_REGION_WIN')


            bpy.context.user_preferences.edit.use_global_undo = self.initial_global_undo_state


            if not self.stopping_errors:
                return {"FINISHED"}
            else:
                return{"CANCELLED"}

        elif self.strokes_type == "SELECTION_ALONE":
            self.is_fill_faces = True

            created_faces_count = self.fill_with_faces(self.main_object)

            bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')

            if created_faces_count == 0:
                self.report({'WARNING'}, "There aren't any strokes.")
                return {"CANCELLED"}
            else:
                return {"FINISHED"}




        elif self.strokes_type == "EXTERNAL_NO_CURVE":
            self.report({'WARNING'}, "The secondary object is not a Curve.")
            return{"CANCELLED"}

        elif self.strokes_type == "MORE_THAN_ONE_EXTERNAL":
            self.report({'WARNING'}, "There shouldn't be more than one secondary object selected.")
            return{"CANCELLED"}

        elif self.strokes_type == "SINGLE_GP_STROKE_NO_SELECTION" or self.strokes_type == "SINGLE_CURVE_STROKE_NO_SELECTION":
            self.report({'WARNING'}, "It's needed at least one stroke and one selection, or two strokes.")
            return{"CANCELLED"}

        elif self.strokes_type == "NO_STROKES":
            self.report({'WARNING'}, "There aren't any strokes.")
            return{"CANCELLED"}

        elif self.strokes_type == "CURVE_WITH_NON_BEZIER_SPLINES":
            self.report({'WARNING'}, "All splines must be Bezier.")
            return{"CANCELLED"}

        else:
            return{"CANCELLED"}


# Edit strokes operator.
class GPENCIL_OT_SURFSK_edit_strokes(bpy.types.Operator):
    bl_idname = "gpencil.surfsk_edit_strokes"
    bl_label = "Bsurfaces edit strokes"
    bl_description = "Edit the grease pencil strokes or curves used."


    def execute(self, context):
        #### Determine the type of the strokes.
        self.strokes_type = get_strokes_type(self.main_object)
        #### Check if strokes are grease pencil strokes or a curves object.
        selected_objs = bpy.context.selected_objects
        if self.strokes_type == "EXTERNAL_CURVE" or self.strokes_type == "SINGLE_CURVE_STROKE_NO_SELECTION":
            for ob in selected_objs:
                if ob != bpy.context.scene.objects.active:
                    curve_ob = ob

            bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')

            bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
            bpy.data.objects[curve_ob.name].select = True
            bpy.context.scene.objects.active = bpy.data.objects[curve_ob.name]

            bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')
        elif self.strokes_type == "GP_STROKES" or self.strokes_type == "SINGLE_GP_STROKE_NO_SELECTION":
            #### Convert grease pencil strokes to curve.
            bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')
            bpy.ops.gpencil.convert('INVOKE_REGION_WIN', type='CURVE', use_link_strokes=False)
            for ob in bpy.context.selected_objects:
                    if ob != bpy.context.scene.objects.active and ob.name.startswith("GP_Layer"):
                        ob_gp_strokes = ob

            #ob_gp_strokes = bpy.context.object

            #### Delete grease pencil strokes.
            bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
            bpy.data.objects[self.main_object.name].select = True
            bpy.context.scene.objects.active = bpy.data.objects[self.main_object.name]

            bpy.ops.gpencil.active_frame_delete('INVOKE_REGION_WIN')


            #### Clean up curves.
            bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
            bpy.data.objects[ob_gp_strokes.name].select = True
            bpy.context.scene.objects.active = bpy.data.objects[ob_gp_strokes.name]

            curve_crv = ob_gp_strokes.data
            bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')
            bpy.ops.curve.spline_type_set('INVOKE_REGION_WIN', type="BEZIER")
            bpy.ops.curve.handle_type_set('INVOKE_REGION_WIN', type="AUTOMATIC")
            bpy.data.curves[curve_crv.name].show_handles = False
            bpy.data.curves[curve_crv.name].show_normal_face = False

        elif self.strokes_type == "EXTERNAL_NO_CURVE":
            self.report({'WARNING'}, "The secondary object is not a Curve.")
            return{"CANCELLED"}
        elif self.strokes_type == "MORE_THAN_ONE_EXTERNAL":
            self.report({'WARNING'}, "There shouldn't be more than one secondary object selected.")
            return{"CANCELLED"}
        elif self.strokes_type == "NO_STROKES" or self.strokes_type == "SELECTION_ALONE":
            self.report({'WARNING'}, "There aren't any strokes.")
            return{"CANCELLED"}
        else:
            return{"CANCELLED"}



    def invoke (self, context, event):
        self.main_object = bpy.context.object

        self.execute(context)

        return {"FINISHED"}




class CURVE_OT_SURFSK_reorder_splines(bpy.types.Operator):
    bl_idname = "curve.surfsk_reorder_splines"
    bl_label = "Bsurfaces reorder splines"
    bl_description = "Defines the order of the splines by using grease pencil strokes."
    bl_options = {'REGISTER', 'UNDO'}



    def execute(self, context):
        objects_to_delete = []
        #### Convert grease pencil strokes to curve.
        bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')
        bpy.ops.gpencil.convert('INVOKE_REGION_WIN', type='CURVE', use_link_strokes=False)
        for ob in bpy.context.selected_objects:
            if ob != bpy.context.scene.objects.active and ob.name.startswith("GP_Layer"):
                GP_strokes_curve = ob

        #GP_strokes_curve = bpy.context.object
        objects_to_delete.append(GP_strokes_curve)

        bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
        bpy.data.objects[GP_strokes_curve.name].select = True
        bpy.context.scene.objects.active = bpy.data.objects[GP_strokes_curve.name]


        bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')
        bpy.ops.curve.select_all('INVOKE_REGION_WIN', action='SELECT')
        bpy.ops.curve.subdivide('INVOKE_REGION_WIN', number_cuts = 100)
        bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')

        bpy.ops.object.duplicate('INVOKE_REGION_WIN')
        GP_strokes_mesh = bpy.context.object
        objects_to_delete.append(GP_strokes_mesh)

        GP_strokes_mesh.data.resolution_u = 1
        bpy.ops.object.convert(target='MESH', keep_original=False)


        bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
        bpy.data.objects[self.main_curve.name].select = True
        bpy.context.scene.objects.active = bpy.data.objects[self.main_curve.name]

        bpy.ops.object.duplicate('INVOKE_REGION_WIN')
        curves_duplicate_1 = bpy.context.object
        objects_to_delete.append(curves_duplicate_1)



        minimum_points_num = 500


        for x in range(round(minimum_points_num / 100)): # Some iterations since the subdivision operator has a limit of 100 subdivisions per iteration.
            #### Check if the number of points of each curve has at least the number of points of minimum_points_num. If not, subdivide to reach at least that number of ponts.
            for i in range(len(curves_duplicate_1.data.splines)):
                sp = curves_duplicate_1.data.splines[i]

                if len(sp.bezier_points) < minimum_points_num:
                    for bp in sp.bezier_points:
                        bp.select_control_point = True

                    if (len(sp.bezier_points) - 1) != 0:
                        subdivide_cuts = int((minimum_points_num - len(sp.bezier_points)) / (len(sp.bezier_points) - 1)) + 1 # Formula to get the number of cuts that will make a curve of N number of points have near to "minimum_points_num" points, when subdividing with this number of cuts.
                    else:
                        subdivide_cuts = 0

                    bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')
                    bpy.ops.curve.subdivide('INVOKE_REGION_WIN', number_cuts = subdivide_cuts)
                    bpy.ops.curve.select_all('INVOKE_REGION_WIN', action='DESELECT')
                    bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')


        bpy.ops.object.duplicate('INVOKE_REGION_WIN')
        curves_duplicate_2 = bpy.context.object
        objects_to_delete.append(curves_duplicate_2)


        #### Duplicate the duplicate and add Shrinkwrap to it, with the grease pencil strokes curve as target.
        bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
        bpy.data.objects[curves_duplicate_2.name].select = True
        bpy.context.scene.objects.active = bpy.data.objects[curves_duplicate_2.name]

        bpy.ops.object.modifier_add('INVOKE_REGION_WIN', type='SHRINKWRAP')
        curves_duplicate_2.modifiers["Shrinkwrap"].wrap_method = "NEAREST_VERTEX"
        curves_duplicate_2.modifiers["Shrinkwrap"].target = GP_strokes_mesh
        bpy.ops.object.modifier_apply('INVOKE_REGION_WIN', apply_as='DATA', modifier='Shrinkwrap')


        #### Get the distance of each vert from its original position to its position with Shrinkwrap.
        nearest_points_coords = {}
        for st_idx in range(len(curves_duplicate_1.data.splines)):
            for bp_idx in range(len(curves_duplicate_1.data.splines[st_idx].bezier_points)):
                bp_1_co = curves_duplicate_1.matrix_world * curves_duplicate_1.data.splines[st_idx].bezier_points[bp_idx].co
                bp_2_co = curves_duplicate_2.matrix_world * curves_duplicate_2.data.splines[st_idx].bezier_points[bp_idx].co

                if bp_idx == 0:
                    shortest_dist = (bp_1_co - bp_2_co).length
                    nearest_points_coords[st_idx] = ("%.4f" % bp_2_co[0], "%.4f" % bp_2_co[1], "%.4f" % bp_2_co[2])

                dist = (bp_1_co - bp_2_co).length

                if dist < shortest_dist:
                    nearest_points_coords[st_idx] = ("%.4f" % bp_2_co[0], "%.4f" % bp_2_co[1], "%.4f" % bp_2_co[2])
                    shortest_dist = dist



        #### Get all coords of GP strokes points, for comparison.
        GP_strokes_coords = []
        for st_idx in range(len(GP_strokes_curve.data.splines)):
            GP_strokes_coords.append([("%.4f" % x if "%.4f" % x != "-0.00" else "0.00", "%.4f" % y if "%.4f" % y != "-0.00" else "0.00", "%.4f" % z if "%.4f" % z != "-0.00" else "0.00") for x, y, z in [bp.co for bp in GP_strokes_curve.data.splines[st_idx].bezier_points]])


        #### Check the point of the GP strokes with the same coords as the nearest points of the curves (with shrinkwrap).
        GP_connection_points = {} # Dictionary with GP stroke index as index, and a list as value. The list has as index the point index of the GP stroke nearest to the spline, and as value the spline index.
        for gp_st_idx in range(len(GP_strokes_coords)):
            GPvert_spline_relationship = {}

            for splines_st_idx in range(len(nearest_points_coords)):
                if nearest_points_coords[splines_st_idx] in GP_strokes_coords[gp_st_idx]:
                    GPvert_spline_relationship[GP_strokes_coords[gp_st_idx].index(nearest_points_coords[splines_st_idx])] = splines_st_idx


            GP_connection_points[gp_st_idx] = GPvert_spline_relationship


        #### Get the splines new order.
        splines_new_order = []
        for i in GP_connection_points:
            dict_keys = sorted(GP_connection_points[i].keys()) # Sort dictionaries by key

            for k in dict_keys:
                splines_new_order.append(GP_connection_points[i][k])



        #### Reorder.

        curve_original_name = self.main_curve.name

        bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
        bpy.data.objects[self.main_curve.name].select = True
        bpy.context.scene.objects.active = bpy.data.objects[self.main_curve.name]

        self.main_curve.name = "SURFSKIO_CRV_ORD"

        bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')
        bpy.ops.curve.select_all('INVOKE_REGION_WIN', action='DESELECT')
        bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')


        for sp_idx in range(len(self.main_curve.data.splines)):
            self.main_curve.data.splines[0].bezier_points[0].select_control_point = True

            bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')
            bpy.ops.curve.separate('INVOKE_REGION_WIN')
            bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')



        #### Get the names of the separated splines objects in the original order.
        splines_unordered = {}
        for o in bpy.data.objects:
            if o.name.find("SURFSKIO_CRV_ORD") != -1:
                spline_order_string = o.name.partition(".")[2]

                if spline_order_string != "" and int(spline_order_string) > 0:
                    spline_order_index = int(spline_order_string) - 1
                    splines_unordered[spline_order_index] = o.name



        #### Join all splines objects in final order.
        for order_idx in splines_new_order:
            bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
            bpy.data.objects[splines_unordered[order_idx]].select = True
            bpy.data.objects["SURFSKIO_CRV_ORD"].select = True
            bpy.context.scene.objects.active = bpy.data.objects["SURFSKIO_CRV_ORD"]

            bpy.ops.object.join('INVOKE_REGION_WIN')


        #### Go back to the original name of the curves object.
        bpy.context.object.name = curve_original_name


        #### Delete all unused objects.
        for o in objects_to_delete:
            bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
            bpy.data.objects[o.name].select = True
            bpy.context.scene.objects.active = bpy.data.objects[o.name]

            bpy.ops.object.delete()


        bpy.ops.object.select_all('INVOKE_REGION_WIN', action='DESELECT')
        bpy.data.objects[curve_original_name].select = True
        bpy.context.scene.objects.active = bpy.data.objects[curve_original_name]

        bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')
        bpy.ops.curve.select_all('INVOKE_REGION_WIN', action='DESELECT')


        bpy.ops.gpencil.active_frame_delete('INVOKE_REGION_WIN')



        return {"FINISHED"}



    def invoke (self, context, event):
        self.main_curve = bpy.context.object


        there_are_GP_strokes = False
        try:
            #### Get the active grease pencil layer.
            strokes_num = len(self.main_curve.grease_pencil.layers.active.active_frame.strokes)

            if strokes_num > 0:
                there_are_GP_strokes = True
        except:
            pass


        if there_are_GP_strokes:
            self.execute(context)
            self.report({'INFO'}, "Splines have been reordered.")
        else:
            self.report({'WARNING'}, "Draw grease pencil strokes to connect splines.")

        return {"FINISHED"}




class CURVE_OT_SURFSK_first_points(bpy.types.Operator):
    bl_idname = "curve.surfsk_first_points"
    bl_label = "Bsurfaces set first points"
    bl_description = "Set the selected points as the first point of each spline."
    bl_options = {'REGISTER', 'UNDO'}



    def execute(self, context):
        splines_to_invert = []

        #### Check non-cyclic splines to invert.
        for i in range(len(self.main_curve.data.splines)):
            b_points = self.main_curve.data.splines[i].bezier_points

            if not i in self.cyclic_splines: # Only for non-cyclic splines
                if b_points[len(b_points) - 1].select_control_point:
                    splines_to_invert.append(i)


        #### Reorder points of cyclic splines, and set all handles to "Automatic".

        # Check first selected point.
        cyclic_splines_new_first_pt = {}
        for i in self.cyclic_splines:
            sp = self.main_curve.data.splines[i]

            for t in range(len(sp.bezier_points)):
                bp = sp.bezier_points[t]
                if bp.select_control_point or bp.select_right_handle or bp.select_left_handle:
                    cyclic_splines_new_first_pt[i] = t
                    break # To take only one if there are more.

        # Reorder.
        for spline_idx in cyclic_splines_new_first_pt:
            sp = self.main_curve.data.splines[spline_idx]

            spline_old_coords = []
            for bp_old in sp.bezier_points:
                coords = (bp_old.co[0], bp_old.co[1], bp_old.co[2])

                left_handle_type = str(bp_old.handle_left_type)
                left_handle_length = float(bp_old.handle_left.length)
                left_handle_xyz = (float(bp_old.handle_left.x), float(bp_old.handle_left.y), float(bp_old.handle_left.z))

                right_handle_type = str(bp_old.handle_right_type)
                right_handle_length = float(bp_old.handle_right.length)
                right_handle_xyz = (float(bp_old.handle_right.x), float(bp_old.handle_right.y), float(bp_old.handle_right.z))

                spline_old_coords.append([coords, left_handle_type, right_handle_type, left_handle_length, right_handle_length, left_handle_xyz, right_handle_xyz])


            for t in range(len(sp.bezier_points)):
                bp = sp.bezier_points

                if t + cyclic_splines_new_first_pt[spline_idx] + 1 <= len(bp) - 1:
                    new_index = t + cyclic_splines_new_first_pt[spline_idx] + 1
                else:
                    new_index = t + cyclic_splines_new_first_pt[spline_idx] + 1 - len(bp)

                bp[t].co = mathutils.Vector(spline_old_coords[new_index][0])

                bp[t].handle_left.length = spline_old_coords[new_index][3]
                bp[t].handle_right.length = spline_old_coords[new_index][4]

                bp[t].handle_left_type = "FREE"
                bp[t].handle_right_type = "FREE"

                bp[t].handle_left.x = spline_old_coords[new_index][5][0]
                bp[t].handle_left.y = spline_old_coords[new_index][5][1]
                bp[t].handle_left.z = spline_old_coords[new_index][5][2]

                bp[t].handle_right.x = spline_old_coords[new_index][6][0]
                bp[t].handle_right.y = spline_old_coords[new_index][6][1]
                bp[t].handle_right.z = spline_old_coords[new_index][6][2]

                bp[t].handle_left_type = spline_old_coords[new_index][1]
                bp[t].handle_right_type = spline_old_coords[new_index][2]



        #### Invert the non-cyclic splines designated above.
        for i in range(len(splines_to_invert)):
            bpy.ops.curve.select_all('INVOKE_REGION_WIN', action='DESELECT')

            bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')
            self.main_curve.data.splines[splines_to_invert[i]].bezier_points[0].select_control_point = True
            bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')

            bpy.ops.curve.switch_direction()

        bpy.ops.curve.select_all('INVOKE_REGION_WIN', action='DESELECT')


        #### Keep selected the first vert of each spline.
        bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')
        for i in range(len(self.main_curve.data.splines)):
            if not self.main_curve.data.splines[i].use_cyclic_u:
                bp = self.main_curve.data.splines[i].bezier_points[0]
            else:
                bp = self.main_curve.data.splines[i].bezier_points[len(self.main_curve.data.splines[i].bezier_points) - 1]

            bp.select_control_point = True
            bp.select_right_handle = True
            bp.select_left_handle = True
        bpy.ops.object.editmode_toggle('INVOKE_REGION_WIN')




        return {'FINISHED'}



    def invoke (self, context, event):
        self.main_curve = bpy.context.object

        # Check if all curves are Bezier, and detect which ones are cyclic.
        self.cyclic_splines = []
        for i in range(len(self.main_curve.data.splines)):
            if self.main_curve.data.splines[i].type != "BEZIER":
                self.report({'WARNING'}, 'All splines must be Bezier type.')

                return {'CANCELLED'}
            else:
                if self.main_curve.data.splines[i].use_cyclic_u:
                    self.cyclic_splines.append(i)



        self.execute(context)
        self.report({'INFO'}, "First points have been set.")

        return {'FINISHED'}




def register():
    bpy.utils.register_class(VIEW3D_PT_tools_SURFSK_mesh)
    bpy.utils.register_class(VIEW3D_PT_tools_SURFSK_curve)
    bpy.utils.register_class(GPENCIL_OT_SURFSK_add_surface)
    bpy.utils.register_class(GPENCIL_OT_SURFSK_edit_strokes)
    bpy.utils.register_class(CURVE_OT_SURFSK_reorder_splines)
    bpy.utils.register_class(CURVE_OT_SURFSK_first_points)



    bpy.types.Scene.SURFSK_cyclic_cross = bpy.props.BoolProperty(
        name="Cyclic Cross",
        description="Make cyclic the face-loops crossing the strokes.",
        default=False)

    bpy.types.Scene.SURFSK_cyclic_follow = bpy.props.BoolProperty(
        name="Cyclic Follow",
        description="Make cyclic the face-loops following the strokes.",
        default=False)

    bpy.types.Scene.SURFSK_keep_strokes = bpy.props.BoolProperty(
        name="Keep strokes",
        description="Keeps the sketched strokes or curves after adding the surface.",
        default=False)

    bpy.types.Scene.SURFSK_automatic_join = bpy.props.BoolProperty(
        name="Automatic join",
        description="Join automatically vertices of either surfaces generated by crosshatching, or from the borders of closed shapes.",
        default=True)

    bpy.types.Scene.SURFSK_loops_on_strokes = bpy.props.BoolProperty(
        name="Loops on strokes",
        description="Make the loops match the paths of the strokes.",
        default=True)

    bpy.types.Scene.SURFSK_precision = bpy.props.IntProperty(
        name="Precision",
        description="Precision level of the surface calculation.",
        default=2,
        min=1,
        max=100)


def unregister():
    bpy.utils.unregister_class(VIEW3D_PT_tools_SURFSK_mesh)
    bpy.utils.unregister_class(VIEW3D_PT_tools_SURFSK_curve)
    bpy.utils.unregister_class(GPENCIL_OT_SURFSK_add_surface)
    bpy.utils.unregister_class(GPENCIL_OT_SURFSK_edit_strokes)
    bpy.utils.unregister_class(CURVE_OT_SURFSK_reorder_splines)
    bpy.utils.unregister_class(CURVE_OT_SURFSK_first_points)

    del bpy.types.Scene.SURFSK_precision
    del bpy.types.Scene.SURFSK_keep_strokes
    del bpy.types.Scene.SURFSK_automatic_join
    del bpy.types.Scene.SURFSK_cyclic_cross
    del bpy.types.Scene.SURFSK_cyclic_follow
    del bpy.types.Scene.SURFSK_loops_on_strokes



if __name__ == "__main__":
    register()