mesh_looptools.py

    return(strokes)


# convert a GP stroke into a list of points which can be stored in cache
def gstretch_true_to_safe_strokes(strokes):
    safe_strokes = []
    for stroke in strokes:
        safe_strokes.append([p.co.copy() for p in stroke.points])

    return(safe_strokes)


# force consistency in GUI, max value can never be lower than min value
def gstretch_update_max(self, context):
    # called from operator settings (after execution)
    if 'conversion_min' in self.keys():
        if self.conversion_min > self.conversion_max:
            self.conversion_max = self.conversion_min
    # called from toolbar
    else:
        lt = context.window_manager.looptools
        if lt.gstretch_conversion_min > lt.gstretch_conversion_max:
            lt.gstretch_conversion_max = lt.gstretch_conversion_min


# force consistency in GUI, min value can never be higher than max value
def gstretch_update_min(self, context):
    # called from operator settings (after execution)
    if 'conversion_max' in self.keys():
        if self.conversion_max < self.conversion_min:
            self.conversion_min = self.conversion_max
    # called from toolbar
    else:
        lt = context.window_manager.looptools
        if lt.gstretch_conversion_max < lt.gstretch_conversion_min:
            lt.gstretch_conversion_min = lt.gstretch_conversion_max


# ########################################
# ##### Relax functions ##################
# ########################################

# create lists with knots and points, all correctly sorted
def relax_calculate_knots(loops):
    all_knots = []
    all_points = []
    for loop, circular in loops:
        knots = [[], []]
        points = [[], []]
        if circular:
            if len(loop) % 2 == 1:  # odd
                extend = [False, True, 0, 1, 0, 1]
            else:  # even
                extend = [True, False, 0, 1, 1, 2]
        else:
            if len(loop) % 2 == 1:  # odd
                extend = [False, False, 0, 1, 1, 2]
            else:  # even
                extend = [False, False, 0, 1, 1, 2]
        for j in range(2):
            if extend[j]:
                loop = [loop[-1]] + loop + [loop[0]]
            for i in range(extend[2 + 2 * j], len(loop), 2):
                knots[j].append(loop[i])
            for i in range(extend[3 + 2 * j], len(loop), 2):
                if loop[i] == loop[-1] and not circular:
                    continue
                if len(points[j]) == 0:
                    points[j].append(loop[i])
                elif loop[i] != points[j][0]:
                    points[j].append(loop[i])
            if circular:
                if knots[j][0] != knots[j][-1]:
                    knots[j].append(knots[j][0])
        if len(points[1]) == 0:
            knots.pop(1)
            points.pop(1)
        for k in knots:
            all_knots.append(k)
        for p in points:
            all_points.append(p)

    return(all_knots, all_points)


# calculate relative positions compared to first knot
def relax_calculate_t(bm_mod, knots, points, regular):
    all_tknots = []
    all_tpoints = []
    for i in range(len(knots)):
        amount = len(knots[i]) + len(points[i])
        mix = []
        for j in range(amount):
            if j % 2 == 0:
                mix.append([True, knots[i][round(j / 2)]])
            elif j == amount - 1:
                mix.append([True, knots[i][-1]])
            else:
                mix.append([False, points[i][int(j / 2)]])
        len_total = 0
        loc_prev = False
        tknots = []
        tpoints = []
        for m in mix:
            loc = mathutils.Vector(bm_mod.verts[m[1]].co[:])
            if not loc_prev:
                loc_prev = loc
            len_total += (loc - loc_prev).length
            if m[0]:
                tknots.append(len_total)
            else:
                tpoints.append(len_total)
            loc_prev = loc
        if regular:
            tpoints = []
            for p in range(len(points[i])):
                tpoints.append((tknots[p] + tknots[p + 1]) / 2)
        all_tknots.append(tknots)
        all_tpoints.append(tpoints)

    return(all_tknots, all_tpoints)


# change the location of the points to their place on the spline
def relax_calculate_verts(bm_mod, interpolation, tknots, knots, tpoints,
points, splines):
    change = []
    move = []
    for i in range(len(knots)):
        for p in points[i]:
            m = tpoints[i][points[i].index(p)]
            if m in tknots[i]:
                n = tknots[i].index(m)
            else:
                t = tknots[i][:]
                t.append(m)
                t.sort()
                n = t.index(m) - 1
            if n > len(splines[i]) - 1:
                n = len(splines[i]) - 1
            elif n < 0:
                n = 0

            if interpolation == 'cubic':
                ax, bx, cx, dx, tx = splines[i][n][0]
                x = ax + bx * (m - tx) + cx * (m - tx) ** 2 + dx * (m - tx) ** 3
                ay, by, cy, dy, ty = splines[i][n][1]
                y = ay + by * (m - ty) + cy * (m - ty) ** 2 + dy * (m - ty) ** 3
                az, bz, cz, dz, tz = splines[i][n][2]
                z = az + bz * (m - tz) + cz * (m - tz) ** 2 + dz * (m - tz) ** 3
                change.append([p, mathutils.Vector([x, y, z])])
            else:  # interpolation == 'linear'
                a, d, t, u = splines[i][n]
                if u == 0:
                    u = 1e-8
                change.append([p, ((m - t) / u) * d + a])
    for c in change:
        move.append([c[0], (bm_mod.verts[c[0]].co + c[1]) / 2])

    return(move)


# ########################################
# ##### Space functions ##################
# ########################################

# calculate relative positions compared to first knot
def space_calculate_t(bm_mod, knots):
    tknots = []
    loc_prev = False
    len_total = 0
    for k in knots:
        loc = mathutils.Vector(bm_mod.verts[k].co[:])
        if not loc_prev:
            loc_prev = loc
        len_total += (loc - loc_prev).length
        tknots.append(len_total)
        loc_prev = loc
    amount = len(knots)
    t_per_segment = len_total / (amount - 1)
    tpoints = [i * t_per_segment for i in range(amount)]

    return(tknots, tpoints)


# change the location of the points to their place on the spline
def space_calculate_verts(bm_mod, interpolation, tknots, tpoints, points,
splines):
    move = []
    for p in points:
        m = tpoints[points.index(p)]
        if m in tknots:
            n = tknots.index(m)
        else:
            t = tknots[:]
            t.append(m)
            t.sort()
            n = t.index(m) - 1
        if n > len(splines) - 1:
            n = len(splines) - 1
        elif n < 0:
            n = 0

        if interpolation == 'cubic':
            ax, bx, cx, dx, tx = splines[n][0]
            x = ax + bx * (m - tx) + cx * (m - tx) ** 2 + dx * (m - tx) ** 3
            ay, by, cy, dy, ty = splines[n][1]
            y = ay + by * (m - ty) + cy * (m - ty) ** 2 + dy * (m - ty) ** 3
            az, bz, cz, dz, tz = splines[n][2]
            z = az + bz * (m - tz) + cz * (m - tz) ** 2 + dz * (m - tz) ** 3
            move.append([p, mathutils.Vector([x, y, z])])
        else:  # interpolation == 'linear'
            a, d, t, u = splines[n]
            move.append([p, ((m - t) / u) * d + a])

    return(move)


# ########################################
# ##### Operators ########################
# ########################################

# bridge operator
class Bridge(Operator):
    bl_idname = 'mesh.looptools_bridge'
    bl_label = "Bridge / Loft"
    bl_description = "Bridge two, or loft several, loops of vertices"
    bl_options = {'REGISTER', 'UNDO'}

    cubic_strength: FloatProperty(
        name="Strength",
        description="Higher strength results in more fluid curves",
        default=1.0,
        soft_min=-3.0,
        soft_max=3.0
        )
    interpolation: EnumProperty(
        name="Interpolation mode",
        items=(('cubic', "Cubic", "Gives curved results"),
            ('linear', "Linear", "Basic, fast, straight interpolation")),
        description="Interpolation mode: algorithm used when creating "
                    "segments",
        default='cubic'
        )
    loft: BoolProperty(
        name="Loft",
        description="Loft multiple loops, instead of considering them as "
                    "a multi-input for bridging",
        default=False
        )
    loft_loop: BoolProperty(
        name="Loop",
        description="Connect the first and the last loop with each other",
        default=False
        )
    min_width: IntProperty(
        name="Minimum width",
        description="Segments with an edge smaller than this are merged "
                    "(compared to base edge)",
        default=0,
        min=0,
        max=100,
        subtype='PERCENTAGE'
        )
    mode: EnumProperty(
        name="Mode",
        items=(('basic', "Basic", "Fast algorithm"),
               ('shortest', "Shortest edge", "Slower algorithm with better vertex matching")),
        description="Algorithm used for bridging",
        default='shortest'
        )
    remove_faces: BoolProperty(
        name="Remove faces",
        description="Remove faces that are internal after bridging",
        default=True
        )
    reverse: BoolProperty(
        name="Reverse",
        description="Manually override the direction in which the loops "
                    "are bridged. Only use if the tool gives the wrong result",
        default=False
        )
    segments: IntProperty(
        name="Segments",
        description="Number of segments used to bridge the gap (0=automatic)",
        default=1,
        min=0,
        soft_max=20
        )
    twist: IntProperty(
        name="Twist",
        description="Twist what vertices are connected to each other",
        default=0
        )

    @classmethod
    def poll(cls, context):
        ob = context.active_object
        return (ob and ob.type == 'MESH' and context.mode == 'EDIT_MESH')

    def draw(self, context):
        layout = self.layout
        # layout.prop(self, "mode") # no cases yet where 'basic' mode is needed

        # top row
        col_top = layout.column(align=True)
        row = col_top.row(align=True)
        col_left = row.column(align=True)
        col_right = row.column(align=True)
        col_right.active = self.segments != 1
        col_left.prop(self, "segments")
        col_right.prop(self, "min_width", text="")
        # bottom row
        bottom_left = col_left.row()
        bottom_left.active = self.segments != 1
        bottom_left.prop(self, "interpolation", text="")
        bottom_right = col_right.row()
        bottom_right.active = self.interpolation == 'cubic'
        bottom_right.prop(self, "cubic_strength")
        # boolean properties
        col_top.prop(self, "remove_faces")
        if self.loft:
            col_top.prop(self, "loft_loop")

        # override properties
        col_top.separator()
        row = layout.row(align=True)
        row.prop(self, "twist")
        row.prop(self, "reverse")

    def invoke(self, context, event):
        # load custom settings
        context.window_manager.looptools.bridge_loft = self.loft
        settings_load(self)
        return self.execute(context)

    def execute(self, context):
        # initialise
        object, bm = initialise()
        edge_faces, edgekey_to_edge, old_selected_faces, smooth = \
            bridge_initialise(bm, self.interpolation)
        settings_write(self)

        # check cache to see if we can save time
        input_method = bridge_input_method(self.loft, self.loft_loop)
        cached, single_loops, loops, derived, mapping = cache_read("Bridge",
            object, bm, input_method, False)
        if not cached:
            # get loops
            loops = bridge_get_input(bm)
            if loops:
                # reorder loops if there are more than 2
                if len(loops) > 2:
                    if self.loft:
                        loops = bridge_sort_loops(bm, loops, self.loft_loop)
                    else:
                        loops = bridge_match_loops(bm, loops)

        # saving cache for faster execution next time
        if not cached:
            cache_write("Bridge", object, bm, input_method, False, False,
                loops, False, False)

        if loops:
            # calculate new geometry
            vertices = []
            faces = []
            max_vert_index = len(bm.verts) - 1
            for i in range(1, len(loops)):
                if not self.loft and i % 2 == 0:
                    continue
                lines = bridge_calculate_lines(bm, loops[i - 1:i + 1],
                    self.mode, self.twist, self.reverse)
                vertex_normals = bridge_calculate_virtual_vertex_normals(bm,
                    lines, loops[i - 1:i + 1], edge_faces, edgekey_to_edge)
                segments = bridge_calculate_segments(bm, lines,
                    loops[i - 1:i + 1], self.segments)
                new_verts, new_faces, max_vert_index = \
                    bridge_calculate_geometry(
                        bm, lines, vertex_normals,
                        segments, self.interpolation, self.cubic_strength,
                        self.min_width, max_vert_index
                        )
                if new_verts:
                    vertices += new_verts
                if new_faces:
                    faces += new_faces
            # make sure faces in loops that aren't used, aren't removed
            if self.remove_faces and old_selected_faces:
                bridge_save_unused_faces(bm, old_selected_faces, loops)
            # create vertices
            if vertices:
                bridge_create_vertices(bm, vertices)
            # create faces
            if faces:
                new_faces = bridge_create_faces(object, bm, faces, self.twist)
                old_selected_faces = [
                    i for i, face in enumerate(bm.faces) if face.index in old_selected_faces
                    ]  # updating list
                bridge_select_new_faces(new_faces, smooth)
            # edge-data could have changed, can't use cache next run
            if faces and not vertices:
                cache_delete("Bridge")
            # delete internal faces
            if self.remove_faces and old_selected_faces:
                bridge_remove_internal_faces(bm, old_selected_faces)
            # make sure normals are facing outside
            bmesh.update_edit_mesh(object.data, loop_triangles=False,
                destructive=True)
            bpy.ops.mesh.normals_make_consistent()

        # cleaning up
        terminate()

        return{'FINISHED'}


# circle operator
class Circle(Operator):
    bl_idname = "mesh.looptools_circle"
    bl_label = "Circle"
    bl_description = "Move selected vertices into a circle shape"
    bl_options = {'REGISTER', 'UNDO'}

    custom_radius: BoolProperty(
        name="Radius",
        description="Force a custom radius",
        default=False
        )
    fit: EnumProperty(
        name="Method",
        items=(("best", "Best fit", "Non-linear least squares"),
               ("inside", "Fit inside", "Only move vertices towards the center")),
        description="Method used for fitting a circle to the vertices",
        default='best'
        )
    flatten: BoolProperty(
        name="Flatten",
        description="Flatten the circle, instead of projecting it on the mesh",
        default=True
        )
    influence: FloatProperty(
        name="Influence",
        description="Force of the tool",
        default=100.0,
        min=0.0,
        max=100.0,
        precision=1,
        subtype='PERCENTAGE'
        )
    lock_x: BoolProperty(
        name="Lock X",
        description="Lock editing of the x-coordinate",
        default=False
        )
    lock_y: BoolProperty(
        name="Lock Y",
        description="Lock editing of the y-coordinate",
        default=False
        )
    lock_z: BoolProperty(name="Lock Z",
        description="Lock editing of the z-coordinate",
        default=False
        )
    radius: FloatProperty(
        name="Radius",
        description="Custom radius for circle",
        default=1.0,
        min=0.0,
        soft_max=1000.0
        )
    regular: BoolProperty(
        name="Regular",
        description="Distribute vertices at constant distances along the circle",
        default=True
        )

    @classmethod
    def poll(cls, context):
        ob = context.active_object
        return(ob and ob.type == 'MESH' and context.mode == 'EDIT_MESH')

    def draw(self, context):
        layout = self.layout
        col = layout.column()

        col.prop(self, "fit")
        col.separator()

        col.prop(self, "flatten")
        row = col.row(align=True)
        row.prop(self, "custom_radius")
        row_right = row.row(align=True)
        row_right.active = self.custom_radius
        row_right.prop(self, "radius", text="")
        col.prop(self, "regular")
        col.separator()

        col_move = col.column(align=True)
        row = col_move.row(align=True)
        if self.lock_x:
            row.prop(self, "lock_x", text="X", icon='LOCKED')
        else:
            row.prop(self, "lock_x", text="X", icon='UNLOCKED')
        if self.lock_y:
            row.prop(self, "lock_y", text="Y", icon='LOCKED')
        else:
            row.prop(self, "lock_y", text="Y", icon='UNLOCKED')
        if self.lock_z:
            row.prop(self, "lock_z", text="Z", icon='LOCKED')
        else:
            row.prop(self, "lock_z", text="Z", icon='UNLOCKED')
        col_move.prop(self, "influence")

    def invoke(self, context, event):
        # load custom settings
        settings_load(self)
        return self.execute(context)

    def execute(self, context):
        # initialise
        object, bm = initialise()
        settings_write(self)
        # check cache to see if we can save time
        cached, single_loops, loops, derived, mapping = cache_read("Circle",
            object, bm, False, False)
        if cached:
            derived, bm_mod = get_derived_bmesh(object, bm, False)
        else:
            # find loops
            derived, bm_mod, single_vertices, single_loops, loops = \
                circle_get_input(object, bm)
            mapping = get_mapping(derived, bm, bm_mod, single_vertices,
                False, loops)
            single_loops, loops = circle_check_loops(single_loops, loops,
                mapping, bm_mod)

        # saving cache for faster execution next time
        if not cached:
            cache_write("Circle", object, bm, False, False, single_loops,
                loops, derived, mapping)

        move = []
        for i, loop in enumerate(loops):
            # best fitting flat plane
            com, normal = calculate_plane(bm_mod, loop)
            # if circular, shift loop so we get a good starting vertex
            if loop[1]:
                loop = circle_shift_loop(bm_mod, loop, com)
            # flatten vertices on plane
            locs_2d, p, q = circle_3d_to_2d(bm_mod, loop, com, normal)
            # calculate circle
            if self.fit == 'best':
                x0, y0, r = circle_calculate_best_fit(locs_2d)
            else:  # self.fit == 'inside'
                x0, y0, r = circle_calculate_min_fit(locs_2d)
            # radius override
            if self.custom_radius:
                r = self.radius / p.length
            # calculate positions on circle
            if self.regular:
                new_locs_2d = circle_project_regular(locs_2d[:], x0, y0, r)
            else:
                new_locs_2d = circle_project_non_regular(locs_2d[:], x0, y0, r)
            # take influence into account
            locs_2d = circle_influence_locs(locs_2d, new_locs_2d,
                self.influence)
            # calculate 3d positions of the created 2d input
            move.append(circle_calculate_verts(self.flatten, bm_mod,
                locs_2d, com, p, q, normal))
            # flatten single input vertices on plane defined by loop
            if self.flatten and single_loops:
                move.append(circle_flatten_singles(bm_mod, com, p, q,
                    normal, single_loops[i]))

        # move vertices to new locations
        if self.lock_x or self.lock_y or self.lock_z:
            lock = [self.lock_x, self.lock_y, self.lock_z]
        else:
            lock = False
        move_verts(object, bm, mapping, move, lock, -1)

        # cleaning up
        if derived:
            bm_mod.free()
        terminate()

        return{'FINISHED'}


# curve operator
class Curve(Operator):
    bl_idname = "mesh.looptools_curve"
    bl_label = "Curve"
    bl_description = "Turn a loop into a smooth curve"
    bl_options = {'REGISTER', 'UNDO'}

    boundaries: BoolProperty(
        name="Boundaries",
        description="Limit the tool to work within the boundaries of the selected vertices",
        default=False
        )
    influence: FloatProperty(
        name="Influence",
        description="Force of the tool",
        default=100.0,
        min=0.0,
        max=100.0,
        precision=1,
        subtype='PERCENTAGE'
        )
    interpolation: EnumProperty(
        name="Interpolation",
        items=(("cubic", "Cubic", "Natural cubic spline, smooth results"),
              ("linear", "Linear", "Simple and fast linear algorithm")),
        description="Algorithm used for interpolation",
        default='cubic'
        )
    lock_x: BoolProperty(
        name="Lock X",
        description="Lock editing of the x-coordinate",
        default=False
        )
    lock_y: BoolProperty(
        name="Lock Y",
        description="Lock editing of the y-coordinate",
        default=False
        )
    lock_z: BoolProperty(
        name="Lock Z",
        description="Lock editing of the z-coordinate",
        default=False
        )
    regular: BoolProperty(
        name="Regular",
        description="Distribute vertices at constant distances along the curve",
        default=True
        )
    restriction: EnumProperty(
        name="Restriction",
        items=(("none", "None", "No restrictions on vertex movement"),
              ("extrude", "Extrude only", "Only allow extrusions (no indentations)"),
              ("indent", "Indent only", "Only allow indentation (no extrusions)")),
        description="Restrictions on how the vertices can be moved",
        default='none'
        )

    @classmethod
    def poll(cls, context):
        ob = context.active_object
        return(ob and ob.type == 'MESH' and context.mode == 'EDIT_MESH')

    def draw(self, context):
        layout = self.layout
        col = layout.column()

        col.prop(self, "interpolation")
        col.prop(self, "restriction")
        col.prop(self, "boundaries")
        col.prop(self, "regular")
        col.separator()

        col_move = col.column(align=True)
        row = col_move.row(align=True)
        if self.lock_x:
            row.prop(self, "lock_x", text="X", icon='LOCKED')
        else:
            row.prop(self, "lock_x", text="X", icon='UNLOCKED')
        if self.lock_y:
            row.prop(self, "lock_y", text="Y", icon='LOCKED')
        else:
            row.prop(self, "lock_y", text="Y", icon='UNLOCKED')
        if self.lock_z:
            row.prop(self, "lock_z", text="Z", icon='LOCKED')
        else:
            row.prop(self, "lock_z", text="Z", icon='UNLOCKED')
        col_move.prop(self, "influence")

    def invoke(self, context, event):
        # load custom settings
        settings_load(self)
        return self.execute(context)

    def execute(self, context):
        # initialise
        object, bm = initialise()
        settings_write(self)
        # check cache to see if we can save time
        cached, single_loops, loops, derived, mapping = cache_read("Curve",
            object, bm, False, self.boundaries)
        if cached:
            derived, bm_mod = get_derived_bmesh(object, bm, False)
        else:
            # find loops
            derived, bm_mod, loops = curve_get_input(object, bm, self.boundaries)
            mapping = get_mapping(derived, bm, bm_mod, False, True, loops)
            loops = check_loops(loops, mapping, bm_mod)
        verts_selected = [
            v.index for v in bm_mod.verts if v.select and not v.hide
            ]

        # saving cache for faster execution next time
        if not cached:
            cache_write("Curve", object, bm, False, self.boundaries, False,
                loops, derived, mapping)

        move = []
        for loop in loops:
            knots, points = curve_calculate_knots(loop, verts_selected)
            pknots = curve_project_knots(bm_mod, verts_selected, knots,
                points, loop[1])
            tknots, tpoints = curve_calculate_t(bm_mod, knots, points,
                pknots, self.regular, loop[1])
            splines = calculate_splines(self.interpolation, bm_mod,
                tknots, knots)
            move.append(curve_calculate_vertices(bm_mod, knots, tknots,
                points, tpoints, splines, self.interpolation,
                self.restriction))

        # move vertices to new locations
        if self.lock_x or self.lock_y or self.lock_z:
            lock = [self.lock_x, self.lock_y, self.lock_z]
        else:
            lock = False
        move_verts(object, bm, mapping, move, lock, self.influence)

        # cleaning up
        if derived:
            bm_mod.free()
        terminate()

        return{'FINISHED'}


# flatten operator
class Flatten(Operator):
    bl_idname = "mesh.looptools_flatten"
    bl_label = "Flatten"
    bl_description = "Flatten vertices on a best-fitting plane"
    bl_options = {'REGISTER', 'UNDO'}

    influence: FloatProperty(
        name="Influence",
        description="Force of the tool",
        default=100.0,
        min=0.0,
        max=100.0,
        precision=1,
        subtype='PERCENTAGE'
        )
    lock_x: BoolProperty(
        name="Lock X",
        description="Lock editing of the x-coordinate",
        default=False
        )
    lock_y: BoolProperty(
        name="Lock Y",
        description="Lock editing of the y-coordinate",
        default=False
        )
    lock_z: BoolProperty(name="Lock Z",
        description="Lock editing of the z-coordinate",
        default=False
        )
    plane: EnumProperty(
        name="Plane",
        items=(("best_fit", "Best fit", "Calculate a best fitting plane"),
              ("normal", "Normal", "Derive plane from averaging vertex normals"),
              ("view", "View", "Flatten on a plane perpendicular to the viewing angle")),
        description="Plane on which vertices are flattened",
        default='best_fit'
        )
    restriction: EnumProperty(
        name="Restriction",
        items=(("none", "None", "No restrictions on vertex movement"),
               ("bounding_box", "Bounding box", "Vertices are restricted to "
               "movement inside the bounding box of the selection")),
        description="Restrictions on how the vertices can be moved",
        default='none'
        )

    @classmethod
    def poll(cls, context):
        ob = context.active_object
        return(ob and ob.type == 'MESH' and context.mode == 'EDIT_MESH')

    def draw(self, context):
        layout = self.layout
        col = layout.column()

        col.prop(self, "plane")
        # col.prop(self, "restriction")
        col.separator()

        col_move = col.column(align=True)
        row = col_move.row(align=True)
        if self.lock_x:
            row.prop(self, "lock_x", text="X", icon='LOCKED')
        else:
            row.prop(self, "lock_x", text="X", icon='UNLOCKED')
        if self.lock_y:
            row.prop(self, "lock_y", text="Y", icon='LOCKED')
        else:
            row.prop(self, "lock_y", text="Y", icon='UNLOCKED')
        if self.lock_z:
            row.prop(self, "lock_z", text="Z", icon='LOCKED')
        else:
            row.prop(self, "lock_z", text="Z", icon='UNLOCKED')
        col_move.prop(self, "influence")

    def invoke(self, context, event):
        # load custom settings
        settings_load(self)
        return self.execute(context)

    def execute(self, context):
        # initialise
        object, bm = initialise()
        settings_write(self)
        # check cache to see if we can save time
        cached, single_loops, loops, derived, mapping = cache_read("Flatten",
            object, bm, False, False)
        if not cached:
            # order input into virtual loops
            loops = flatten_get_input(bm)
            loops = check_loops(loops, mapping, bm)

        # saving cache for faster execution next time
        if not cached:
            cache_write("Flatten", object, bm, False, False, False, loops,
                False, False)

        move = []
        for loop in loops:
            # calculate plane and position of vertices on them
            com, normal = calculate_plane(bm, loop, method=self.plane,
                object=object)
            to_move = flatten_project(bm, loop, com, normal)
            if self.restriction == 'none':
                move.append(to_move)
            else:
                move.append(to_move)

        # move vertices to new locations
        if self.lock_x or self.lock_y or self.lock_z:
            lock = [self.lock_x, self.lock_y, self.lock_z]
        else:
            lock = False
        move_verts(object, bm, False, move, lock, self.influence)

        # cleaning up
        terminate()

        return{'FINISHED'}


# Annotation operator
class RemoveAnnotation(Operator):
    bl_idname = "remove.annotation"
    bl_label = "Remove Annotation"
    bl_description = "Remove all Annotation Strokes"
    bl_options = {'REGISTER', 'UNDO'}

    def execute(self, context):

        try:
            bpy.data.grease_pencils[0].layers.active.clear()
        except:
            self.report({'INFO'}, "No Annotation data to Unlink")
            return {'CANCELLED'}

        return{'FINISHED'}

# GPencil operator
class RemoveGPencil(Operator):
    bl_idname = "remove.gp"
    bl_label = "Remove GPencil"
    bl_description = "Remove all GPencil Strokes"
    bl_options = {'REGISTER', 'UNDO'}

    def execute(self, context):

        try:
            looptools =  context.window_manager.looptools
            looptools.gstretch_guide.data.layers.data.clear()
            looptools.gstretch_guide.data.update_tag()
        except:
            self.report({'INFO'}, "No GPencil data to Unlink")
            return {'CANCELLED'}

        return{'FINISHED'}


class GStretch(Operator):
    bl_idname = "mesh.looptools_gstretch"
    bl_label = "Gstretch"
    bl_description = "Stretch selected vertices to active stroke"
    bl_options = {'REGISTER', 'UNDO'}

    conversion: EnumProperty(
        name="Conversion",
        items=(("distance", "Distance", "Set the distance between vertices "
                "of the converted  stroke"),
               ("limit_vertices", "Limit vertices", "Set the minimum and maximum "
                "number of vertices that converted strokes will have"),
               ("vertices", "Exact vertices", "Set the exact number of vertices "
                "that converted strokes will have. Short strokes "
                "with few points may contain less vertices than this number."),
               ("none", "No simplification", "Convert each point "
                "to a vertex")),
        description="If strokes are converted to geometry, "
                    "use this simplification method",
        default='limit_vertices'
        )
    conversion_distance: FloatProperty(
        name="Distance",
        description="Absolute distance between vertices along the converted "
                    " stroke",
        default=0.1,
        min=0.000001,
        soft_min=0.01,
        soft_max=100
        )
    conversion_max: IntProperty(
        name="Max Vertices",
        description="Maximum number of vertices strokes will "
                    "have, when they are converted to geomtery",
        default=32,
        min=3,
        soft_max=500,
        update=gstretch_update_min
        )
    conversion_min: IntProperty(
        name="Min Vertices",
        description="Minimum number of vertices strokes will "
                    "have, when they are converted to geomtery",
        default=8,
        min=3,
        soft_max=500,
        update=gstretch_update_max
        )
    conversion_vertices: IntProperty(
        name="Vertices",
        description="Number of vertices strokes will "
                    "have, when they are converted to geometry. If strokes have less "
                    "points than required, the 'Spread evenly' method is used",
        default=32,
        min=3,
        soft_max=500
        )
    delete_strokes: BoolProperty(
        name="Delete strokes",
        description="Remove strokes if they have been used."
                    "WARNING: DOES NOT SUPPORT UNDO",
        default=False
        )
    influence: FloatProperty(
        name="Influence",
        description="Force of the tool",
        default=100.0,
        min=0.0,
        max=100.0,
        precision=1,
        subtype='PERCENTAGE'
        )
    lock_x: BoolProperty(
        name="Lock X",
        description="Lock editing of the x-coordinate",
        default=False
        )
    lock_y: BoolProperty(
        name="Lock Y",
        description="Lock editing of the y-coordinate",
        default=False
        )
    lock_z: BoolProperty(
        name="Lock Z",
        description="Lock editing of the z-coordinate",
        default=False
        )
    method: EnumProperty(
        name="Method",
        items=(("project", "Project", "Project vertices onto the stroke, "
                 "using vertex normals and connected edges"),
                ("irregular", "Spread", "Distribute vertices along the full "
                "stroke, retaining relative distances between the vertices"),
                ("regular", "Spread evenly", "Distribute vertices at regular "
                "distances along the full stroke")),
        description="Method of distributing the vertices over the "
                    "stroke",
        default='regular'
        )

    @classmethod
    def poll(cls, context):
        ob = context.active_object
        return(ob and ob.type == 'MESH' and context.mode == 'EDIT_MESH')

    def draw(self, context):
        looptools =  context.window_manager.looptools