io_export_paper_model.py

            ('SELECTED_TO_ACTIVE', "Selected to Active", "Render all selected surrounding objects as a texture")
        ])
    do_create_stickers: bpy.props.BoolProperty(
        name="Create Tabs", description="Create gluing tabs around the net (useful for paper)",
        default=True)
    do_create_numbers: bpy.props.BoolProperty(
        name="Create Numbers", description="Enumerate edges to make it clear which edges should be sticked together",
        default=True)
    sticker_width: bpy.props.FloatProperty(
        name="Tabs and Text Size", description="Width of gluing tabs and their numbers",
        default=0.005, soft_min=0, soft_max=0.05, step=0.1, subtype="UNSIGNED", unit="LENGTH")
    angle_epsilon: bpy.props.FloatProperty(
        name="Hidden Edge Angle", description="Folds with angle below this limit will not be drawn",
        default=pi/360, min=0, soft_max=pi/4, step=0.01, subtype="ANGLE", unit="ROTATION")
    output_dpi: bpy.props.FloatProperty(
        name="Resolution (DPI)", description="Resolution of images in pixels per inch",
        default=90, min=1, soft_min=30, soft_max=600, subtype="UNSIGNED")
    bake_samples: bpy.props.IntProperty(
        name="Samples", description="Number of samples to render for each pixel",
        default=64, min=1, subtype="UNSIGNED")
    file_format: bpy.props.EnumProperty(
        name="Document Format", description="File format of the exported net",
        default='PDF', items=[
            ('PDF', "PDF", "Adobe Portable Document Format 1.4"),
            ('SVG', "SVG", "W3C Scalable Vector Graphics"),
        ])
    image_packing: bpy.props.EnumProperty(
        name="Image Packing Method", description="Method of attaching baked image(s) to the SVG",
        default='ISLAND_EMBED', items=[
            ('PAGE_LINK', "Single Linked", "Bake one image per page of output and save it separately"),
            ('ISLAND_LINK', "Linked", "Bake images separately for each island and save them in a directory"),
            ('ISLAND_EMBED', "Embedded", "Bake images separately for each island and embed them into the SVG")
        ])
    scale: bpy.props.FloatProperty(
        name="Scale", description="Divisor of all dimensions when exporting",
        default=1, soft_min=1.0, soft_max=100.0, subtype='FACTOR', precision=1)
    do_create_uvmap: bpy.props.BoolProperty(
        name="Create UVMap", description="Create a new UV Map showing the islands and page layout",
        default=False, options={'SKIP_SAVE'})
    ui_expanded_document: bpy.props.BoolProperty(
        name="Show Document Settings Expanded", description="Shows the box 'Document Settings' expanded in user interface",
        default=True, options={'SKIP_SAVE'})
    ui_expanded_style: bpy.props.BoolProperty(
        name="Show Style Settings Expanded", description="Shows the box 'Colors and Style' expanded in user interface",
        default=False, options={'SKIP_SAVE'})
    style: bpy.props.PointerProperty(type=PaperModelStyle)

    unfolder = None

    @classmethod
    def poll(cls, context):
        return context.active_object and context.active_object.type == 'MESH'
    
    def prepare(self, context):
        sce = context.scene
        self.recall_mode = context.object.mode
        bpy.ops.object.mode_set(mode='EDIT')

        self.object = context.active_object
        self.unfolder = Unfolder(self.object)
        cage_size = M.Vector((sce.paper_model.output_size_x, sce.paper_model.output_size_y))
        self.unfolder.prepare(cage_size, scale=sce.unit_settings.scale_length/self.scale, limit_by_page=sce.paper_model.limit_by_page)
        if self.scale == 1:
            self.scale = ceil(self.get_scale_ratio(sce))
    
    def recall(self):
        if self.unfolder:
            del self.unfolder
        bpy.ops.object.mode_set(mode=self.recall_mode)

    def invoke(self, context, event):
        self.scale = context.scene.paper_model.scale
        try:
            self.prepare(context)
        except UnfoldError as error:
            self.report(type={'ERROR_INVALID_INPUT'}, message=error.args[0])
            error.mesh_select()
            self.recall()
            return {'CANCELLED'}
        wm = context.window_manager
        wm.fileselect_add(self)
        return {'RUNNING_MODAL'}

    def execute(self, context):
        if not self.unfolder:
            self.prepare(context)
        self.unfolder.do_create_uvmap = self.do_create_uvmap
        try:
            if self.object.data.paper_island_list:
                self.unfolder.copy_island_names(self.object.data.paper_island_list)
            self.unfolder.save(self.properties)
            self.report({'INFO'}, "Saved a {}-page document".format(len(self.unfolder.mesh.pages)))
            return {'FINISHED'}
        except UnfoldError as error:
            self.report(type={'ERROR_INVALID_INPUT'}, message=error.args[0])
            return {'CANCELLED'}
        finally:
            self.recall()

    def get_scale_ratio(self, sce):
        margin = self.output_margin + self.sticker_width
        if min(self.output_size_x, self.output_size_y) <= 2 * margin:
            return False
        output_inner_size = M.Vector((self.output_size_x - 2*margin, self.output_size_y - 2*margin))
        ratio = self.unfolder.mesh.largest_island_ratio(output_inner_size)
        return ratio * sce.unit_settings.scale_length / self.scale

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

        layout.prop(self.properties, "do_create_uvmap")

        row = layout.row(align=True)
        row.menu("VIEW3D_MT_paper_model_presets", text=bpy.types.VIEW3D_MT_paper_model_presets.bl_label)
        row.operator("export_mesh.paper_model_preset_add", text="", icon='ADD')
        row.operator("export_mesh.paper_model_preset_add", text="", icon='REMOVE').remove_active = True

        layout.prop(self.properties, "scale", text="Scale: 1/")
        scale_ratio = self.get_scale_ratio(context.scene)
        if scale_ratio > 1:
            layout.label(
                text="An island is roughly {:.1f}x bigger than page".format(scale_ratio),
                icon="ERROR")
        elif scale_ratio > 0:
            layout.label(text="Largest island is roughly 1/{:.1f} of page".format(1 / scale_ratio))

        if context.scene.unit_settings.scale_length != 1:
            layout.label(
                text="Unit scale {:.1f} makes page size etc. not display correctly".format(
                    context.scene.unit_settings.scale_length), icon="ERROR")
        box = layout.box()
        row = box.row(align=True)
        row.prop(
            self.properties, "ui_expanded_document", text="",
            icon=('TRIA_DOWN' if self.ui_expanded_document else 'TRIA_RIGHT'), emboss=False)
        row.label(text="Document Settings")

        if self.ui_expanded_document:
            box.prop(self.properties, "file_format", text="Format")
            box.prop(self.properties, "page_size_preset")
            col = box.column(align=True)
            col.active = self.page_size_preset == 'USER'
            col.prop(self.properties, "output_size_x")
            col.prop(self.properties, "output_size_y")
            box.prop(self.properties, "output_margin")
            col = box.column()
            col.prop(self.properties, "do_create_stickers")
            col.prop(self.properties, "do_create_numbers")
            col = box.column()
            col.active = self.do_create_stickers or self.do_create_numbers
            col.prop(self.properties, "sticker_width")
            box.prop(self.properties, "angle_epsilon")

            box.prop(self.properties, "output_type")
            col = box.column()
            col.active = (self.output_type != 'NONE')
            if len(self.object.data.uv_layers) == 8:
                col.label(text="No UV slots left, No Texture is the only option.", icon='ERROR')
            elif context.scene.render.engine != 'CYCLES' and self.output_type != 'NONE':
                col.label(text="Cycles will be used for texture baking.", icon='ERROR')
            row = col.row()
            row.active = self.output_type in ('AMBIENT_OCCLUSION', 'RENDER', 'SELECTED_TO_ACTIVE')
            row.prop(self.properties, "bake_samples")
            col.prop(self.properties, "output_dpi")
            row = col.row()
            row.active = self.file_format == 'SVG'
            row.prop(self.properties, "image_packing", text="Images")

        box = layout.box()
        row = box.row(align=True)
        row.prop(
            self.properties, "ui_expanded_style", text="",
            icon=('TRIA_DOWN' if self.ui_expanded_style else 'TRIA_RIGHT'), emboss=False)
        row.label(text="Colors and Style")

        if self.ui_expanded_style:
            box.prop(self.style, "line_width", text="Default line width")
            col = box.column()
            col.prop(self.style, "outer_color")
            col.prop(self.style, "outer_width", text="Relative width")
            col.prop(self.style, "outer_style", text="Style")
            col = box.column()
            col.active = self.output_type != 'NONE'
            col.prop(self.style, "use_outbg", text="Outer Lines Highlight:")
            sub = col.column()
            sub.active = self.output_type != 'NONE' and self.style.use_outbg
            sub.prop(self.style, "outbg_color", text="")
            sub.prop(self.style, "outbg_width", text="Relative width")
            col = box.column()
            col.prop(self.style, "convex_color")
            col.prop(self.style, "convex_width", text="Relative width")
            col.prop(self.style, "convex_style", text="Style")
            col = box.column()
            col.prop(self.style, "concave_color")
            col.prop(self.style, "concave_width", text="Relative width")
            col.prop(self.style, "concave_style", text="Style")
            col = box.column()
            col.prop(self.style, "freestyle_color")
            col.prop(self.style, "freestyle_width", text="Relative width")
            col.prop(self.style, "freestyle_style", text="Style")
            col = box.column()
            col.active = self.output_type != 'NONE'
            col.prop(self.style, "use_inbg", text="Inner Lines Highlight:")
            sub = col.column()
            sub.active = self.output_type != 'NONE' and self.style.use_inbg
            sub.prop(self.style, "inbg_color", text="")
            sub.prop(self.style, "inbg_width", text="Relative width")
            col = box.column()
            col.active = self.do_create_stickers
            col.prop(self.style, "sticker_fill")
            box.prop(self.style, "text_color")


def menu_func_export(self, context):
    self.layout.operator("export_mesh.paper_model", text="Paper Model (.pdf/.svg)")


def menu_func_unfold(self, context):
    self.layout.operator("mesh.unfold", text="Unfold")


class SelectIsland(bpy.types.Operator):
    """Blender Operator: select all faces of the active island"""

    bl_idname = "mesh.select_paper_island"
    bl_label = "Select Island"
    bl_description = "Select an island of the paper model net"
    
    operation: bpy.props.EnumProperty(
        name="Operation", description="Operation with the current selection",
        default='ADD', items=[
            ('ADD', "Add", "Add to current selection"),
            ('REMOVE', "Remove", "Remove from selection"),
            ('REPLACE', "Replace", "Select only the ")
        ])

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

    def execute(self, context):
        ob = context.active_object
        me = ob.data
        bm = bmesh.from_edit_mesh(me)
        island = me.paper_island_list[me.paper_island_index]
        faces = {face.id for face in island.faces}
        edges = set()
        verts = set()
        if self.operation == 'REPLACE':
            for face in bm.faces:
                selected = face.index in faces
                face.select = selected
                if selected:
                    edges.update(face.edges)
                    verts.update(face.verts)
            for edge in bm.edges:
                edge.select = edge in edges
            for vert in bm.verts:
                vert.select = vert in verts
        else:
            selected = (self.operation == 'ADD')
            for index in faces:
                face = bm.faces[index]
                face.select = selected
                edges.update(face.edges)
                verts.update(face.verts)
            for edge in edges:
                edge.select = any(face.select for face in edge.link_faces)
            for vert in verts:
                vert.select = any(edge.select for edge in vert.link_edges)
        bmesh.update_edit_mesh(me, False, False)
        return {'FINISHED'}


class VIEW3D_MT_paper_model_presets(bpy.types.Menu):
    bl_label = "Paper Model Presets"
    preset_subdir = "export_mesh"
    preset_operator = "script.execute_preset"
    draw = bpy.types.Menu.draw_preset


class AddPresetPaperModel(bl_operators.presets.AddPresetBase, bpy.types.Operator):
    """Add or remove a Paper Model Preset"""
    bl_idname = "export_mesh.paper_model_preset_add"
    bl_label = "Add Paper Model Preset"
    preset_menu = "VIEW3D_MT_paper_model_presets"
    preset_subdir = "export_mesh"
    preset_defines = ["op = bpy.context.active_operator"]

    @property
    def preset_values(self):
        op = bpy.ops.export_mesh.paper_model
        properties = op.get_rna().bl_rna.properties.items()
        blacklist = bpy.types.Operator.bl_rna.properties.keys()
        return [
            "op.{}".format(prop_id) for (prop_id, prop) in properties
            if not (prop.is_hidden or prop.is_skip_save or prop_id in blacklist)]


class VIEW3D_PT_paper_model_tools(bpy.types.Panel):
    bl_space_type = 'VIEW_3D'
    bl_region_type = 'UI'
    bl_category = 'Paper'
    bl_label = "Unfold"

    def draw(self, context):
        layout = self.layout
        sce = context.scene
        obj = context.active_object
        mesh = obj.data if obj and obj.type == 'MESH' else None

        layout.operator("mesh.unfold")

        if context.mode == 'EDIT_MESH':
            row = layout.row(align=True)
            row.operator("mesh.mark_seam", text="Mark Seam").clear = False
            row.operator("mesh.mark_seam", text="Clear Seam").clear = True
        else:
            layout.operator("mesh.clear_all_seams")


class VIEW3D_PT_paper_model_settings(bpy.types.Panel):
    bl_space_type = 'VIEW_3D'
    bl_region_type = 'UI'
    bl_category = 'Paper'
    bl_label = "Export"

    def draw(self, context):
        layout = self.layout
        sce = context.scene
        obj = context.active_object
        mesh = obj.data if obj and obj.type == 'MESH' else None

        layout.operator("export_mesh.paper_model")
        props = sce.paper_model
        layout.prop(props, "scale", text="Model Scale:  1/")

        layout.prop(props, "limit_by_page")
        col = layout.column()
        col.active = props.limit_by_page
        col.prop(props, "page_size_preset")
        sub = col.column(align=True)
        sub.active = props.page_size_preset == 'USER'
        sub.prop(props, "output_size_x")
        sub.prop(props, "output_size_y")


class DATA_PT_paper_model_islands(bpy.types.Panel):
    bl_space_type = 'PROPERTIES'
    bl_region_type = 'WINDOW'
    bl_context = "data"
    bl_label = "Paper Model Islands"
    COMPAT_ENGINES = {'BLENDER_RENDER', 'BLENDER_EEVEE', 'BLENDER_WORKBENCH'}

    def draw(self, context):
        layout = self.layout
        sce = context.scene
        obj = context.active_object
        mesh = obj.data if obj and obj.type == 'MESH' else None

        layout.operator("mesh.unfold", icon='FILE_REFRESH')
        if mesh and mesh.paper_island_list:
            layout.label(
                text="1 island:" if len(mesh.paper_island_list) == 1 else
                "{} islands:".format(len(mesh.paper_island_list)))
            layout.template_list(
                'UI_UL_list', 'paper_model_island_list', mesh,
                'paper_island_list', mesh, 'paper_island_index', rows=1, maxrows=5)
            sub = layout.split(align=True)
            sub.operator("mesh.select_paper_island", text="Select").operation = 'ADD'
            sub.operator("mesh.select_paper_island", text="Deselect").operation = 'REMOVE'
            sub.prop(sce.paper_model, "sync_island", icon='UV_SYNC_SELECT', toggle=True)
            if mesh.paper_island_index >= 0:
                list_item = mesh.paper_island_list[mesh.paper_island_index]
                sub = layout.column(align=True)
                sub.prop(list_item, "auto_label")
                sub.prop(list_item, "label")
                sub.prop(list_item, "auto_abbrev")
                row = sub.row()
                row.active = not list_item.auto_abbrev
                row.prop(list_item, "abbreviation")
        else:
            layout.box().label(text="Not unfolded")


def label_changed(self, context):
    """The label of an island was changed"""
    # accessing properties via [..] to avoid a recursive call after the update
    self["auto_label"] = not self.label or self.label.isspace()
    island_item_changed(self, context)


def island_item_changed(self, context):
    """The labelling of an island was changed"""
    def increment(abbrev, collisions):
        letters = "ABCDEFGHIJKLMNPQRSTUVWXYZ123456789"
        while abbrev in collisions:
            abbrev = abbrev.rstrip(letters[-1])
            abbrev = abbrev[:2] + letters[letters.find(abbrev[-1]) + 1 if len(abbrev) == 3 else 0]
        return abbrev

    # accessing properties via [..] to avoid a recursive call after the update
    island_list = context.active_object.data.paper_island_list
    if self.auto_label:
        self["label"] = ""  # avoid self-conflict
        number = 1
        while any(item.label == "Island {}".format(number) for item in island_list):
            number += 1
        self["label"] = "Island {}".format(number)
    if self.auto_abbrev:
        self["abbreviation"] = ""  # avoid self-conflict
        abbrev = "".join(first_letters(self.label))[:3].upper()
        self["abbreviation"] = increment(abbrev, {item.abbreviation for item in island_list})
    elif len(self.abbreviation) > 3:
        self["abbreviation"] = self.abbreviation[:3]
    self.name = "[{}] {} ({} {})".format(
        self.abbreviation, self.label, len(self.faces), "faces" if len(self.faces) > 1 else "face")


def island_index_changed(self, context):
    """The active island was changed"""
    if context.scene.paper_model.sync_island and SelectIsland.poll(context):
        bpy.ops.mesh.select_paper_island(operation='REPLACE')


class FaceList(bpy.types.PropertyGroup):
    id: bpy.props.IntProperty(name="Face ID")


class IslandList(bpy.types.PropertyGroup):
    faces: bpy.props.CollectionProperty(
        name="Faces", description="Faces belonging to this island", type=FaceList)
    label: bpy.props.StringProperty(
        name="Label", description="Label on this island",
        default="", update=label_changed)
    abbreviation: bpy.props.StringProperty(
        name="Abbreviation", description="Three-letter label to use when there is not enough space",
        default="", update=island_item_changed)
    auto_label: bpy.props.BoolProperty(
        name="Auto Label", description="Generate the label automatically",
        default=True, update=island_item_changed)
    auto_abbrev: bpy.props.BoolProperty(
        name="Auto Abbreviation", description="Generate the abbreviation automatically",
        default=True, update=island_item_changed)


class PaperModelSettings(bpy.types.PropertyGroup):
    sync_island: bpy.props.BoolProperty(
        name="Sync", description="Keep faces of the active island selected",
        default=False, update=island_index_changed)
    limit_by_page: bpy.props.BoolProperty(
        name="Limit Island Size", description="Do not create islands larger than given dimensions",
        default=False, update=page_size_preset_changed)
    page_size_preset: bpy.props.EnumProperty(
        name="Page Size", description="Maximal size of an island",
        default='A4', update=page_size_preset_changed, items=global_paper_sizes)
    output_size_x: bpy.props.FloatProperty(
        name="Width", description="Maximal width of an island",
        default=0.2, soft_min=0.105, soft_max=0.841, subtype="UNSIGNED", unit="LENGTH")
    output_size_y: bpy.props.FloatProperty(
        name="Height", description="Maximal height of an island",
        default=0.29, soft_min=0.148, soft_max=1.189, subtype="UNSIGNED", unit="LENGTH")
    scale: bpy.props.FloatProperty(
        name="Scale", description="Divisor of all dimensions when exporting",
        default=1, soft_min=1.0, soft_max=100.0, subtype='FACTOR', precision=1)


module_classes = (
    Unfold,
    ExportPaperModel,
    ClearAllSeams,
    SelectIsland,
    AddPresetPaperModel,
    FaceList,
    IslandList,
    PaperModelSettings,
    VIEW3D_MT_paper_model_presets,
    DATA_PT_paper_model_islands,
    VIEW3D_PT_paper_model_tools,
    VIEW3D_PT_paper_model_settings,
)


def register():
    for cls in module_classes:
        bpy.utils.register_class(cls)
    bpy.types.Scene.paper_model = bpy.props.PointerProperty(
        name="Paper Model", description="Settings of the Export Paper Model script",
        type=PaperModelSettings, options={'SKIP_SAVE'})
    bpy.types.Mesh.paper_island_list = bpy.props.CollectionProperty(
        name="Island List", type=IslandList)
    bpy.types.Mesh.paper_island_index = bpy.props.IntProperty(
        name="Island List Index",
        default=-1, min=-1, max=100, options={'SKIP_SAVE'}, update=island_index_changed)
    bpy.types.TOPBAR_MT_file_export.append(menu_func_export)
    bpy.types.VIEW3D_MT_edit_mesh.prepend(menu_func_unfold)


def unregister():
    bpy.types.TOPBAR_MT_file_export.remove(menu_func_export)
    bpy.types.VIEW3D_MT_edit_mesh.remove(menu_func_unfold)
    for cls in reversed(module_classes):
        bpy.utils.unregister_class(cls)


if __name__ == "__main__":
    register()