manyfold3d/mittsu-3mf

require "builder"
require "zip/filesystem"

module Mittsu
  class ThreeMFExporter
    def initialize(options = {})
    end

    def export(object, filename)
      Zip::OutputStream.open(filename) do |zip|
        # OPC content types file
        store(zip, "[Content_Types].xml", content_types_file)
        # Add models
        models = [object]
        model_names = models.map do |model|
          # Set a model name if there isn't one
          model.name ||= SecureRandom.uuid
          # Store model
          name = filesystem_safe_name(model)
          store(zip, "3D/#{name}.model", model_file(model))
          # Remember the name for later
          name
        end
        # Add OPC rels file with list of contained models
        store(zip, "_rels/.rels", rels_file(model_names))
      end
      true
    end

    # Parse is here for consistency with THREE.js's weird naming of exporter methods
    alias_method :parse, :export

    private

    def filesystem_safe_name(model)
      model.name.delete("/\\?*:|\"<>")
    end

    def store(zip, filename, data)
      zip.put_next_entry(filename)
      zip.write(data)
    end

    def build &block
      xml = Builder::XmlMarkup.new
      xml.instruct! :xml, encoding: "UTF-8"
      yield xml
      xml.target!
    end

    def content_types_file
      build do |xml|
        xml.Types xmlns: "http://schemas.openxmlformats.org/package/2006/content-types" do
          xml.Default Extension: "rels", ContentType: "application/vnd.openxmlformats-package.relationships+xml"
          xml.Default Extension: "model", ContentType: "application/vnd.ms-package.3dmanufacturing-3dmodel+xml"
        end
      end
    end

    def rels_file(models)
      build do |xml|
        xml.Relationships xmlns: "http://schemas.openxmlformats.org/package/2006/relationships" do
          models.each do |name|
            xml.Relationship Target: "/3D/#{name}.model", Id: name, ContentType: "http://schemas.microsoft.com/3dmanufacturing/2013/01/3dmodel"
          end
        end
      end
    end

    def model_file(object)
      build do |xml|
        xml.model unit: "millimeter", "xml:lang": "en-US", xmlns: "http://schemas.microsoft.com/3dmanufacturing/core/2015/02" do
          object_ids = []
          xml.resources do
            object.traverse do |x|
              if x.is_a? Mesh
                object_ids << build_object(xml, x)
              end
            end
          end
          xml.build do
            object_ids.each do |id|
              xml.item objectid: id
            end
          end
        end
      end
    end

    def build_object(xml, object)
      uuid = SecureRandom.uuid
      xml.object id: uuid, type: "model" do
        build_mesh_element(xml, object.geometry)
      end
      uuid
    end

    def build_mesh_element(xml, geometry)
      xml.mesh do
        xml.vertices do
          geometry.vertices.each do |vertex|
            xml.vertex x: vertex.x, y: vertex.y, z: vertex.z
          end
        end
        xml.triangles do
          geometry.faces.each do |face|
            xml.triangle v1: face.a, v2: face.b, v3: face.c
          end
        end
      end
    end
  end
end