Check for non-manifold mesh errors

Gemfile

@@ -97,7 +97,7 @@ gem "acts_as_favoritor", "~> 6.0"
 
 gem "sqlite3_ar_regexp", "~> 2.2"
 
-gem "mittsu", github: "danini-the-panini/mittsu", ref: "7f44c46"
+gem "mittsu", github: "manyfold3d/mittsu", ref: "manyfold"
 
 gem "view_component", "~> 3.11"
 

Gemfile.lock

@@ -8,14 +8,16 @@ GIT
       railties (>= 6.0)
 
 GIT
-  remote: https://github.com/danini-the-panini/mittsu.git
-  revision: 7f44c468f9d6d8b5548ca933dea2d1a873ac496d
-  ref: 7f44c46
+  remote: https://github.com/manyfold3d/mittsu.git
+  revision: cd538af53493c09b0a2497c51569be6c1c6fc1d6
+  ref: manyfold
   specs:
     mittsu (0.4.0)
+      builder
       chunky_png
       ffi
       opengl-bindings
+      rubyzip
 
 GEM
   remote: https://rubygems.org/
@@ -164,7 +166,6 @@ GEM
     faker (3.3.0)
       i18n (>= 1.8.11, < 2)
     ffi (1.16.3)
-    ffi (1.16.3-x64-mingw-ucrt)
     ffi-libarchive (1.1.14)
       ffi (~> 1.0)
     flipper (1.2.2)
@@ -298,7 +299,7 @@ GEM
     notiffany (0.1.3)
       nenv (~> 0.1)
       shellany (~> 0.0)
-    opengl-bindings (1.6.13)
+    opengl-bindings (1.6.14)
     orm_adapter (0.5.0)
     parallel (1.24.0)
     parser (3.3.0.5)
@@ -442,6 +443,7 @@ GEM
       rubocop (~> 1.40)
     ruby-progressbar (1.13.0)
     ruby2_keywords (0.0.5)
+    rubyzip (2.3.2)
     sass-rails (6.0.0)
       sassc-rails (~> 2.1, >= 2.1.1)
     sassc (2.4.0)

app/jobs/scan/analyse_model_file_job.rb

@@ -1,19 +1,23 @@
 require "string/similarity"
 
 class Scan::AnalyseModelFileJob < ApplicationJob
-  queue_as :scan
+  queue_as :analysis
 
   def perform(file_id)
     file = ModelFile.find(file_id)
     return if file.nil?
     # Don't run analysis if the file is missing
     # The Problem is raised elsewhere.
     return if !File.exist?(file.pathname)
-    # Update stored file metadata if not set
-    file.update!(
-      digest: file.digest || file.calculate_digest,
-      size: file.size || File.size(file.pathname)
-    )
+    # If the file is modified, or we're lacking metadata
+    if File.mtime(file.pathname) > file.updated_at || file.digest.nil? || file.size.nil?
+      file.digest = file.calculate_digest
+      file.size = File.size(file.pathname)
+      # If the digest has changed, queue up detailed geometric mesh analysis
+      Scan::GeometricAnalysisJob.perform_later(file_id) if file.digest_changed?
+      # Store updated file metadata
+      file.save!
+    end
     # Match supported files
     match_with_supported_file(file)
     # Detect inefficient file formats

app/jobs/scan/geometric_analysis_job.rb

@@ -0,0 +1,28 @@
+class Scan::GeometricAnalysisJob < ApplicationJob
+  queue_as :analysis
+
+  def perform(file_id)
+    # Get model
+    file = ModelFile.find(file_id)
+    return if file.nil?
+    # Get mesh
+    mesh = file.mesh
+    if mesh
+      # Check for manifold mesh
+      manifold = mesh.manifold?
+      Problem.create_or_clear(
+        file,
+        :non_manifold,
+        !manifold
+      )
+      # If the mesh is manifold, we can check if it's inside out
+      if manifold
+        Problem.create_or_clear(
+          file,
+          :inside_out,
+          !mesh.solid?
+        )
+      end
+    end
+  end
+end

app/lib/mesh_analysis.rb

@@ -0,0 +1,66 @@
+module MeshAnalysis
+  def solid?
+    # Shortcut if there is nothing here
+    return true if geometry.nil? && children.empty?
+    # Recurse children to see if they are solid
+    children_are_solid = children.map { |x| x.solid? }.all?
+    solid = true
+    if geometry
+      # Make sure material is double sided
+      prev_side = material.side
+      material.side = Mittsu::DoubleSide
+      # Make a raycaster from a vertex and the face normal
+      face = geometry.faces.first
+      r = Mittsu::Raycaster.new(geometry.vertices[face.b], face.normal, 1e-9)
+      intersections = r.intersect_object(self, true)
+      # Restore material
+      material.side = prev_side
+      # We want an even number of intersections
+      solid = (intersections.length % 2 == 0)
+    end
+    solid && children_are_solid
+  end
+
+  def manifold?
+    # Shortcut if there is nothing here
+    return true if geometry.nil? && children.empty?
+    # Recurse children to see if they are manifold
+    children_are_manifold = children.map { |x| x.manifold? }.all?
+    # Detect manifold geometry in this object
+    edges = {}
+    # For each face, record its edges in the edge hash
+    geometry&.faces&.each do |face|
+      update_edge_hash face.a, face.b, edges
+      update_edge_hash face.b, face.c, edges
+      update_edge_hash face.c, face.a, edges
+    end
+    # If there's anything left in the edge hash, then either
+    # we have holes, or we have badly oriented faces
+    edges.empty? && children_are_manifold
+  end
+
+  private
+
+  # Updates edge hash with the passed vertex indexes
+  # First, the reverse edge is searched for in the hash
+  # If found, it's removed as we've got a match
+  # If not, we record this edge in the hash
+  def update_edge_hash(v1, v2, edges)
+    return if edges.delete "#{v2}->#{v1}"
+    edges["#{v1}->#{v2}"] = true
+  end
+end
+
+module Mittsu
+  class Object3D
+    include MeshAnalysis
+  end
+
+  class Face3
+    def flip!
+      tmp = @a
+      @a = @c
+      @c = tmp
+    end
+  end
+end

app/models/model_file.rb

@@ -102,6 +102,11 @@ def self.ransackable_associations(_auth_object = nil)
     ["favorited", "model", "problems"]
   end
 
+  def mesh
+    loader&.new&.load(pathname)
+  end
+  memoize :mesh
+
   private
 
   def presupported_files_cannot_have_presupported_version
@@ -116,13 +121,10 @@ def presupported_version_is_presupported
     end
   end
 
-  def mesh
-    loader&.new&.load(pathname)
-  end
-  memoize :mesh
-
   def loader
     case extension
+    when "stl"
+      Mittsu::STLLoader
     when "obj"
       Mittsu::OBJLoader
     end

app/models/problem.rb

@@ -18,7 +18,9 @@ class Problem < ApplicationRecord
     :inefficient,
     :duplicate,
     :no_image,
-    :no_3d_model
+    :no_3d_model,
+    :non_manifold,
+    :inside_out
   ]
   enum :category, CATEGORIES
 
@@ -36,7 +38,9 @@ class Problem < ApplicationRecord
     inefficient: :info,
     duplicate: :warning,
     no_image: :silent,
-    no_3d_model: :silent
+    no_3d_model: :silent,
+    non_manifold: :warning,
+    inside_out: :warning
   }
 
   def self.create_or_clear(problematic, cat, present, options = {})

app/views/model_files/_problem.html.erb

@@ -1,7 +1,7 @@
 <%= card(problem_severity(problem), t("problems.model_file.%{cat}.title" % {cat: problem.category})) do %>
   <%= t(("problems.model_file.%{cat}.description" % {cat: problem.category}), note: problem.note) %>
 
-  <% unless @duplicates.empty? %>
+  <% if problem.category == "duplicate" && !@duplicates.empty? %>
     <ul>
       <% @duplicates.each do |file| %>
         <li><%= link_to "#{file.model.name}/#{file.filename}", [file.model.library, file.model, file] %></li>

app/views/problems/model_file/_inside_out.html.erb

@@ -0,0 +1,4 @@
+<td><%= icon("files", t(".title")) %></td>
+<td><%= link_to problem.problematic.name, [problem.problematic.model.library, problem.problematic.model, problem.problematic] %></td>
+<td><%= t ".title" %></td>
+<td><%= link_to "Open", [problem.problematic.model.library, problem.problematic.model, problem.problematic], class: "btn btn-primary" %></td>

app/views/problems/model_file/_non_manifold.html.erb

@@ -0,0 +1,4 @@
+<td><%= icon("files", t(".title")) %></td>
+<td><%= link_to problem.problematic.name, [problem.problematic.model.library, problem.problematic.model, problem.problematic] %></td>
+<td><%= t ".title" %></td>
+<td><%= link_to "Open", [problem.problematic.model.library, problem.problematic.model, problem.problematic], class: "btn btn-primary" %></td>

config/initializers/delayed_job_extensions.rb

@@ -3,3 +3,9 @@ def self.ransackable_attributes(auth_object = nil)
     ["attempts", "created_at", "failed_at", "handler", "id", "last_error", "locked_at", "locked_by", "priority", "queue", "run_at", "updated_at"]
   end
 end
+
+Delayed::Worker.queue_attributes = {
+  default: {priority: 0},
+  scan: {priority: 0},
+  analysis: {priority: 10}
+}

config/initializers/mittsu.rb

@@ -0,0 +1,2 @@
+# Load mittsu extensions
+require Rails.root.join("app/lib/mesh_analysis")

config/locales/problems/en.yml

@@ -9,6 +9,8 @@ en:
       nesting: Model contains other models
       no_3d_model: Model has no 3D files
       no_image: Model has no image files
+      non_manifold: Mesh is non-manifold
+      inside_out: Mesh is inside-out
     filters:
       apply_filters: Apply
       clear_filters: Clear
@@ -48,6 +50,12 @@ en:
       missing:
         description: This file is missing on disk; either delete it, or find where it went!
         title: File not found
+      non_manifold:
+        description: This mesh appears to be non-manifold, meaning it has holes or has some faces backwards, and may cause errors when printed. Repair it in a 3d modeling tool such as MeshLab or 3D Builder.
+        title: Non-manifold mesh
+      inside_out:
+        description: This mesh looks like its faces might be pointed the wrong way, which could cause print errors. Repair it in a 3d modeling tool such as MeshLab or 3D Builder.
+        title: Inside-out mesh
     severities:
       danger: Danger
       info: Info