From dfcd2eef41b7f786722bac0931bf767eb2681ca0 Mon Sep 17 00:00:00 2001
From: Thomas FORGIONE <thomas.forgione@gmail.com>
Date: Wed, 30 Nov 2016 14:57:58 +0100
Subject: [PATCH] Added stl support

---
 d3/model/basemodel.py |  2 +-
 d3/model/obj.py       |  2 +-
 d3/model/stl.py       | 99 +++++++++++++++++++++++++++++++++++++++++++
 d3/model/tools.py     |  5 +++
 4 files changed, 106 insertions(+), 2 deletions(-)
 create mode 100644 d3/model/stl.py

diff --git a/d3/model/basemodel.py b/d3/model/basemodel.py
index fb0cfe2..820148f 100644
--- a/d3/model/basemodel.py
+++ b/d3/model/basemodel.py
@@ -117,7 +117,7 @@ class ModelParser:
         If the face has a different material than the current material, it will
         create a new mesh part and update the current material.
         """
-        if self.current_part is None or face.material != self.current_part.material:
+        if self.current_part is None or (face.material != self.current_part.material and face.material is not None):
             self.current_part = MeshPart(self)
             self.current_part.material = face.material if face.material is not None else Material.DEFAULT_MATERIAL
             self.parts.append(self.current_part)
diff --git a/d3/model/obj.py b/d3/model/obj.py
index 69f3042..105c44b 100644
--- a/d3/model/obj.py
+++ b/d3/model/obj.py
@@ -122,7 +122,7 @@ class OBJExporter(Exporter):
         faces = sum(map(lambda x: x.faces, self.model.parts), [])
 
         for face in faces:
-            if face.material.name != current_material:
+            if face.material is not None and face.material.name != current_material:
                 current_material = face.material.name
                 string += "usemtl " + current_material + "\n"
             string += "f "
diff --git a/d3/model/stl.py b/d3/model/stl.py
new file mode 100644
index 0000000..3ffda52
--- /dev/null
+++ b/d3/model/stl.py
@@ -0,0 +1,99 @@
+#!/usr/bin/env python
+
+from .basemodel import ModelParser, Exporter, Vertex, FaceVertex, Face
+from .mesh import MeshPart
+
+import os.path
+
+def is_stl(filename):
+    return filename[-4:] == '.stl'
+
+class STLParser(ModelParser):
+
+    def __init__(self):
+        super().__init__()
+        self.parsing_solid = False
+        self.parsing_face = False
+        self.parsing_loop = False
+        self.current_face = None
+        self.face_vertices = None
+
+    def parse_line(self, string):
+
+        if string == '':
+            return
+
+        split = string.split()
+
+        if split[0] == 'solid':
+            self.parsing_solid = True
+            return
+
+        if split[0] == 'endsolid':
+            self.parsing_solid = False
+            return
+
+        if self.parsing_solid:
+
+            if split[0] == 'facet' and split[1] == 'normal':
+                self.parsing_face = True
+                self.face_vertices = [FaceVertex(), FaceVertex(), FaceVertex()]
+                self.current_face = Face(*self.face_vertices)
+                return
+
+            if self.parsing_face:
+
+                if split[0] == 'outer' and split[1] == 'loop':
+                    self.parsing_loop = True
+                    return
+
+                if split[0] == 'endloop':
+                    self.parsing_loop = False
+                    return
+
+                if self.parsing_loop:
+
+                    if split[0] == 'vertex':
+                        current_vertex = Vertex().from_array(split[1:])
+                        self.add_vertex(current_vertex)
+                        self.face_vertices[0].vertex = len(self.vertices) - 1
+                        self.face_vertices.pop(0)
+                        return
+
+                if split[0] == 'endfacet':
+                    self.parsing_face = False
+                    self.add_face(self.current_face)
+                    self.current_face = None
+                    self.face_vertices = None
+
+
+class STLExporter(Exporter):
+    def __init__(self, model):
+        super().__init__(model)
+
+    def __str__(self):
+        string = 'solid {}\n'.format(os.path.basename(self.model.path[:-4]))
+
+        self.model.generate_face_normals()
+
+        faces = sum(map(lambda x: x.faces, self.model.parts), [])
+
+        for face in faces:
+
+            n  = self.model.normals[face.a.normal]
+            v1 = self.model.vertices[face.a.vertex]
+            v2 = self.model.vertices[face.b.vertex]
+            v3 = self.model.vertices[face.c.vertex]
+
+            string += "facet normal {} {} {}\n".format(n.x, n.y, n.z)
+
+            string += "\touter loop\n"
+            string += "\t\tvertex {} {} {}\n".format(v1.x, v1.y, v1.z)
+            string += "\t\tvertex {} {} {}\n".format(v2.x, v2.y, v2.z)
+            string += "\t\tvertex {} {} {}\n".format(v3.x, v3.y, v3.z)
+
+            string += "\tendloop\n"
+            string += "endfacet\n"
+
+        string += 'endsolid {}'.format(os.path.basename(self.model.path[:-4]))
+        return string
diff --git a/d3/model/tools.py b/d3/model/tools.py
index 9795faa..c4548e8 100644
--- a/d3/model/tools.py
+++ b/d3/model/tools.py
@@ -2,6 +2,7 @@
 
 from .obj import is_obj, OBJParser, OBJExporter
 from .ply import is_ply, PLYParser, PLYExporter
+from .stl import is_stl, STLParser, STLExporter
 from .basemodel import ModelParser, Exporter
 
 def load_model(path):
@@ -11,6 +12,8 @@ def load_model(path):
         parser = OBJParser()
     elif is_ply(path):
         parser = PLYParser()
+    elif is_stl(path):
+        parser = STLParser()
     else:
         raise Exception("File format not supported")
 
@@ -25,6 +28,8 @@ def export_model(model, path):
         exporter = OBJExporter(model)
     elif is_ply(path):
         exporter = PLYExporter(model)
+    elif is_stl(path):
+        exporter = STLExporter(model)
     else:
         raise Exception("File format not supported")