glTF exporter: Manage material at object level: instances with different colors

5 files changed, 94 insertions, 52 deletions

diff --git a/io_scene_gltf2/__init__.py b/io_scene_gltf2/__init__.py
index ba8b750e..ce044ab1 100755
--- a/io_scene_gltf2/__init__.py
+++ b/io_scene_gltf2/__init__.py
@@ -15,7 +15,7 @@
 bl_info = {
     'name': 'glTF 2.0 format',
     'author': 'Julien Duroure, Norbert Nopper, Urs Hanselmann, Moritz Becher, Benjamin Schmithüsen, Jim Eckerlein, and many external contributors',
-    "version": (0, 9, 23),
+    "version": (0, 9, 24),
     'blender': (2, 80, 0),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',
diff --git a/io_scene_gltf2/blender/exp/gltf2_blender_extract.py b/io_scene_gltf2/blender/exp/gltf2_blender_extract.py
index 4c6d2555..b48b76ea 100755
--- a/io_scene_gltf2/blender/exp/gltf2_blender_extract.py
+++ b/io_scene_gltf2/blender/exp/gltf2_blender_extract.py
@@ -423,26 +423,23 @@ def extract_primitives(glTF, blender_mesh, blender_vertex_groups, modifiers, exp
     # Directory of materials with its primitive.
     #
     no_material_primitives = {
-        MATERIAL_ID: '',
+        MATERIAL_ID: 0,
         INDICES_ID: [],
         ATTRIBUTES_ID: no_material_attributes
     }
 
-    material_name_to_primitives = {'': no_material_primitives}
+    material_idx_to_primitives = {0: no_material_primitives}
 
     #
 
     vertex_index_to_new_indices = {}
 
-    material_map[''] = vertex_index_to_new_indices
+    material_map[0] = vertex_index_to_new_indices
 
     #
     # Create primitive for each material.
     #
-    for blender_material in blender_mesh.materials:
-        if blender_material is None:
-            continue
-
+    for (mat_idx, _) in enumerate(blender_mesh.materials):
         attributes = {
             POSITION_ATTRIBUTE: [],
             NORMAL_ATTRIBUTE: []
@@ -452,18 +449,18 @@ def extract_primitives(glTF, blender_mesh, blender_vertex_groups, modifiers, exp
             attributes[TANGENT_ATTRIBUTE] = []
 
         primitive = {
-            MATERIAL_ID: blender_material.name,
+            MATERIAL_ID: mat_idx,
             INDICES_ID: [],
             ATTRIBUTES_ID: attributes
         }
 
-        material_name_to_primitives[blender_material.name] = primitive
+        material_idx_to_primitives[mat_idx] = primitive
 
         #
 
         vertex_index_to_new_indices = {}
 
-        material_map[blender_material.name] = vertex_index_to_new_indices
+        material_map[mat_idx] = vertex_index_to_new_indices
 
     tex_coord_max = 0
     if blender_mesh.uv_layers.active:
@@ -519,13 +516,12 @@ def extract_primitives(glTF, blender_mesh, blender_vertex_groups, modifiers, exp
 
         #
 
-        if blender_polygon.material_index < 0 or blender_polygon.material_index >= len(blender_mesh.materials) or \
-                blender_mesh.materials[blender_polygon.material_index] is None:
-            primitive = material_name_to_primitives['']
-            vertex_index_to_new_indices = material_map['']
+        if not blender_polygon.material_index in material_idx_to_primitives:
+            primitive = material_idx_to_primitives[0]
+            vertex_index_to_new_indices = material_map[0]
         else:
-            primitive = material_name_to_primitives[blender_mesh.materials[blender_polygon.material_index].name]
-            vertex_index_to_new_indices = material_map[blender_mesh.materials[blender_polygon.material_index].name]
+            primitive = material_idx_to_primitives[blender_polygon.material_index]
+            vertex_index_to_new_indices = material_map[blender_polygon.material_index]
         #
 
         attributes = primitive[ATTRIBUTES_ID]
@@ -920,7 +916,7 @@ def extract_primitives(glTF, blender_mesh, blender_vertex_groups, modifiers, exp
 
     result_primitives = []
 
-    for material_name, primitive in material_name_to_primitives.items():
+    for material_idx, primitive in material_idx_to_primitives.items():
         export_color = True
 
         #
@@ -993,7 +989,7 @@ def extract_primitives(glTF, blender_mesh, blender_vertex_groups, modifiers, exp
                 pending_attributes[TANGENT_ATTRIBUTE] = []
 
             pending_primitive = {
-                MATERIAL_ID: material_name,
+                MATERIAL_ID: material_idx,
                 INDICES_ID: [],
                 ATTRIBUTES_ID: pending_attributes
             }
diff --git a/io_scene_gltf2/blender/exp/gltf2_blender_gather_mesh.py b/io_scene_gltf2/blender/exp/gltf2_blender_gather_mesh.py
index 7e24319f..c2202b9e 100755
--- a/io_scene_gltf2/blender/exp/gltf2_blender_gather_mesh.py
+++ b/io_scene_gltf2/blender/exp/gltf2_blender_gather_mesh.py
@@ -13,7 +13,7 @@
 # limitations under the License.
 
 import bpy
-from typing import Optional, Dict, List, Any
+from typing import Optional, Dict, List, Any, Tuple
 from .gltf2_blender_export_keys import MORPH
 from io_scene_gltf2.blender.exp.gltf2_blender_gather_cache import cached
 from io_scene_gltf2.io.com import gltf2_io
@@ -23,21 +23,22 @@ from io_scene_gltf2.io.com.gltf2_io_debug import print_console
 
 
 @cached
-def gather_mesh(blender_mesh: bpy.types.Mesh,
+def gather_mesh(blender_mesh_name: str,
                 vertex_groups: Optional[bpy.types.VertexGroups],
                 modifiers: Optional[bpy.types.ObjectModifiers],
                 skip_filter: bool,
+                material_names: Tuple[str],
                 export_settings
                 ) -> Optional[gltf2_io.Mesh]:
-    if not skip_filter and not __filter_mesh(blender_mesh, vertex_groups, modifiers, export_settings):
+    if not skip_filter and not __filter_mesh(blender_mesh_name, vertex_groups, modifiers, export_settings):
         return None
 
     mesh = gltf2_io.Mesh(
-        extensions=__gather_extensions(blender_mesh, vertex_groups, modifiers, export_settings),
-        extras=__gather_extras(blender_mesh, vertex_groups, modifiers, export_settings),
-        name=__gather_name(blender_mesh, vertex_groups, modifiers, export_settings),
-        primitives=__gather_primitives(blender_mesh, vertex_groups, modifiers, export_settings),
-        weights=__gather_weights(blender_mesh, vertex_groups, modifiers, export_settings)
+        extensions=__gather_extensions(blender_mesh_name, vertex_groups, modifiers, export_settings),
+        extras=__gather_extras(blender_mesh_name, vertex_groups, modifiers, export_settings),
+        name=__gather_name(blender_mesh_name, vertex_groups, modifiers, export_settings),
+        primitives=__gather_primitives(blender_mesh_name, vertex_groups, modifiers, material_names, export_settings),
+        weights=__gather_weights(blender_mesh_name, vertex_groups, modifiers, export_settings)
     )
 
     if len(mesh.primitives) == 0:
@@ -46,17 +47,18 @@ def gather_mesh(blender_mesh: bpy.types.Mesh,
     return mesh
 
 
-def __filter_mesh(blender_mesh: bpy.types.Mesh,
+def __filter_mesh(blender_mesh_name: str,
                   vertex_groups: Optional[bpy.types.VertexGroups],
                   modifiers: Optional[bpy.types.ObjectModifiers],
                   export_settings
                   ) -> bool:
+    blender_mesh = bpy.data.meshes[blender_mesh_name]
     if blender_mesh.users == 0:
         return False
     return True
 
 
-def __gather_extensions(blender_mesh: bpy.types.Mesh,
+def __gather_extensions(blender_mesh_name: str,
                         vertex_groups: Optional[bpy.types.VertexGroups],
                         modifiers: Optional[bpy.types.ObjectModifiers],
                         export_settings
@@ -64,11 +66,12 @@ def __gather_extensions(blender_mesh: bpy.types.Mesh,
     return None
 
 
-def __gather_extras(blender_mesh: bpy.types.Mesh,
+def __gather_extras(blender_mesh_name: str,
                     vertex_groups: Optional[bpy.types.VertexGroups],
                     modifiers: Optional[bpy.types.ObjectModifiers],
                     export_settings
                     ) -> Optional[Dict[Any, Any]]:
+    blender_mesh = bpy.data.meshes[blender_mesh_name]
     extras = {}
 
     if export_settings['gltf_extras']:
@@ -89,28 +92,33 @@ def __gather_extras(blender_mesh: bpy.types.Mesh,
     return None
 
 
-def __gather_name(blender_mesh: bpy.types.Mesh,
+def __gather_name(blender_mesh_name: str,
                   vertex_groups: Optional[bpy.types.VertexGroups],
                   modifiers: Optional[bpy.types.ObjectModifiers],
                   export_settings
                   ) -> str:
-    return blender_mesh.name
+    return blender_mesh_name
 
 
-def __gather_primitives(blender_mesh: bpy.types.Mesh,
+def __gather_primitives(blender_mesh_name: str,
                         vertex_groups: Optional[bpy.types.VertexGroups],
                         modifiers: Optional[bpy.types.ObjectModifiers],
+                        material_names: Tuple[str],
                         export_settings
                         ) -> List[gltf2_io.MeshPrimitive]:
-    return gltf2_blender_gather_primitives.gather_primitives(blender_mesh, vertex_groups, modifiers, export_settings)
+    return gltf2_blender_gather_primitives.gather_primitives(blender_mesh_name,
+                                                             vertex_groups,
+                                                             modifiers,
+                                                             material_names,
+                                                             export_settings)
 
 
-def __gather_weights(blender_mesh: bpy.types.Mesh,
+def __gather_weights(blender_mesh_name: str,
                      vertex_groups: Optional[bpy.types.VertexGroups],
                      modifiers: Optional[bpy.types.ObjectModifiers],
                      export_settings
                      ) -> Optional[List[float]]:
-
+    blender_mesh = bpy.data.meshes[blender_mesh_name]
     if not export_settings[MORPH] or not blender_mesh.shape_keys:
         return None
 
diff --git a/io_scene_gltf2/blender/exp/gltf2_blender_gather_nodes.py b/io_scene_gltf2/blender/exp/gltf2_blender_gather_nodes.py
index 4af4f043..ba303c42 100755
--- a/io_scene_gltf2/blender/exp/gltf2_blender_gather_nodes.py
+++ b/io_scene_gltf2/blender/exp/gltf2_blender_gather_nodes.py
@@ -241,7 +241,13 @@ def __gather_mesh(blender_object, export_settings):
         blender_mesh = blender_object.data
         skip_filter = False
 
-    result = gltf2_blender_gather_mesh.gather_mesh(blender_mesh, vertex_groups, modifiers, skip_filter, export_settings)
+    material_names = tuple([ms.material.name for ms in blender_object.material_slots])
+    result = gltf2_blender_gather_mesh.gather_mesh(blender_mesh.name,
+                                                   vertex_groups,
+                                                   modifiers,
+                                                   skip_filter,
+                                                   material_names,
+                                                   export_settings)
 
     if export_settings[gltf2_blender_export_keys.APPLY]:
         blender_mesh_owner.to_mesh_clear()
diff --git a/io_scene_gltf2/blender/exp/gltf2_blender_gather_primitives.py b/io_scene_gltf2/blender/exp/gltf2_blender_gather_primitives.py
index e7c21276..403ca5eb 100755
--- a/io_scene_gltf2/blender/exp/gltf2_blender_gather_primitives.py
+++ b/io_scene_gltf2/blender/exp/gltf2_blender_gather_primitives.py
@@ -13,7 +13,7 @@
 # limitations under the License.
 
 import bpy
-from typing import List, Optional
+from typing import List, Optional, Tuple
 
 from .gltf2_blender_export_keys import NORMALS, MORPH_NORMAL, TANGENTS, MORPH_TANGENT, MORPH
 
@@ -32,9 +32,10 @@ from io_scene_gltf2.io.com.gltf2_io_debug import print_console
 
 @cached
 def gather_primitives(
-        blender_mesh: bpy.types.Mesh,
+        blender_mesh_name: str,
         vertex_groups: Optional[bpy.types.VertexGroups],
         modifiers: Optional[bpy.types.ObjectModifiers],
+        material_names: Tuple[str],
         export_settings
         ) -> List[gltf2_io.MeshPrimitive]:
     """
@@ -43,33 +44,64 @@ def gather_primitives(
     :return: a list of glTF2 primitives
     """
     primitives = []
-    blender_primitives = gltf2_blender_extract.extract_primitives(
-        None, blender_mesh, vertex_groups, modifiers, export_settings)
+
+    blender_primitives = __gather_cache_primitives(blender_mesh_name,
+        vertex_groups, modifiers, export_settings)
 
     for internal_primitive in blender_primitives:
+        material_idx = internal_primitive['material']
+        double_sided = False
+        material = None
+        try:
+            blender_material = bpy.data.materials[material_names[material_idx]]
+            double_sided = not blender_material.use_backface_culling
+            material = gltf2_blender_gather_materials.gather_material(blender_material,
+                                                                  double_sided,
+                                                                  export_settings)
+        except IndexError:
+            # no material at that index
+            pass
+
 
         primitive = gltf2_io.MeshPrimitive(
-            attributes=__gather_attributes(internal_primitive, blender_mesh, modifiers, export_settings),
+            attributes=internal_primitive['attributes'],
             extensions=None,
             extras=None,
-            indices=__gather_indices(internal_primitive, blender_mesh, modifiers, export_settings),
-            material=__gather_materials(internal_primitive, modifiers, export_settings),
+            indices=internal_primitive['indices'],
+            material=material,
             mode=None,
-            targets=__gather_targets(internal_primitive, blender_mesh, modifiers, export_settings)
+            targets=internal_primitive['targets']
         )
         primitives.append(primitive)
 
     return primitives
 
+@cached
+def __gather_cache_primitives(
+        blender_mesh_name: str,
+        vertex_groups: Optional[bpy.types.VertexGroups],
+        modifiers: Optional[bpy.types.ObjectModifiers],
+        export_settings
+) -> List[dict]:
+    """
+    Gather parts that are identical for instances, i.e. excluding materials
+    """
+    blender_mesh = bpy.data.meshes[blender_mesh_name]
+    primitives = []
+
+    blender_primitives = gltf2_blender_extract.extract_primitives(
+        None, blender_mesh, vertex_groups, modifiers, export_settings)
 
-def __gather_materials(blender_primitive, modifiers, export_settings):
-    if not blender_primitive['material']:
-        # TODO: fix 'extract_primitives' so that the value of 'material' is None and not empty string
-        return None
-    material = bpy.data.materials[blender_primitive['material']]
-    material_double_sided = not material.use_backface_culling
-    return gltf2_blender_gather_materials.gather_material(material, material_double_sided, export_settings)
+    for internal_primitive in blender_primitives:
+        primitive = {
+            "attributes": __gather_attributes(internal_primitive, blender_mesh, modifiers, export_settings),
+            "indices": __gather_indices(internal_primitive, blender_mesh, modifiers, export_settings),
+            "material": internal_primitive['material'],
+            "targets": __gather_targets(internal_primitive, blender_mesh, modifiers, export_settings)
+        }
+        primitives.append(primitive)
 
+    return primitives
 
 def __gather_indices(blender_primitive, blender_mesh, modifiers, export_settings):
     indices = blender_primitive['indices']