Nodes: Introduce custom shader nodes for Mitsuba BSDFs

Author: ros-dorian

.github/workflows/test.yml

@@ -15,7 +15,7 @@ on:
 
 # Workflow steps
 jobs:
-  build:
+  test:
     name: "${{ matrix.environment.os }} | Blender ${{ matrix.blender.version }}"
     runs-on: ${{ matrix.environment.os }}
     strategy:
@@ -81,4 +81,11 @@ jobs:
       run: |
         BLENDER_EXECUTABLE=$(find blender/ -maxdepth 1 -regextype posix-extended -regex '.*blender(.exe)?' -print -quit)
         echo "Blender Executable is $BLENDER_EXECUTABLE"
-        ./$BLENDER_EXECUTABLE -b -noaudio --factory-startup --python scripts/run_tests.py -- -v --cov=mitsuba-blender
+        ./$BLENDER_EXECUTABLE -b -noaudio --factory-startup --python scripts/run_tests.py -- -v --cov=mitsuba-blender --local-tmp
+
+    - name: Recover crash logs
+      if: ${{ failure() }}
+      uses: actions/upload-artifact@v3
+      with:
+        name: "crash-logs-${{ matrix.environment.os }}-blender-${{ matrix.blender.version }}"
+        path: tmp/*crash*.txt

mitsuba-blender/__init__.py

@@ -2,13 +2,19 @@
 import tempfile
 import os
 import numpy as np
-from ..io.exporter import SceneConverter
+from ..exporter import SceneConverter
 
 class MitsubaRenderEngine(bpy.types.RenderEngine):
 
     bl_idname = "MITSUBA"
     bl_label = "Mitsuba"
     bl_use_preview = False
+    bl_use_texture_preview = False
+    # Hide Cycles shader nodes in the shading menu
+    bl_use_shading_nodes_custom = False
+    # FIXME: This is used to get a visual feedback of the shapes,
+    #        it does not produce a correct result.
+    bl_use_eevee_viewport = True
 
     # Init is called whenever a new render engine instance is created. Multiple
     # instances may exist at the same time, for example for a viewport and final

mitsuba-blender/engine/final.py

@@ -397,6 +397,12 @@ class MITSUBA_CAMERA_PT_sampler(bpy.types.Panel):
     bl_space_type = 'PROPERTIES'
     bl_region_type = 'WINDOW'
     bl_context = 'render'
+    COMPAT_ENGINES = {'MITSUBA'}
+
+    @classmethod
+    def poll(cls, context):
+        return context.engine in cls.COMPAT_ENGINES
+
     def draw(self, context):
         layout = self.layout
         if hasattr(context.scene.camera, 'data'):
@@ -410,14 +416,20 @@ class MITSUBA_CAMERA_PT_rfilter(bpy.types.Panel):
     bl_space_type = 'PROPERTIES'
     bl_region_type = 'WINDOW'
     bl_context = 'render'
+    COMPAT_ENGINES = {'MITSUBA'}
+
+    @classmethod
+    def poll(cls, context):
+        return context.engine in cls.COMPAT_ENGINES
+
     def draw(self, context):
         layout = self.layout
         if hasattr(context.scene.camera, 'data'):
             cam_settings = context.scene.camera.data.mitsuba
             layout.prop(cam_settings, "active_rfilter", text="Filter")
             getattr(cam_settings.rfilters, cam_settings.active_rfilter).draw(layout)
 
-def draw_device(self, context):
+def mitsuba_render_draw(self, context):
     scene = context.scene
     layout = self.layout
     layout.use_property_split = True
@@ -429,18 +441,20 @@ def draw_device(self, context):
         col = layout.column()
         col.prop(mts_settings, "variant")
 
-def register():
-    bpy.types.RENDER_PT_context.append(draw_device)
-    bpy.utils.register_class(MitsubaRenderSettings)
-    bpy.utils.register_class(MitsubaCameraSettings)
-    bpy.utils.register_class(MITSUBA_RENDER_PT_integrator)
-    bpy.utils.register_class(MITSUBA_CAMERA_PT_sampler)
-    bpy.utils.register_class(MITSUBA_CAMERA_PT_rfilter)
+classes = [
+    MitsubaRenderSettings,
+    MitsubaCameraSettings,
+    MITSUBA_RENDER_PT_integrator,
+    MITSUBA_CAMERA_PT_sampler,
+    MITSUBA_CAMERA_PT_rfilter,
+]
 
+def register():
+    bpy.types.RENDER_PT_context.append(mitsuba_render_draw)
+    for cls in classes:
+        bpy.utils.register_class(cls)
+    
 def unregister():
-    bpy.types.RENDER_PT_context.remove(draw_device)
-    bpy.utils.unregister_class(MitsubaRenderSettings)
-    bpy.utils.unregister_class(MitsubaCameraSettings)
-    bpy.utils.unregister_class(MITSUBA_RENDER_PT_integrator)
-    bpy.utils.unregister_class(MITSUBA_CAMERA_PT_sampler)
-    bpy.utils.unregister_class(MITSUBA_CAMERA_PT_rfilter)
+    for cls in classes:
+        bpy.utils.unregister_class(cls)
+    bpy.types.RENDER_PT_context.remove(mitsuba_render_draw)

mitsuba-blender/engine/properties.py

@@ -1,18 +1,5 @@
 import os
 
-if "bpy" in locals():
-    import importlib
-    if "export_context" in locals():
-        importlib.reload(export_context)
-    if "materials" in locals():
-        importlib.reload(materials)
-    if "geometry" in locals():
-        importlib.reload(geometry)
-    if "lights" in locals():
-        importlib.reload(lights)
-    if "camera" in locals():
-        importlib.reload(camera)
-
 import bpy
 
 from . import export_context
@@ -53,7 +40,7 @@ def scene_to_dict(self, depsgraph, window_manager):
 
         b_scene = depsgraph.scene #TODO: what if there are multiple scenes?
         if b_scene.render.engine == 'MITSUBA':
-            integrator = getattr(b_scene.mitsuba.available_integrators,b_scene.mitsuba.active_integrator).to_dict()
+            integrator = getattr(b_scene.mitsuba.available_integrators, b_scene.mitsuba.active_integrator).to_dict()
         else:
             integrator = {
                 'type':'path',

mitsuba-blender/io/exporter/__init__.py renamed to mitsuba-blender/exporter/__init__.py

@@ -101,7 +101,8 @@ def export_object(deg_instance, export_ctx, is_particle):
                                         mat_nr)
                 if mts_mesh is not None and mts_mesh.face_count() > 0:
                     converted_parts.append((mat_nr, mts_mesh))
-                    export_material(export_ctx, b_mesh.materials[mat_nr])
+                    b_mat = b_mesh.materials[mat_nr]
+                    export_material(export_ctx, b_mat)
 
         if b_object.type != 'MESH':
             b_object.to_mesh_clear()

mitsuba-blender/io/exporter/camera.py renamed to mitsuba-blender/exporter/camera.py

@@ -1,5 +1,6 @@
 import numpy as np
 from mathutils import Matrix
+from ..utils.nodetree import get_active_output
 from .export_context import Files
 
 RoughnessMode = {'GGX': 'ggx', 'BECKMANN': 'beckmann', 'ASHIKHMIN_SHIRLEY':'beckmann', 'MULTI_GGX':'ggx'}
@@ -340,22 +341,37 @@ def get_dummy_material(export_ctx):
 
 def b_material_to_dict(export_ctx, b_mat):
     ''' Converting one material from Blender / Cycles to Mitsuba'''
+    # NOTE: The evaluated material does not keep references to Mitsuba node trees.
+    #       We need to use the original material instead.
+    original_mat = b_mat.original
 
     mat_params = {}
 
-    if b_mat.use_nodes:
+    if original_mat.mitsuba.node_tree is not None:
+        output_node = get_active_output(original_mat.mitsuba.node_tree)
+        if output_node is not None:
+            mat_params = output_node.to_dict(export_ctx)
+        else:
+            export_ctx.log(f'Material {b_mat.name} does not have an output node.', 'ERROR')
+
+    elif b_mat.use_nodes:
         try:
             output_node_id = 'Material Output'
             if output_node_id in b_mat.node_tree.nodes:
                 output_node = b_mat.node_tree.nodes[output_node_id]
-                surface_node = output_node.inputs["Surface"].links[0].from_node
-                mat_params = cycles_material_to_dict(export_ctx, surface_node)
+                if len(output_node.inputs['Surface'].links) > 0:
+                    surface_node = output_node.inputs["Surface"].links[0].from_node
+                    mat_params = cycles_material_to_dict(export_ctx, surface_node)
+                else:
+                    export_ctx.log(f'Export of material {b_mat.name} failed: Output node is not connected. Exporting a dummy material instead.', 'WARN')
+                    mat_params = get_dummy_material(export_ctx)
             else:
                 export_ctx.log(f'Export of material {b_mat.name} failed: Cannot find material output node. Exporting a dummy material instead.', 'WARN')
                 mat_params = get_dummy_material(export_ctx)
         except NotImplementedError as e:
             export_ctx.log(f'Export of material \'{b_mat.name}\' failed: {e.args[0]}. Exporting a dummy material instead.', 'WARN')
             mat_params = get_dummy_material(export_ctx)
+
     else:
         mat_params = {'type':'diffuse'}
         mat_params['reflectance'] = export_ctx.spectrum(b_mat.diffuse_color)
@@ -500,6 +516,7 @@ def convert_world(export_ctx, world, ignore_background):
                     'type': 'constant',
                     'radiance': export_ctx.spectrum(radiance)
                 })
+
         else:
             raise NotImplementedError("Only Background and Emission nodes are supported as final nodes for World export, got '%s'" % surface_node.name)
     else: