Nodes: Introduce custom shader nodes for Mitsuba BSDFs

Author: ros-dorian

mitsuba-blender/__init__.py

@@ -20,7 +20,9 @@
 import sys
 import subprocess
 
-from . import io, engine
+from . import (
+    engine, nodes, properties, operators, ui
+)
 
 def get_addon_preferences(context):
     return context.preferences.addons[__name__].preferences
@@ -69,8 +71,11 @@ def try_register_mitsuba(context):
     prefs.is_mitsuba_initialized = could_init_mitsuba
 
     if could_init_mitsuba:
-        io.register()
+        properties.register()
+        operators.register()
+        ui.register()
         engine.register()
+        nodes.register()
 
     return could_init_mitsuba
 
@@ -80,8 +85,11 @@ def try_unregister_mitsuba():
     This may fail if Mitsuba wasn't found, hence the try catch guard
     '''
     try:
-        io.unregister()
         engine.unregister()
+        nodes.unregister()
+        ui.unregister()
+        operators.unregister()
+        properties.unregister()
         return True
     except RuntimeError:
         return False

mitsuba-blender/engine/final.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/properties.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/io/exporter/__init__.py renamed to mitsuba-blender/exporter/__init__.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/camera.py renamed to mitsuba-blender/exporter/camera.py

@@ -1,29 +1,14 @@
 from mathutils import Matrix
 import numpy as np
-from math import degrees
 
 def export_camera(camera_instance, b_scene, export_ctx):
     #camera
     b_camera = camera_instance.object#TODO: instances here too?
     params = {}
     params['type'] = 'perspective'
-
-    res_x = b_scene.render.resolution_x
-    res_y = b_scene.render.resolution_y
-
-    # Extract fov
-    sensor_fit = b_camera.data.sensor_fit
-    if sensor_fit == 'AUTO':
-        params['fov_axis'] = 'x' if res_x >= res_y else 'y'
-        params['fov'] = degrees(b_camera.data.angle_x)
-    elif sensor_fit == 'HORIZONTAL':
-        params['fov_axis'] = 'x'
-        params['fov'] = degrees(b_camera.data.angle_x)
-    elif sensor_fit == 'VERTICAL':
-        params['fov_axis'] = 'y'
-        params['fov'] = degrees(b_camera.data.angle_y)
-    else:
-        export_ctx.log(f'Unknown \'sensor_fit\' value when exporting camera: {sensor_fit}', 'ERROR')
+    #extract fov
+    params['fov_axis'] = 'x'
+    params['fov'] = b_camera.data.angle_x * 180 / np.pi#TODO: check cam.sensor_fit
 
     #TODO: test other parameters relevance (camera.lens, orthographic_scale, dof...)
     params['near_clip'] = b_camera.data.clip_start
@@ -46,8 +31,8 @@ def export_camera(camera_instance, b_scene, export_ctx):
     film['type'] = 'hdrfilm'
 
     scale = b_scene.render.resolution_percentage / 100
-    film['width'] = int(res_x * scale)
-    film['height'] = int(res_y * scale)
+    film['width'] = int(b_scene.render.resolution_x * scale)
+    film['height'] = int(b_scene.render.resolution_y * scale)
 
 
     if b_scene.render.engine == 'MITSUBA':

mitsuba-blender/io/exporter/export_context.py renamed to mitsuba-blender/exporter/export_context.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/geometry.py renamed to mitsuba-blender/exporter/geometry.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'}
@@ -320,30 +321,32 @@ def cycles_material_to_dict(export_ctx, node):
 
     return params
 
-def get_dummy_material(export_ctx):
-    return {
-        'type': 'diffuse',
-        'reflectance': export_ctx.spectrum([1.0, 0.0, 0.3]),
-    }
-
 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)
-            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)
+            output_node = b_mat.node_tree.nodes["Material Output"]
+            surface_node = output_node.inputs["Surface"].links[0].from_node
+            mat_params = cycles_material_to_dict(export_ctx, surface_node)
+
+        except NotImplementedError as err:
+            export_ctx.log("Export of material %s failed : %s Exporting a dummy texture instead." % (b_mat.name, err.args[0]), 'WARN')
+            mat_params = {'type':'diffuse'}
+            mat_params['reflectance'] = export_ctx.spectrum([1.0,0.0,0.3])
+
     else:
         mat_params = {'type':'diffuse'}
         mat_params['reflectance'] = export_ctx.spectrum(b_mat.diffuse_color)
@@ -407,16 +410,8 @@ def convert_world(export_ctx, world, ignore_background):
 
     params = {}
 
-    if world is None:
-        export_ctx.log('No Blender world to export.', 'INFO')
-        return
-
-    if world.use_nodes and world.node_tree is not None:
-        output_node_id = 'World Output'
-        if output_node_id not in world.node_tree.nodes:
-            export_ctx.log('Failed to export world: Cannot find world output node.', 'WARN')
-            return
-        output_node = world.node_tree.nodes[output_node_id]
+    if world.use_nodes:
+        output_node = world.node_tree.nodes['World Output']
         if not output_node.inputs["Surface"].is_linked:
             return
         surface_node = output_node.inputs["Surface"].links[0].from_node
@@ -488,14 +483,15 @@ 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:
         # Single color field for emission, no nodes
-        params.update({
-            'type': 'constant',
-            'radiance': export_ctx.spectrum(world.color)
-        })
+                params.update({
+                    'type': 'constant',
+                    'radiance': export_ctx.spectrum(world.color)
+                })
 
     if export_ctx.export_ids:
         export_ctx.data_add(params, "World")

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

@@ -176,6 +176,7 @@ def mi_shape_to_bl_node(mi_context, mi_props):
 def mi_texture_to_bl_node(mi_context, mi_props):
     # We only parse bitmap textures
     if mi_props.plugin_name() != 'bitmap':
+        mi_context.log(f'Mitsuba texture "{mi_props.plugin_name()}" not supported.', 'ERROR')
         return None
 
     node = common.create_blender_node(common.BlenderNodeType.IMAGE, id=mi_props.id())
@@ -363,7 +364,7 @@ def instantiate_bl_data_node(mi_context, bl_node):
 ##    Main loading     ##
 #########################
 
-def load_mitsuba_scene(bl_context, bl_scene, bl_collection, filepath, global_mat):
+def load_mitsuba_scene(bl_context, bl_scene, bl_collection, filepath, global_mat, with_mitsuba_nodes):
     ''' Load a Mitsuba scene from an XML file into a Blender scene.
     
     Params
@@ -373,13 +374,14 @@ def load_mitsuba_scene(bl_context, bl_scene, bl_collection, filepath, global_mat
     bl_collection: Blender collection
     filepath: Path to the Mitsuba XML scene file
     global_mat: Axis conversion matrix
+    with_mitsuba_nodes: Should create custom Mitsuba node tree
     '''
     start_time = time.time()
     # Load the Mitsuba XML and extract the objects' properties
     from mitsuba import xml_to_props
     raw_props = xml_to_props(filepath)
     mi_scene_props = common.MitsubaSceneProperties(raw_props)
-    mi_context = common.MitsubaSceneImportContext(bl_context, bl_scene, bl_collection, filepath, mi_scene_props, global_mat)
+    mi_context = common.MitsubaSceneImportContext(bl_context, bl_scene, bl_collection, filepath, mi_scene_props, global_mat, with_mitsuba_nodes)
 
     _, mi_props = mi_scene_props.get_first_of_class('Scene')
     bl_scene_data_node = mi_props_to_bl_data_node(mi_context, 'Scene', mi_props)

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

@@ -201,7 +201,7 @@ def get_first_of_class(self, cls):
 
 class MitsubaSceneImportContext:
     ''' Define a context for the Mitsuba scene importer '''
-    def __init__(self, bl_context, bl_scene, bl_collection, filepath, mi_scene_props, axis_matrix):
+    def __init__(self, bl_context, bl_scene, bl_collection, filepath, mi_scene_props, axis_matrix, with_mitsuba_nodes):
         self.bl_context = bl_context
         self.bl_scene = bl_scene
         self.bl_collection = bl_collection
@@ -210,6 +210,7 @@ def __init__(self, bl_context, bl_scene, bl_collection, filepath, mi_scene_props
         self.mi_scene_props = mi_scene_props
         self.axis_matrix = axis_matrix
         self.axis_matrix_inv = axis_matrix.inverted()
+        self.with_mitsuba_nodes = with_mitsuba_nodes
         self.bl_material_cache = {}
         self.bl_image_cache = {}