add support for object motion blur (issue #16)

engine/__init__.py

@@ -41,10 +41,12 @@ def render(self, scene):
         try:
             if self.error:
                 # We have to re-raise the error from update() here because
-                # we can only use  self.error_set() in this function
+                # this function (render()) is the only one that can use self.error_set()
+                # to show a warning to the user after the render finished.
                 raise self.error
 
             if self._session is None:
+                # session is None, but self.error is not set -> User cancelled.
                 print("Export cancelled by user.")
                 return
 

export/__init__.py

@@ -3,7 +3,7 @@
 from ..bin import pyluxcore
 from .. import utils
 from ..utils import node as utils_node
-from . import blender_object, camera, config, light, material
+from . import blender_object, camera, config, light, material, motion_blur
 from .light import WORLD_BACKGROUND_LIGHT_NAME
 from ..nodes.output import get_active_output
 
@@ -194,6 +194,15 @@ def create_session(self, engine, scene, context=None):
             if engine.test_break():
                 return None
 
+        # Motion blur (TODO: camera blur)
+        if scene.camera:
+            blur_settings = scene.camera.data.luxcore.motion_blur
+
+            if blur_settings.enable and blur_settings.shutter > 0 and blur_settings.object_blur:
+                # Object motion blur
+                motion_blur_props = motion_blur.convert(scene, objs, self.exported_objects)
+                scene_props.Set(motion_blur_props)
+
         # World
         if scene.world and scene.world.luxcore.light != "none":
             engine.update_stats("Export", "World")
@@ -362,7 +371,7 @@ def _scene_edit(self, context, changes, luxcore_scene):
                     continue
 
                 # exported_objects contains instances of ExportedObject and ExportedLight
-                if isinstance(exported_thing, blender_object.ExportedObject):
+                if isinstance(exported_thing, utils.ExportedObject):
                     remove_func = luxcore_scene.DeleteObject
                 else:
                     remove_func = luxcore_scene.DeleteLight
@@ -385,3 +394,39 @@ def _scene_edit(self, context, changes, luxcore_scene):
                 props.Set(world_props)
 
         return props
+
+    # def _motion_blur(self, scene, scene_props, objs, step, time):
+    #     """
+    #     Create motion blur properties for all objs.
+    #     You have to call this function at least two times to get valid motion blur properties.
+    #     """
+    #     for obj in objs:
+    #         # TODO: check if object is even moved (compare matrices?)
+    #
+    #         if obj.type == "LAMP" and obj.data.type == "AREA":
+    #             # TODO: Area lights need special matrix calculation
+    #             continue
+    #
+    #         key = utils.make_key(obj)
+    #
+    #         try:
+    #             exported_thing = self.exported_objects[key]
+    #         except KeyError:
+    #             # This is not a problem, objects are skipped during epxort for various reasons
+    #             continue
+    #
+    #         for luxcore_name in exported_thing.luxcore_names:
+    #             # exported_objects contains instances of ExportedObject and ExportedLight
+    #             if isinstance(exported_thing, utils.ExportedObject):
+    #                 prefix = "scene.objects." + luxcore_name + "."
+    #             else:
+    #                 prefix = "scene.lights." + luxcore_name + "."
+    #
+    #             matrix_raw = obj.matrix_world.copy()
+    #             matrix = utils.matrix_to_list(matrix_raw, scene, apply_worldscale=True, invert=True)
+    #             definitions = {
+    #                 "motion.%d.time" % step: time,
+    #                 "motion.%d.transformation" % step: matrix,
+    #             }
+    #             print("definitions:", definitions)
+    #             scene_props.Set(utils.create_props(prefix, definitions))

export/motion_blur.py

@@ -0,0 +1,91 @@
+import math
+from ..bin import pyluxcore
+from .. import utils
+
+
+def convert(scene, objects, exported_objects):
+    assert scene.camera
+    motion_blur = scene.camera.data.luxcore.motion_blur
+
+    steps = motion_blur.steps
+    assert steps > 1
+
+    step_interval = motion_blur.shutter / (steps - 1)
+    times = [step_interval * step - motion_blur.shutter * 0.5 for step in range(steps)]
+    print("times:", times)
+
+    matrices = _get_matrices(scene, objects, exported_objects, steps, times)
+
+    # Find and delete entries of non-moving objects (where all matrices are equal)
+    for prefix, matrix_steps in list(matrices.items()):
+        # https://stackoverflow.com/a/10285205
+        first = matrix_steps[0]
+        matrices_equal = all(matrix == first for matrix in matrix_steps)
+
+        if matrices_equal:
+            # This object does not need motion blur because it does not move
+            del matrices[prefix]
+
+    # Export the properties for moving objects
+    props = pyluxcore.Properties()
+
+    for prefix, matrix_steps in matrices.items():
+        for step in range(steps):
+            time = times[step]
+            matrix = matrix_steps[step]
+            transformation = utils.matrix_to_list(matrix, scene, apply_worldscale=True, invert=True)
+            definitions = {
+                "motion.%d.time" % step: time,
+                "motion.%d.transformation" % step: transformation,
+            }
+            print("time:", time)
+            props.Set(utils.create_props(prefix, definitions))
+
+    return props
+
+
+def _get_matrices(scene, objects, exported_objects, steps, times):
+    matrices = {}  # {prefix: [matrix1, matrix2, ...]}
+
+    frame_center = scene.frame_current
+    subframe_center = scene.frame_subframe
+    print("orig frame, subframe:", frame_center, subframe_center)
+
+    for step in range(steps):
+        offset = times[step]
+        time = frame_center + subframe_center + offset
+        frame = math.floor(time)
+        subframe = time - frame
+        print("frame, subframe:", frame, subframe)
+        scene.frame_set(frame, subframe)
+
+        for obj in objects:
+            if obj.type == "LAMP" and obj.data.type == "AREA":
+                # TODO: Area lights need special matrix calculation
+                continue
+
+            key = utils.make_key(obj)
+
+            try:
+                exported_thing = exported_objects[key]
+            except KeyError:
+                # This is not a problem, objects are skipped during epxort for various reasons
+                continue
+
+            matrix = obj.matrix_world.copy()
+
+            for luxcore_name in exported_thing.luxcore_names:
+                # exported_objects contains instances of ExportedObject and ExportedLight
+                if isinstance(exported_thing, utils.ExportedObject):
+                    prefix = "scene.objects." + luxcore_name + "."
+                else:
+                    prefix = "scene.lights." + luxcore_name + "."
+
+                if step == 0:
+                    matrices[prefix] = [matrix]
+                else:
+                    matrices[prefix].append(matrix)
+
+    # Restore original frame
+    scene.frame_set(frame_center, subframe_center)
+    return matrices

properties/camera.py

@@ -1,5 +1,6 @@
 import bpy
-from bpy.props import PointerProperty, BoolProperty, FloatProperty
+from bpy.props import PointerProperty, BoolProperty, FloatProperty, IntProperty
+from bpy.types import PropertyGroup
 
 FSTOP_DESC = (
     "Aperture, lower values result in stronger depth of field effect and "
@@ -12,12 +13,27 @@
     "The clipping plane object will not be exported"
 )
 
+SHUTTER_TIME_DESC = "Time in seconds between shutter open and shutter close, higher values lead to more blur"
+
 
 def init():
     bpy.types.Camera.luxcore = PointerProperty(type=LuxCoreCameraProps)
 
 
-class LuxCoreCameraProps(bpy.types.PropertyGroup):
+class LuxCoreMotionBlur(PropertyGroup):
+    """
+    motion_blur.*
+    """
+    enable = BoolProperty(name="Enable Motion Blur", default=False)
+    object_blur = BoolProperty(name="Object", default=True, description="Blur moving objects")
+    camera_blur = BoolProperty(name="Camera", default=True, description="Blur if camera moves")
+    shutter = FloatProperty(name="Shutter (s)", default=0.1, min=0, soft_max=2, description=SHUTTER_TIME_DESC)
+    # TODO: add description about accelerators (Embree only supports 2 steps?) and what happens
+    # if more than 2 steps are used
+    steps = IntProperty(name="Steps", default=2, min=2, description="Number of substeps")
+
+
+class LuxCoreCameraProps(PropertyGroup):
     # TODO descriptions
     use_clipping = BoolProperty(name="Clipping:", default=False)
     use_dof = BoolProperty(name="Use Depth of Field", default=False)
@@ -26,3 +42,5 @@ class LuxCoreCameraProps(bpy.types.PropertyGroup):
     fstop = FloatProperty(name="F-stop", default=2.8, min=0.01, description=FSTOP_DESC)
     use_clipping_plane = BoolProperty(name="Use Clipping Plane:", default=False, description=CLIPPING_PLANE_DESC)
     clipping_plane = PointerProperty(name="Clipping Plane", type=bpy.types.Object, description=CLIPPING_PLANE_DESC)
+
+    motion_blur = PointerProperty(type=LuxCoreMotionBlur)

ui/camera.py

@@ -114,3 +114,29 @@ def draw(self, context):
         col.prop(dof_options, "fstop")
         if dof_options.use_high_quality and hq_support:
             col.prop(dof_options, "blades")
+
+
+class LuxCoreMotionBlur(CameraButtonsPanel, Panel):
+    bl_label = "Motion Blur"
+    COMPAT_ENGINES = {"LUXCORE"}
+
+    def draw_header(self, context):
+        self.layout.prop(context.camera.luxcore.motion_blur, "enable", text="")
+
+    def draw(self, context):
+        layout = self.layout
+        cam = context.camera
+        motion_blur = cam.luxcore.motion_blur
+        layout.active = motion_blur.enable
+
+        split = layout.split()
+
+        col = split.column(align=True)
+        col.prop(motion_blur, "object_blur")
+        col.prop(motion_blur, "camera_blur")
+
+        col = split.column(align=True)
+        col.prop(motion_blur, "shutter")
+        col.prop(motion_blur, "steps")
+
+        layout.label("Note: camera blur not implemented yet", icon="INFO")