Cycles: Add support for motion blur position

This adds an option to control at what time relative to the current frame
the shutter is fully opened. Supported options are:

- Shutter is starting to open at the current frame
- Shutter is fully opened at the current frame
- Shutter is fully closed  at the current frame

Custom shutter time offset is possible, same as custom curve for shutter
openness but those are considered nice things to have rather than something
crucial.

Reviewers: juicyfruit, dingto

Subscribers: venomgfx, hjalti

Differential Revision: https://developer.blender.org/D1380

1 files changed, 12 insertions, 0 deletions

diff --git a/intern/cycles/blender/addon/properties.py b/intern/cycles/blender/addon/properties.py
index 5f65fd7506b..094d68e4f53 100644
--- a/intern/cycles/blender/addon/properties.py
+++ b/intern/cycles/blender/addon/properties.py
@@ -519,6 +519,18 @@ class CyclesRenderSettings(bpy.types.PropertyGroup):
                 min=0.0, max=5.0
                 )
 
+        cls.motion_blur_position = EnumProperty(
+            name="Motion Blur Position",
+            default='CENTER',
+            description="Specifies an offset for the shutter’s time interval "
+                        "which allows to change the motion blur trails",
+            items=(
+                ('START', "Start on Frame", "The shutter opens at the current frame"),
+                ('CENTER', "Center on Frame", "The shutter is open during the current frame"),
+                ('END', "End on Frame", "The shutter closes at the current frame"),
+                ),
+            )
+
     @classmethod
     def unregister(cls):
         del bpy.types.Scene.cycles