[Bf-cycles] Motion Blur Implementation

[Gavin Howard]

     Hello all,

     I have a question about implementation. I have been told by
Brecht that currently, the Cycles addon exports three steps for motion
blur to the renderer: one at the previous frame, one at the current
frame, and one at the next frame.

     Now, my memory may not be serving me well here, so I may have
gotten the details wrong. But if not, shouldn't the addon actually use
the shutter time to determine the first and third steps? For example,
shouldn't the addon export a step at the start of the shutter time,
one at the current frame, and one at the end of the shutter time?
Also, I think this type of reasoning should apply even when multi-step
(more than 3) motion blur is added. (Multi-step blur is needed for my
Deformation Motion Blur GSoC project, so I will add it over the
summer.)

     In short, I think that the shutter time should be the goto for
exporting motion blur steps. If it is, then just ignore this. But if
it's not, should we change it? Anyway, that's my two cents.

     God Bless,
     Gavin Howard