[Bf-cycles] Motion Blur Implementation

[Brecht Van Lommel]

Yes Blender supports this, it does scene.frame_set(frame, 0.0) now,
the second value is a subframe value between 0.0 and 1.0.

On Mon, Jun 10, 2013 at 4:58 PM, Gavin Howard <gavin.d.howard at gmail.com> wrote:
>      Hello,
>
>      Does Blender allow exporting at arbitrary subframes? If not, that might
> be a problem. If so, then Stuart has me exploring the code, and I think that
> I could write the patch while doing so. Does that sound okay?
>
>      God Bless,
>      Gavin Howard
>
> On Jun 9, 2013 6:34 AM, "Brecht Van Lommel" <brechtvanlommel at pandora.be>
> wrote:
>>
>> We should support exporting at the exact shutter time. At the time I
>> implemented motion blur evaluation at subframes was actually broken
>> for shape keys and physics systems so I didn't use it, but that has
>> been fixed since.
>>
>> However, exporting motion from the frame positions may be useful to
>> keep as it may give more predictable results in some cases. When
>> you're editing animations that's the only thing you actually see in
>> animation playback, so the motion between those frames may contain
>> some unexpected things that you don't want to render.
>>
>> I don't know how common that is, did not look at .blend files yet to
>> see how different the results are, if it is an issue we should
>> probably have an option (off by default) to only export motion from
>> integer frame numbers and no subframes.
>>
>> On Sat, Jun 8, 2013 at 7:36 PM, Gavin Howard <gavin.d.howard at gmail.com>
>> wrote:
>> >      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
>> > _______________________________________________
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