Appleseed: Add support for shutter opening curves to camera

[dictoon]

For reference, see https://rmanwiki.pixar.com/display/RFM/Motion+Blur+in+Maya, "Shutter Opening" section.

[Narann]

Maybe a start point.

And here, p.32.

[dictoon]

The change is likely to take place in renderer::Camera::initialize_ray():

sampling_context.split_in_place(1, 1);
ray.m_time =
    ShadingRay::Time::create_with_normalized_time(
        sampling_context.next2<float>(),
        m_shutter_open_time,
        m_shutter_close_time);

The idea is to map sampling_context.next2<float>() to the desired curve before passing it to ShadingRay::Time::create_with_normalized_time().

[Narann]

I want to point what RenderMan do because I think it's the more evolved and interesting.

[dictoon]

That's rather awesome :)

[pjessesco]

Hey I'd like to try this issue.

[dictoon]

Definitely, go for it!

[pjessesco]

@dictoon link is dead :(

[dictoon]

@pjessesco They keep changing their links, it's annoying. Here: https://rmanwiki.pixar.com/display/RFM/Motion+Blur+in+Maya

[dictoon]

@fedormatantsev @pjessesco I think we can consider this done now that we support linear and Bézier opening/closing curves. What do you think?

[fedormatantsev]

@dictoon agree.