[Bf-committers] platform maintainers: request to update exr lib to 2.0

[Dalai Felinto]

Some questions were raised no IRC, let me clarify some things:

Q: What does it change when we update for 2.0?
A: Nothing, absolutely nothing.

The saved files will be the same as before, and the same goes for reading.
As long as we don't change the Blender code the changes will be invisible
for the user/devs.

Q: What is new in EXR 2.0
A: Mainly Multipart support and Depth Data - from http://www.openexr.com :

"
Deep Data. Pixels can now store a variable length list of samples. The main
rationale behind deep-images is to store multiple values at different
depths for each pixel. Support for hard surface and volumetric
representation requirements for deep compositing workflows.

Multi-part image files. Files can now contain a number of separate, but
related, images in one file. Access to any part is independent of the
others; in particular, no access of data need take place for unrequested
parts.
"

Q: Shouldn't we wait for EXR 2.0.1 ?
A: OpenEXR is been used by many industry stockholders (ILM, Weta, ...).
That doesn't mean openexr is bug-free, but they do have auto-test code and
a Quality and Assurance teams (I'm guessing on the later, but still).

Q: Why do we need EXR 2.0?
(or better, why do the multiview branch needs it)

A.1: To Read-Write the new defacto standard for stereoscopic files.

A.2: To be honest, OpenEXR 1.7.1 already supported MutliView (aka stereo
3d), so at first I thought I wouldn't need that. However I couldn't get
"Save Buffers" or the "FSA" options to work with it. With the old MultiView
format we need to have all the channels of all the views ready at once, in
order to write to the file. With MultiPart we can open the file, render one
view, write one view, render another view, write another view, and then
close the file.

I hope that explains things.
Dalai