Utility to construct a cryptomatte session from a render result or
openexr file. This will allow D3959 to be more aware of the context
it is working on and would also support external render engines in
the cryptomatte color picker.
This patch adds manifest parsing to Cryptomatte. Normally when loading
cryptomatte layer from an OpenEXR file the manifest contains data to
convert a hash to its original name of the object/material. In the
future we want to use this to support lookup of cryptomatte
hashes and show it to the user.
Currently this logic isn't available to users (for now), but is required
by D3959 where a new cryptomatte workflow is implemented.
This change will try to add meta data when using a multilayered open
exr file output node in the compositor. It adds the current scene meta
data and converts existing cryptomatte keys so it follows the
naming that is configured in the file output node.
This change supports the basic use-case where the compositor is
used to output cryptomatte layers with a different naming scheme to
support external compositors. In this case the Multilayered OpenEXR
files are used and the meta data is read from the render result.
Meta data is found when render layer node is connected with the
file output node without any other nodes in between. Redirects and empty
node groups are allowed.
The patch has been verified to work with external compositors.
See https://devtalk.blender.org/t/making-sense-of-cryptomatte-usage-in-third-party-programs/16576/17
See patch for example files.
Reviewed By: Sergey Sharybin
Differential Revision: https://developer.blender.org/D10016
