Fix T64953: Add cryptomatte meta data to file output node.

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

1 files changed, 7 insertions, 2 deletions

diff --git a/source/blender/compositor/operations/COM_OutputFileMultiViewOperation.cpp b/source/blender/compositor/operations/COM_OutputFileMultiViewOperation.cpp
index 21d9177ddd5..0b732357c92 100644
--- a/source/blender/compositor/operations/COM_OutputFileMultiViewOperation.cpp
+++ b/source/blender/compositor/operations/COM_OutputFileMultiViewOperation.cpp
@@ -143,13 +143,14 @@ void OutputOpenExrSingleLayerMultiViewOperation::deinitExecution()
 /************************************ OpenEXR Multilayer Multiview *******************************/
 
 OutputOpenExrMultiLayerMultiViewOperation::OutputOpenExrMultiLayerMultiViewOperation(
+    const Scene *scene,
     const RenderData *rd,
     const bNodeTree *tree,
     const char *path,
     char exr_codec,
     bool exr_half_float,
     const char *viewName)
-    : OutputOpenExrMultiLayerOperation(rd, tree, path, exr_codec, exr_half_float, viewName)
+    : OutputOpenExrMultiLayerOperation(scene, rd, tree, path, exr_codec, exr_half_float, viewName)
 {
 }
 
@@ -195,12 +196,16 @@ void *OutputOpenExrMultiLayerMultiViewOperation::get_handle(const char *filename
     BLI_make_existing_file(filename);
 
     /* prepare the file with all the channels for the header */
-    if (IMB_exr_begin_write(exrhandle, filename, width, height, this->m_exr_codec, nullptr) == 0) {
+    StampData *stamp_data = createStampData();
+    if (IMB_exr_begin_write(exrhandle, filename, width, height, this->m_exr_codec, stamp_data) ==
+        0) {
       printf("Error Writing Multilayer Multiview Openexr\n");
       IMB_exr_close(exrhandle);
+      BKE_stamp_data_free(stamp_data);
     }
     else {
       IMB_exr_clear_channels(exrhandle);
+      BKE_stamp_data_free(stamp_data);
       return exrhandle;
     }
   }