A couple more changes to the file and image nodes to improve access to layers that don't follow Blender's rlayer.rpass naming scheme.

--- Changes to File Output node ---
* Flat layer names in EXR multilayer files.

 For a socket with name "AAA" the previous resulting EXR layer name would be "AAA.AAA", i.e. the render layer as well as render pass would use the socket name.

 Now the "render_layer.render_pass" scheme is ignored in multilayer files, socket names are directly written to EXR layers (EXR layer name is "AAA" in this example). If sockets should have a notion of "render layer" this can still be achieved by explicitly adding a separator, e.g. "AAA.BBB". When loading such layers into a Blender Image struct, the name is interpreted as a "render_layer.render_pass" again (although the image node does not care about it, see below).

* Socket sub-paths (for singlelayer) or layer names (for multilayer) are stored in dedicated string variables in the socket storage data. This way the RNA can define precise string subtypes (PROP_FILEPATH) and length. The file/layer slots are defined as separate structs with own name properties in the RNA as well, so they can be used nicely with the list template.

* Ensure unique socket paths/layer names to prevent overwriting of files and layers respectively.

--- Changes to Image node ---
* Loading multilayer OpenEXR files has improved layer name splitting into render layer + render pass names now. This properly supports arbitrary EXR layer names now.
  Example:

 OpenEXR layer name:   AAA.BBB.CCC

 is split into

 Render layer name:    AAA.BBB
 Render pass name:     CCC

 If the layer name has no '.' separators the render layer name is empty.

* Image node ignores the selected render layer in the image user data. Instead all existing layers are displayed at the same time by combining the render layer names with render pass names again, to reconstruct the original EXR layer name. This avoids the problem that render layers with empty name are not selectetable in the dropdown and allows using all image layers at the same time without duplicating the node.

1 files changed, 15 insertions, 2 deletions

diff --git a/source/blender/makesdna/DNA_node_types.h b/source/blender/makesdna/DNA_node_types.h
index 6874e8de4f1..6fbaf1723bc 100644
--- a/source/blender/makesdna/DNA_node_types.h
+++ b/source/blender/makesdna/DNA_node_types.h
@@ -324,6 +324,14 @@ typedef struct NodeImageAnim {
 	short pad;
 } NodeImageAnim;
 
+/* layer info for image node outputs */
+typedef struct NodeImageLayer {
+	/* index in the Image->layers and Image->layers->passes lists */
+	int layer_index, pass_index;
+	/* render pass flag, in case this is an original render pass */
+	int pass_flag;
+} NodeImageLayer;
+
 typedef struct NodeBlurData {
 	short sizex, sizey;
 	short samples, maxspeed, minspeed, relative, aspect;
@@ -364,11 +372,16 @@ typedef struct NodeImageMultiFile {
 	int pad;
 } NodeImageMultiFile;
 typedef struct NodeImageMultiFileSocket {
+	/* single layer file output */
 	short use_render_format  DNA_DEPRECATED;
 	short use_node_format;	/* use overall node image format */
-	int pad2;
-	char path[1024];	/* 1024 = FILE_MAX */
+	int pad1;
+	char path[1024];		/* 1024 = FILE_MAX */
 	ImageFormatData format;
+	
+	/* multilayer output */
+	char layer[30];		/* EXR_TOT_MAXNAME-2 ('.' and channel char are appended) */
+	char pad2[2];
 } NodeImageMultiFileSocket;
 
 typedef struct NodeChroma {