Fix #34779: Channels disappear from multilayer exr sequence

Issue was caused by delayed or missing image user frame
number update, which lead to image loading failure in
cases node is updating from image signal callback.

Solved in a way that file from image datablock is used
for sockets detection instead of loading image for
current frame.

1 files changed, 16 insertions, 3 deletions

diff --git a/source/blender/nodes/composite/nodes/node_composite_image.c b/source/blender/nodes/composite/nodes/node_composite_image.c
index c09903ad6c5..e2c4db55fd8 100644
--- a/source/blender/nodes/composite/nodes/node_composite_image.c
+++ b/source/blender/nodes/composite/nodes/node_composite_image.c
@@ -174,11 +174,24 @@ static void cmp_node_image_create_outputs(bNodeTree *ntree, bNode *node)
 {
 	Image *ima= (Image *)node->id;
 	if (ima) {
-		ImageUser *iuser= node->storage;
+		ImageUser *iuser = node->storage;
+		ImageUser load_iuser = {0};
 		ImBuf *ibuf;
-		
+		int offset = BKE_image_sequence_guess_offset(ima);
+
+		/* It is possible that image user in this node is not
+		 * properly updated yet. In this case loading image will
+		 * fail and sockets detection will go wrong.
+		 *
+		 * So we manually construct image user to be sure first
+		 * image from sequence (that one which is set as fileanme
+		 * for image datablock) is used for sockets detection
+		 */
+		load_iuser.ok = 1;
+		load_iuser.framenr = offset;
+
 		/* make sure ima->type is correct */
-		ibuf = BKE_image_acquire_ibuf(ima, iuser, NULL);
+		ibuf = BKE_image_acquire_ibuf(ima, &load_iuser, NULL);
 		
 		if (ima->rr) {
 			RenderLayer *rl= BLI_findlink(&ima->rr->layers, iuser->layer);