[Bf-blender-cvs] [61a9ee88a34] universal-scene-description: USD import: handle context-dependent UDIM paths.

[Michael Kowalski]

Commit: 61a9ee88a34d2db3fed7a50b2fa9aad030bb5f18
Author: Michael Kowalski
Date:   Thu Sep 29 20:16:07 2022 -0400
Branches: universal-scene-description
https://developer.blender.org/rB61a9ee88a34d2db3fed7a50b2fa9aad030bb5f18

USD import: handle context-dependent UDIM paths.

This change helps address the issue where contex-dependent
UDIM texture paths (e.g., '0/foo.<UDIM>.png') were not getting
resolved by the call to SdfLayer::::ComputeAbsolutePath().
To work around this limitation, I updated the code to compute
the absolute path on just the parent directory portion of
the UDIM file path. This makes the simplifying assumption that
context-dependent asset paths are essentially relative paths,
which might not always be correct.  It's not clear how
else to efficiently address this without performing a
potentially expensive search.

===================================================================

M	source/blender/io/usd/intern/usd_reader_material.cc

===================================================================

diff --git a/source/blender/io/usd/intern/usd_reader_material.cc b/source/blender/io/usd/intern/usd_reader_material.cc
index 606a8395929..3376a930926 100644
--- a/source/blender/io/usd/intern/usd_reader_material.cc
+++ b/source/blender/io/usd/intern/usd_reader_material.cc
@@ -752,10 +752,37 @@ void USDMaterialReader::load_tex_image(const pxr::UsdShadeShader &usd_shader,
      * necessary for UDIM paths). */
     file_path = asset_path.GetAssetPath();
 
-    /* Texture paths are frequently relative to the USD, so get
-     * the absolute path. */
-    if (pxr::SdfLayerHandle layer_handle = get_layer_handle(file_input.GetAttr())) {
-      file_path = layer_handle->ComputeAbsolutePath(file_path);
+    if (!file_path.empty() && is_udim_path(file_path)) {
+      /* Texture paths are frequently relative to the USD, so get
+       * the absolute path. */
+      if (pxr::SdfLayerHandle layer_handle = get_layer_handle(file_input.GetAttr())) {
+
+        /* SdfLayer::ComputeAbsolutePath() doesn' work for context-dependent paths
+         * where the file name has a UDIM token (e.g., '0/foo.<UDIM>.png').
+         * We therefore compute the absolube path of the parent directory of the
+         * UDIM file. */
+
+        char file[FILE_MAXFILE];
+        char dir[FILE_MAXDIR];
+        BLI_split_dirfile(file_path.c_str(), dir, file, sizeof(dir), sizeof(file));
+
+        if (strlen(dir) == 0) {
+          /* No directory in path, assume asset is a sibling of the layer. */
+          dir[0] = '.';
+          dir[1] = '\0';
+        }
+
+        /* Get the absolute path of the directory relative to the layer. */
+        std::string dir_abs_path = layer_handle->ComputeAbsolutePath(dir);
+
+        char result[FILE_MAX];
+        /* Finally, join the original file name with the absolute path. */
+        BLI_path_join(result, FILE_MAX, dir_abs_path.c_str(), file, nullptr);
+
+        /* Use forward slashes. */
+        BLI_str_replace_char(result, SEP, ALTSEP);
+        file_path = result;
+      }
     }
   }