From 4655ddf3a2b7fee669f7d01f6f70d5f3711205c6 Mon Sep 17 00:00:00 2001
From: Michael Kowalski <makowalski@nvidia.com>
Date: Thu, 4 Aug 2022 11:30:48 -0400
Subject: T90535: import UDIM textures from USD

Added logic to the USD Preview Surface importer to
convert UDIM textures.

Reviewed by: Sybren and Jesse

Differential Revision: https://developer.blender.org/D15379
---
 .../blender/io/usd/intern/usd_reader_material.cc   | 81 ++++++++++++++++++++++
 1 file changed, 81 insertions(+)

(limited to 'source/blender/io/usd/intern')

diff --git a/source/blender/io/usd/intern/usd_reader_material.cc b/source/blender/io/usd/intern/usd_reader_material.cc
index 8feceee55ed..f59b8be147e 100644
--- a/source/blender/io/usd/intern/usd_reader_material.cc
+++ b/source/blender/io/usd/intern/usd_reader_material.cc
@@ -9,8 +9,11 @@
 #include "BKE_node.h"
 #include "BKE_node_tree_update.h"
 
+#include "BLI_fileops.h"
 #include "BLI_math_vector.h"
+#include "BLI_path_util.h"
 #include "BLI_string.h"
+#include "BLI_vector.hh"
 
 #include "DNA_material_types.h"
 
@@ -94,6 +97,60 @@ static void link_nodes(
   nodeAddLink(ntree, source, source_socket, dest, dest_socket);
 }
 
+/* Returns a layer handle retrieved from the given attribute's property specs.
+ * Note that the returned handle may be invalid if no layer could be found. */
+static pxr::SdfLayerHandle get_layer_handle(const pxr::UsdAttribute &attribute)
+{
+  for (auto PropertySpec : attribute.GetPropertyStack(pxr::UsdTimeCode::EarliestTime())) {
+    if (PropertySpec->HasDefaultValue() ||
+        PropertySpec->GetLayer()->GetNumTimeSamplesForPath(PropertySpec->GetPath()) > 0) {
+      return PropertySpec->GetLayer();
+    }
+  }
+
+  return pxr::SdfLayerHandle();
+}
+
+static bool is_udim_path(const std::string &path)
+{
+  return path.find("<UDIM>") != std::string::npos;
+}
+
+/* For the given UDIM path (assumed to contain the UDIM token), returns an array
+ * containing valid tile indices. */
+static blender::Vector<int> get_udim_tiles(const std::string &file_path)
+{
+  char base_udim_path[FILE_MAX];
+  BLI_strncpy(base_udim_path, file_path.c_str(), sizeof(base_udim_path));
+
+  blender::Vector<int> udim_tiles;
+
+  /* Extract the tile numbers from all files on disk. */
+  ListBase tiles = {nullptr, nullptr};
+  int tile_start, tile_range;
+  bool result = BKE_image_get_tile_info(base_udim_path, &tiles, &tile_start, &tile_range);
+  if (result) {
+    LISTBASE_FOREACH (LinkData *, tile, &tiles) {
+      int tile_number = POINTER_AS_INT(tile->data);
+      udim_tiles.append(tile_number);
+    }
+  }
+
+  BLI_freelistN(&tiles);
+
+  return udim_tiles;
+}
+
+/* Add tiles with the given indices to the given image. */
+static void add_udim_tiles(Image *image, const blender::Vector<int> &indices)
+{
+  image->source = IMA_SRC_TILED;
+
+  for (int tile_number : indices) {
+    BKE_image_add_tile(image, tile_number, nullptr);
+  }
+}
+
 /* Returns true if the given shader may have opacity < 1.0, based
  * on heuristics. */
 static bool needs_blend(const pxr::UsdShadeShader &usd_shader)
@@ -600,12 +657,32 @@ void USDMaterialReader::load_tex_image(const pxr::UsdShadeShader &usd_shader,
 
   const pxr::SdfAssetPath &asset_path = file_val.Get<pxr::SdfAssetPath>();
   std::string file_path = asset_path.GetResolvedPath();
+  if (file_path.empty()) {
+    /* No resolved path, so use the asset path (usually
+     * 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()) {
     std::cerr << "WARNING: Couldn't resolve image asset '" << asset_path
               << "' for Texture Image node." << std::endl;
     return;
   }
 
+  /* If this is a UDIM texture, this will store the
+   * UDIM tile indices. */
+  blender::Vector<int> udim_tiles;
+
+  if (is_udim_path(file_path)) {
+    udim_tiles = get_udim_tiles(file_path);
+  }
+
   const char *im_file = file_path.c_str();
   Image *image = BKE_image_load_exists(bmain_, im_file);
   if (!image) {
@@ -614,6 +691,10 @@ void USDMaterialReader::load_tex_image(const pxr::UsdShadeShader &usd_shader,
     return;
   }
 
+  if (udim_tiles.size() > 0) {
+    add_udim_tiles(image, udim_tiles);
+  }
+
   tex_image->id = &image->id;
 
   /* Set texture color space.
-- 
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