From a42263bdbac80d639408a874a92619e22cc50508 Mon Sep 17 00:00:00 2001
From: Thomas Gamper <tgamper@ptc.com>
Date: Mon, 5 Feb 2024 15:42:49 +0100
Subject: [PATCH] tiny_gltf.h - parse node and material lods

---
 tiny_gltf.h | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/tiny_gltf.h b/tiny_gltf.h
index 7c7227c..6a04d6d 100644
--- a/tiny_gltf.h
+++ b/tiny_gltf.h
@@ -764,6 +764,7 @@ struct Material {
   std::string alphaMode{"OPAQUE"}; // default "OPAQUE"
   double alphaCutoff{0.5};        // default 0.5
   bool doubleSided{false};        // default false
+  std::vector<int> lods;          // level of detail materials (MSFT_lod)
 
   PbrMetallicRoughness pbrMetallicRoughness;
 
@@ -1018,6 +1019,7 @@ class Node {
   int mesh{-1};
   int light{-1};    // light source index (KHR_lights_punctual)
   int emitter{-1};  // audio emitter index (KHR_audio)
+  std::vector<int> lods; // level of detail nodes (MSFT_lod)
   std::vector<int> children;
   std::vector<double> rotation;     // length must be 0 or 4
   std::vector<double> scale;        // length must be 0 or 3
@@ -5165,6 +5167,24 @@ static bool ParseNode(Node *node, std::string *err, const detail::json &o,
   }
   node->emitter = emitter;
 
+  node->lods.clear();
+  if (node->extensions.count("MSFT_lod") != 0) {
+    auto const &msft_lod_ext = node->extensions["MSFT_lod"];
+    if (msft_lod_ext.Has("ids")) {
+      auto idsArr = msft_lod_ext.Get("ids");
+      for (size_t i = 0; i < idsArr.ArrayLen(); ++i) {
+        node->lods.emplace_back(idsArr.Get(i).GetNumberAsInt());
+      }
+    } else {
+      if (err) {
+        *err +=
+            "Node has extension MSFT_lod, but does not reference "
+            "other nodes via their ids.\n";
+      }
+      return false;
+    }
+  }
+
   return true;
 }
 
@@ -5364,6 +5384,24 @@ static bool ParseMaterial(Material *material, std::string *err, std::string *war
   ParseExtrasAndExtensions(material, err, o,
                            store_original_json_for_extras_and_extensions);
 
+  material->lods.clear();
+  if (material->extensions.count("MSFT_lod") != 0) {
+    auto const &msft_lod_ext = material->extensions["MSFT_lod"];
+    if (msft_lod_ext.Has("ids")) {
+      auto idsArr = msft_lod_ext.Get("ids");
+      for (size_t i = 0; i < idsArr.ArrayLen(); ++i) {
+        material->lods.emplace_back(idsArr.Get(i).GetNumberAsInt());
+      }
+    } else {
+      if (err) {
+        *err +=
+            "Material has extension MSFT_lod, but does not reference "
+            "other materials via their ids.\n";
+      }
+      return false;
+    }
+  }
+
   return true;
 }