Merge pull request #447 from nyalldawson/draco_fix

Handle the situation where the recorded component type does not match the required type for the actual number of stored points
syoyo · Sep 2, 2023 · 51530ee · 51530ee
2 parents acf1e8a + 6e3d666
commit 51530ee
Showing 1 changed file with 46 additions and 11 deletions.
diff --git a/tiny_gltf.h b/tiny_gltf.h
@@ -4873,8 +4873,9 @@ static bool GetAttributeForAllPoints(uint32_t componentType, draco::Mesh *mesh,
 }
 
 static bool ParseDracoExtension(Primitive *primitive, Model *model,
-                                std::string *err,
-                                const Value &dracoExtensionValue) {
+                                std::string *err, std::string *warn,
+                                const Value &dracoExtensionValue,
+                                ParseStrictness strictness) {
   (void)err;
   auto bufferViewValue = dracoExtensionValue.Get("bufferView");
   if (!bufferViewValue.IsInt()) return false;
@@ -4906,6 +4907,33 @@ static bool ParseDracoExtension(Primitive *primitive, Model *model,
 
   // create new bufferView for indices
   if (primitive->indices >= 0) {
+    if (strictness == ParseStrictness::PERMISSIVE) {
+      const draco::PointIndex::ValueType numPoint = mesh->num_points();
+      // handle the situation where the stored component type does not match the
+      // required type for the actual number of stored points
+      int supposedComponentType = TINYGLTF_COMPONENT_TYPE_UNSIGNED_BYTE;
+      if (numPoint < static_cast<draco::PointIndex::ValueType>(
+                         std::numeric_limits<uint8_t>::max())) {
+        supposedComponentType = TINYGLTF_COMPONENT_TYPE_UNSIGNED_BYTE;
+      } else if (
+          numPoint < static_cast<draco::PointIndex::ValueType>(
+                         std::numeric_limits<uint16_t>::max())) {
+        supposedComponentType = TINYGLTF_COMPONENT_TYPE_UNSIGNED_SHORT;
+      } else {
+        supposedComponentType = TINYGLTF_COMPONENT_TYPE_UNSIGNED_INT;
+      }
+
+      if (supposedComponentType > model->accessors[primitive->indices].componentType) {
+        model->accessors[primitive->indices].componentType = supposedComponentType;
+        if (warn) {
+          (*warn) +=
+              "GLTF component type " + std::to_string(model->accessors[primitive->indices].componentType) +
+              " is not sufficient for number of stored points,"
+              " treating as " + std::to_string(supposedComponentType) + "\n";
+        }
+      }
+    }
+
     int32_t componentSize = GetComponentSizeInBytes(
         model->accessors[primitive->indices].componentType);
     Buffer decodedIndexBuffer;
@@ -4971,9 +4999,11 @@ static bool ParseDracoExtension(Primitive *primitive, Model *model,
 }
 #endif
 
-static bool ParsePrimitive(Primitive *primitive, Model *model, std::string *err,
+static bool ParsePrimitive(Primitive *primitive, Model *model,
+                           std::string *err, std::string *warn,
                            const detail::json &o,
-                           bool store_original_json_for_extras_and_extensions) {
+                           bool store_original_json_for_extras_and_extensions,
+                           ParseStrictness strictness) {
   int material = -1;
   ParseIntegerProperty(&material, err, o, "material", false);
   primitive->material = material;
@@ -5022,18 +5052,21 @@ static bool ParsePrimitive(Primitive *primitive, Model *model, std::string *err,
   auto dracoExtension =
       primitive->extensions.find("KHR_draco_mesh_compression");
   if (dracoExtension != primitive->extensions.end()) {
-    ParseDracoExtension(primitive, model, err, dracoExtension->second);
+    ParseDracoExtension(primitive, model, err, warn, dracoExtension->second, strictness);
   }
 #else
   (void)model;
+  (void)warn;
 #endif
 
   return true;
 }
 
-static bool ParseMesh(Mesh *mesh, Model *model, std::string *err,
+static bool ParseMesh(Mesh *mesh, Model *model,
+                      std::string *err, std::string *warn,
                       const detail::json &o,
-                      bool store_original_json_for_extras_and_extensions) {
+                      bool store_original_json_for_extras_and_extensions,
+                      ParseStrictness strictness) {
   ParseStringProperty(&mesh->name, err, o, "name", false);
 
   mesh->primitives.clear();
@@ -5046,8 +5079,9 @@ static bool ParseMesh(Mesh *mesh, Model *model, std::string *err,
              detail::ArrayBegin(detail::GetValue(primObject));
          i != primEnd; ++i) {
       Primitive primitive;
-      if (ParsePrimitive(&primitive, model, err, *i,
-                         store_original_json_for_extras_and_extensions)) {
+      if (ParsePrimitive(&primitive, model, err, warn, *i,
+                         store_original_json_for_extras_and_extensions,
+                         strictness)) {
         // Only add the primitive if the parsing succeeds.
         mesh->primitives.emplace_back(std::move(primitive));
       }
@@ -6078,8 +6112,9 @@ bool TinyGLTF::LoadFromString(Model *model, std::string *err, std::string *warn,
         return false;
       }
       Mesh mesh;
-      if (!ParseMesh(&mesh, model, err, o,
-                     store_original_json_for_extras_and_extensions_)) {
+      if (!ParseMesh(&mesh, model, err, warn, o,
+                     store_original_json_for_extras_and_extensions_,
+                     strictness_)) {
         return false;
       }