Fix error resolving gazebo classic material when loading world

src/SdfEntityCreator.cc

@@ -85,6 +85,7 @@
 #include "gz/sim/components/World.hh"
 
 #include "rendering/MaterialParser/MaterialParser.hh"
+#include "ServerPrivate.hh"
 
 class gz::sim::SdfEntityCreatorPrivate
 {
@@ -808,7 +809,8 @@ Entity SdfEntityCreator::CreateEntities(const sdf::Visual *_visual)
       "https://gazebosim.org/api/sim/8/migrationsdf.html#:~:text=Materials " <<
       "for details." << std::endl;
       std::string scriptUri = visualMaterial.ScriptUri();
-      if (scriptUri != "file://media/materials/scripts/gazebo.material") {
+      if (scriptUri != ServerPrivate::kClassicMaterialScriptUri)
+      {
         gzwarn << "Custom material scripts are not supported."
           << std::endl;
       }

src/Server.cc

@@ -159,7 +159,8 @@ Server::Server(const ServerConfig &_config)
       // 'src/gui_main.cc'.
       errors = sdfRoot.Load(filePath, sdfParserConfig);
       if (errors.empty() || _config.BehaviorOnSdfErrors() !=
-          ServerConfig::SdfErrorBehavior::EXIT_IMMEDIATELY) {
+          ServerConfig::SdfErrorBehavior::EXIT_IMMEDIATELY)
+      {
         if (sdfRoot.Model() == nullptr) {
           this->dataPtr->sdfRoot = std::move(sdfRoot);
         }

src/ServerPrivate.cc

@@ -37,6 +37,9 @@
 using namespace gz;
 using namespace sim;
 
+const char ServerPrivate::kClassicMaterialScriptUri[] =
+    "file://media/materials/scripts/gazebo.material";
+
 /// \brief This struct provides access to the record plugin SDF string
 struct LoggingPlugin
 {
@@ -546,6 +549,12 @@ bool ServerPrivate::ResourcePathsResolveService(
 //////////////////////////////////////////////////
 std::string ServerPrivate::FetchResource(const std::string &_uri)
 {
+  // Handle gazebo classic material URIs.
+  // Return original URI string as the SdfEntityCreator checks for this URI
+  if (_uri == kClassicMaterialScriptUri)
+    return _uri;
+
+  // Fetch resource from fuel
   auto path =
       fuel_tools::fetchResourceWithClient(_uri, *this->fuelClient.get());
 

src/ServerPrivate.hh

@@ -187,6 +187,11 @@ namespace gz
       /// Server. It is used in the SDFormat world generator when saving worlds
       public: std::unordered_map<std::string, std::string> fuelUriMap;
 
+      /// \brief Gazebo classic material URI string
+      /// A URI matching this string indicates that it is a gazebo classic
+      /// material.
+      public: static const char kClassicMaterialScriptUri[];
+
       /// \brief List of names for all worlds loaded in this server.
       private: std::vector<std::string> worldNames;
 

test/integration/material.cc

@@ -296,3 +296,30 @@ TEST_F(MaterialTest, InvalidColor)
   EXPECT_EQ(math::Color(0.0f, 0.0f, 0.0f, 1.0f),
             boxVisualComp->Data().Specular());
 }
+
+TEST_F(MaterialTest, WorldWithClassicMaterial)
+{
+  ServerConfig serverConfig;
+  serverConfig.SetSdfFile(common::joinPaths(PROJECT_SOURCE_PATH,
+      "test", "worlds", "classic_material.sdf"));
+
+  std::cout << "Loading: " << serverConfig.SdfFile() << std::endl;
+  this->StartServer(serverConfig);
+
+  auto model = this->GetModel("box");
+  ASSERT_TRUE(model.Valid(*this->ecm));
+
+  auto boxVisualEntity =
+    this->ecm->EntityByComponents(components::Name("box_visual"));
+  ASSERT_NE(kNullEntity, boxVisualEntity);
+
+  // Blue color
+  auto boxVisualComp =
+    this->ecm->Component<components::Material>(boxVisualEntity);
+  EXPECT_EQ(math::Color(0.0f, 0.0f, 1.0f, 1.0f),
+            boxVisualComp->Data().Ambient());
+  EXPECT_EQ(math::Color(0.0f, 0.0f, 1.0f, 1.0f),
+            boxVisualComp->Data().Diffuse());
+  EXPECT_EQ(math::Color(0.1f, 0.1f, 0.1f, 1.0f),
+            boxVisualComp->Data().Specular());
+}

test/worlds/classic_material.sdf

@@ -0,0 +1,32 @@
+<?xml version="1.0" ?>
+<sdf version="1.6">
+  <world name="default">
+
+    <model name="box">
+      <link name="box_link">
+        <collision name="box_collision">
+          <geometry>
+            <box>
+              <size>1 1 1</size>
+            </box>
+          </geometry>
+        </collision>
+
+        <visual name="box_visual">
+          <geometry>
+            <box>
+              <size>1 1 1</size>
+            </box>
+          </geometry>
+          <material>
+            <script>
+              <uri>file://media/materials/scripts/gazebo.material</uri>
+              <name>Gazebo/Blue</name>
+            </script>
+          </material>
+        </visual>
+      </link>
+    </model>
+
+  </world>
+</sdf>