Helper function to get a scene (#320)

Signed-off-by: Louise Poubel <louise@openrobotics.org>

include/ignition/rendering/RenderingIface.hh

@@ -24,6 +24,7 @@
 
 #include "ignition/rendering/config.hh"
 #include "ignition/rendering/Export.hh"
+#include "ignition/rendering/RenderTypes.hh"
 
 namespace ignition
 {
@@ -131,6 +132,17 @@ namespace ignition
     /// \param[in] _paths The list of the plugin paths
     IGNITION_RENDERING_VISIBLE
     void setPluginPaths(const std::list<std::string> &_paths);
+
+    /// \brief Most applications will only have one rendering engine loaded
+    /// at a time, and only one scene within that. This helper function gets
+    /// the first scene that can be found in the first loaded rendering engine.
+    ///
+    /// It's not recommended to call this function when there's more than one
+    /// engine or scene.
+    ///
+    /// \return Pointer to a scene that was found, null if no scene is loaded.
+    IGNITION_RENDERING_VISIBLE
+    ScenePtr sceneFromFirstRenderEngine();
     }
   }
 }

ogre/src/OgreRenderEngine.cc

@@ -648,9 +648,6 @@ std::string OgreRenderEngine::CreateRenderWindow(const std::string &_handle,
   // Hide window if dimensions are less than or equal to one.
   params["border"] = "none";
 
-  std::ostringstream stream;
-  stream << "OgreWindow(0)" << "_" << _handle;
-
   // Needed for retina displays
   params["contentScalingFactor"] = std::to_string(_ratio);
 
@@ -660,9 +657,12 @@ std::string OgreRenderEngine::CreateRenderWindow(const std::string &_handle,
     params["currentGLContext"] = "true";
   }
 
+  std::ostringstream stream;
   int attempts = 0;
-  while (window == nullptr && (attempts++) < 10)
+  while (window == nullptr && attempts < 10)
   {
+    stream.str("");
+    stream << "OgreWindow(" << attempts << ")" << "_" << _handle;
     try
     {
       window = this->ogreRoot->createRenderWindow(
@@ -674,6 +674,7 @@ std::string OgreRenderEngine::CreateRenderWindow(const std::string &_handle,
              << "]. Exception [" << _e.what() << "]" << std::endl;
       window = nullptr;
     }
+    attempts++;
   }
 
   if (attempts >= 10)

src/RenderingIface.cc

@@ -14,8 +14,13 @@
  * limitations under the License.
  *
  */
+
+#include "ignition/common/Console.hh"
+
+#include "ignition/rendering/RenderEngine.hh"
 #include "ignition/rendering/RenderingIface.hh"
 #include "ignition/rendering/RenderEngineManager.hh"
+#include "ignition/rendering/Scene.hh"
 
 namespace ignition
 {
@@ -120,6 +125,59 @@ void setPluginPaths(const std::list<std::string> &_paths)
 {
   RenderEngineManager::Instance()->SetPluginPaths(_paths);
 }
+
+//////////////////////////////////////////////////
+ScenePtr sceneFromFirstRenderEngine()
+{
+  auto loadedEngNames = ignition::rendering::loadedEngines();
+  if (loadedEngNames.empty())
+  {
+    igndbg << "No rendering engine is loaded yet" << std::endl;
+    return nullptr;
+  }
+
+  auto engineName = loadedEngNames[0];
+  if (loadedEngNames.size() > 1)
+  {
+    ignwarn << "More than one engine is available. "
+      << "Using engine [" << engineName << "]" << std::endl;
+  }
+
+  auto engine = ignition::rendering::engine(engineName);
+  if (!engine)
+  {
+    ignerr << "Internal error: failed to load engine [" << engineName
+      << "]." << std::endl;
+    return nullptr;
+  }
+
+  if (engine->SceneCount() == 0)
+  {
+    igndbg << "No scene has been created yet" << std::endl;
+    return nullptr;
+  }
+
+  auto scene = engine->SceneByIndex(0);
+  if (nullptr == scene)
+  {
+    ignerr << "Internal error: scene is null." << std::endl;
+    return nullptr;
+  }
+
+  if (engine->SceneCount() > 1)
+  {
+    ignwarn << "More than one scene is available. "
+      << "Using scene [" << scene->Name() << "]" << std::endl;
+  }
+
+  if (!scene->IsInitialized() || nullptr == scene->RootVisual())
+  {
+    igndbg << "Scene is not initialized yet" << std::endl;
+    return nullptr;
+  }
+
+  return scene;
+}
 }
 }
 }

src/RenderingIface_TEST.cc

@@ -19,6 +19,8 @@
 
 #include "test_config.h"  // NOLINT(build/include)
 
+#include <ignition/common/Console.hh>
+
 #include "ignition/rendering/config.hh"
 #include "ignition/rendering/RenderEngine.hh"
 #include "ignition/rendering/RenderingIface.hh"
@@ -46,7 +48,10 @@ unsigned int defaultEnginesForTest()
 /////////////////////////////////////////////////
 TEST(RenderingIfaceTest, GetEngine)
 {
+  common::Console::SetVerbosity(4);
+
   unsigned int count = defaultEnginesForTest();
+  EXPECT_GT(count, 0u);
 
   EXPECT_EQ(count, engineCount());
 
@@ -55,6 +60,7 @@ TEST(RenderingIfaceTest, GetEngine)
   EXPECT_FALSE(isEngineLoaded("ogre2"));
   EXPECT_FALSE(isEngineLoaded("optix"));
   EXPECT_FALSE(isEngineLoaded("no_such_engine"));
+  EXPECT_EQ(nullptr, sceneFromFirstRenderEngine());
 
   // check get engine
   for (unsigned int i = 0; i < count; ++i)
@@ -73,6 +79,16 @@ TEST(RenderingIfaceTest, GetEngine)
       ++i;
 #endif
 
+#ifndef _WIN32
+    // Windows CI fails with
+    // Ogre::RenderingAPIException::RenderingAPIException: OpenGL 1.5 is not
+    // supported in GLRenderSystem::initialiseContext
+    auto scene = eng->CreateScene("scene");
+    EXPECT_NE(nullptr, scene);
+
+    EXPECT_EQ(scene, sceneFromFirstRenderEngine());
+#endif
+
     ASSERT_EQ(1u, loadedEngines().size());
     EXPECT_EQ(eng->Name(), loadedEngines()[0]);
 
@@ -81,6 +97,7 @@ TEST(RenderingIfaceTest, GetEngine)
   }
 
   EXPECT_TRUE(loadedEngines().empty());
+  EXPECT_EQ(nullptr, sceneFromFirstRenderEngine());
 
   // non-existent engine
   EXPECT_EQ(nullptr, engine("no_such_engine"));
@@ -90,6 +107,8 @@ TEST(RenderingIfaceTest, GetEngine)
 /////////////////////////////////////////////////
 TEST(RenderingIfaceTest, RegisterEngine)
 {
+  common::Console::SetVerbosity(4);
+
   unsigned int count = defaultEnginesForTest();
 
   if (count == 0)