Make games launch faster by loading resources in the background (#5572)

* Only the first scene and global objects resources (images, sounds, 3D models etc...) will be downloaded during launch of the game. This usually allows for a very fast loading time.
* Other scenes resources will continue to load in the background. It has no impact on the game performance as this is done on other threads by the browser or the engine running the game.
* Scenes are loaded in the order they are listed in the project manager.
* You can also use actions and expressions to prioritize a scene (if it's known that a level will be needed soon for example) or read the current loading progress. This allows to create lightweight scenes that can act as custom loading screens. Otherwise, the launch loading screen will be shown if a scene is still loading when launched.
* Read more about this on https://wiki.gdevelop.io/gdevelop5/all-features/resources-loading/.

Core/GDCore/Extensions/Builtin/SceneExtension.cpp

@@ -5,6 +5,7 @@
  */
 #include "AllBuiltinExtensions.h"
 #include "GDCore/Tools/Localization.h"
+#include "GDCore/Extensions/Metadata/MultipleInstructionMetadata.h"
 
 using namespace std;
 namespace gd {
@@ -57,7 +58,7 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsSceneExtension(
   extension
       .AddCondition("DoesSceneExist",
                     _("Does scene exist"),
-                    _("Check if scene exists."),
+                    _("Check if a scene exists."),
                     _("Scene _PARAM1_ exists"),
                     "",
                     "res/actions/texte.png",
@@ -163,6 +164,45 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsSceneExtension(
           "res/actions/window.png")
       .SetHelpPath("/interface/scene-editor/events")
       .AddCodeOnlyParameter("currentScene", "");
+
+  extension
+      .AddAction("PrioritizeLoadingOfScene",
+                 _("Preload scene"),
+                 _("Preload a scene resources as soon as possible in background."),
+                 _("Preload scene _PARAM1_ in background"),
+                 "",
+                 "res/actions/replaceScene24.png",
+                 "res/actions/replaceScene.png")
+      .SetHelpPath("/all-features/resources-loading")
+      .AddCodeOnlyParameter("currentScene", "")
+      .AddParameter("sceneName", _("Name of the new scene"))
+      .MarkAsAdvanced();
+
+  extension.AddExpressionAndCondition("number",
+                                "SceneLoadingProgress",
+                                _("Scene loading progress"),
+                                _("The progress of resources loading in background for a scene (between 0 and 1)."),
+                                _("_PARAM0_ loading progress"),
+                                _(""),
+                                "res/actions/replaceScene24.png")
+      .SetHelpPath("/all-features/resources-loading")
+      .AddCodeOnlyParameter("currentScene", "")
+      .AddParameter("sceneName", _("Scene name"))
+      .UseStandardParameters("number", ParameterOptions::MakeNewOptions())
+      .MarkAsAdvanced();
+
+  extension
+      .AddCondition("AreSceneAssetsLoaded",
+                    _("Scene preloaded"),
+                    _("Check if scene resources have finished to load in background."),
+                    _("Scene _PARAM1_ was preloaded in background"),
+                    "",
+                    "res/actions/replaceScene24.png",
+                    "res/actions/replaceScene.png")
+      .SetHelpPath("/all-features/resources-loading")
+      .AddCodeOnlyParameter("currentScene", "")
+      .AddParameter("sceneName", _("Scene name"))
+      .MarkAsAdvanced();
 }
 
 }  // namespace gd

Core/GDCore/Extensions/Metadata/MultipleInstructionMetadata.h

@@ -191,6 +191,16 @@ class GD_CORE_API MultipleInstructionMetadata : public AbstractFunctionMetadata
     return *this;
   }
 
+  /**
+   * \see gd::InstructionMetadata::SetHelpPath
+   */
+  MultipleInstructionMetadata &SetHelpPath(const gd::String &path) {
+    if (expression) expression->SetHelpPath(path);
+    if (condition) condition->SetHelpPath(path);
+    if (action) action->SetHelpPath(path);
+    return *this;
+  }
+
   /**
    * \see gd::InstructionMetadata::MarkAsSimple
    */

Core/GDCore/IDE/DependenciesAnalyzer.cpp

@@ -4,7 +4,6 @@
  * reserved. This project is released under the MIT License.
  */
 
-#if defined(GD_IDE_ONLY)
 #include "DependenciesAnalyzer.h"
 #include <algorithm>
 #include "GDCore/Events/Builtin/LinkEvent.h"
@@ -29,9 +28,9 @@ DependenciesAnalyzer::DependenciesAnalyzer(const gd::Project& project_,
 
 bool DependenciesAnalyzer::Analyze() {
   if (layout)
-    return Analyze(layout->GetEvents(), true);
+    return Analyze(layout->GetEvents());
   else if (externalEvents)
-    return Analyze(externalEvents->GetEvents(), true);
+    return Analyze(externalEvents->GetEvents());
 
   std::cout << "ERROR: DependenciesAnalyzer called without any layout or "
                "external events.";
@@ -40,63 +39,38 @@ bool DependenciesAnalyzer::Analyze() {
 
 DependenciesAnalyzer::~DependenciesAnalyzer() {}
 
-bool DependenciesAnalyzer::Analyze(const gd::EventsList& events, bool isOnTopLevel) {
+bool DependenciesAnalyzer::Analyze(const gd::EventsList& events) {
   for (unsigned int i = 0; i < events.size(); ++i) {
     const gd::LinkEvent* linkEvent = dynamic_cast<const gd::LinkEvent*>(&events[i]);
     if (linkEvent) {
-      DependenciesAnalyzer analyzer(*this);
-
       gd::String linked = linkEvent->GetTarget();
       if (project.HasExternalEventsNamed(linked)) {
         if (std::find(parentExternalEvents.begin(),
                       parentExternalEvents.end(),
-                      linked) != parentExternalEvents.end())
-          return false;  // Circular dependency!
-
-        externalEventsDependencies.insert(
-            linked);  // There is a direct dependency
-        if (!isOnTopLevel) notTopLevelExternalEventsDependencies.insert(linked);
-        analyzer.AddParentExternalEvents(linked);
-        if (!analyzer.Analyze(project.GetExternalEvents(linked).GetEvents(),
-                              isOnTopLevel))
+                      linked) != parentExternalEvents.end()) {
+          // Circular dependency!
           return false;
-
+        }
+        bool wasDependencyJustAdded = externalEventsDependencies.insert(linked).second;
+        if (wasDependencyJustAdded) {
+          parentExternalEvents.push_back(linked);
+          if (!Analyze(project.GetExternalEvents(linked).GetEvents()))
+            return false;
+          parentExternalEvents.pop_back();
+        }
       } else if (project.HasLayoutNamed(linked)) {
         if (std::find(parentScenes.begin(), parentScenes.end(), linked) !=
-            parentScenes.end())
-          return false;  // Circular dependency!
-
-        scenesDependencies.insert(linked);  // There is a direct dependency
-        if (!isOnTopLevel) notTopLevelScenesDependencies.insert(linked);
-        analyzer.AddParentScene(linked);
-        if (!analyzer.Analyze(project.GetLayout(linked).GetEvents(),
-                              isOnTopLevel))
+            parentScenes.end()) {
+          // Circular dependency!
           return false;
-      }
-
-      // Update with indirect dependencies.
-      scenesDependencies.insert(analyzer.GetScenesDependencies().begin(),
-                                analyzer.GetScenesDependencies().end());
-      externalEventsDependencies.insert(
-          analyzer.GetExternalEventsDependencies().begin(),
-          analyzer.GetExternalEventsDependencies().end());
-      sourceFilesDependencies.insert(
-          analyzer.GetSourceFilesDependencies().begin(),
-          analyzer.GetSourceFilesDependencies().end());
-      notTopLevelScenesDependencies.insert(
-          analyzer.GetNotTopLevelScenesDependencies().begin(),
-          analyzer.GetNotTopLevelScenesDependencies().end());
-      notTopLevelExternalEventsDependencies.insert(
-          analyzer.GetNotTopLevelExternalEventsDependencies().begin(),
-          analyzer.GetNotTopLevelExternalEventsDependencies().end());
-
-      if (!isOnTopLevel) {
-        notTopLevelScenesDependencies.insert(
-            analyzer.GetScenesDependencies().begin(),
-            analyzer.GetScenesDependencies().end());
-        notTopLevelExternalEventsDependencies.insert(
-            analyzer.GetExternalEventsDependencies().begin(),
-            analyzer.GetExternalEventsDependencies().end());
+        }
+        bool wasDependencyJustAdded = scenesDependencies.insert(linked).second;
+        if (wasDependencyJustAdded) {
+          parentScenes.push_back(linked);
+          if (!Analyze(project.GetLayout(linked).GetEvents()))
+            return false;
+          parentScenes.pop_back();
+        }
       }
     }
 
@@ -112,45 +86,9 @@ bool DependenciesAnalyzer::Analyze(const gd::EventsList& events, bool isOnTopLev
 
     // Analyze sub events dependencies
     if (events[i].CanHaveSubEvents()) {
-      if (!Analyze(events[i].GetSubEvents(), false)) return false;
+      if (!Analyze(events[i].GetSubEvents())) return false;
     }
   }
 
   return true;
 }
-
-gd::String DependenciesAnalyzer::ExternalEventsCanBeCompiledForAScene() {
-  if (!externalEvents) {
-    std::cout << "ERROR: ExternalEventsCanBeCompiledForAScene called without "
-                 "external events set!"
-              << std::endl;
-    return "";
-  }
-
-  gd::String sceneName;
-  for (unsigned int i = 0; i < project.GetLayoutsCount(); ++i) {
-    // For each layout, compute the dependencies and the dependencies which are
-    // not coming from a top level event.
-    DependenciesAnalyzer analyzer(project, project.GetLayout(i));
-    if (!analyzer.Analyze()) continue;  // Analyze failed -> Cyclic dependencies
-    const std::set<gd::String>& dependencies =
-        analyzer.GetExternalEventsDependencies();
-    const std::set<gd::String>& notTopLevelDependencies =
-        analyzer.GetNotTopLevelExternalEventsDependencies();
-
-    // Check if the external events is a dependency, and that is is only present
-    // as a link on the top level.
-    if (dependencies.find(externalEvents->GetName()) != dependencies.end() &&
-        notTopLevelDependencies.find(externalEvents->GetName()) ==
-            notTopLevelDependencies.end()) {
-      if (!sceneName.empty())
-        return "";  // External events can be compiled only if one scene is
-                    // including them.
-      else
-        sceneName = project.GetLayout(i).GetName();
-    }
-  }
-
-  return sceneName;  // External events can be compiled and used for the scene.
-}
-#endif

Core/GDCore/IDE/DependenciesAnalyzer.h

@@ -39,11 +39,6 @@ class GD_CORE_API DependenciesAnalyzer {
 
   /**
    * \brief Constructor for analyzing the dependencies of external events.
-   *
-   * You can also call then
-   * DependenciesAnalyzer::ExternalEventsCanBeCompiledForAScene to check if the
-   * external events can be compiled separately and called by a scene. \see
-   * DependenciesAnalyzer::ExternalEventsCanBeCompiledForAScene
    */
   DependenciesAnalyzer(const gd::Project& project_,
                        const gd::ExternalEvents& externalEvents);
@@ -60,18 +55,6 @@ class GD_CORE_API DependenciesAnalyzer {
    */
   bool Analyze();
 
-  /**
-   * Check if the external events (passed in the constructor) can be compiled
-   * and called by a single scene:<br> This is possible when the link calling
-   * the external events does not have any parent event and when this situation
-   * occurs only in a single scene and not in another.
-   *
-   * \return The name of the scene which is able to call the compiled external
-   * events. If empty, no scene is able to call them. (So external events have
-   * to be included directly by links).
-   */
-  gd::String ExternalEventsCanBeCompiledForAScene();
-
   /**
    * \brief Return the scenes being dependencies of the scene or external events
    * passed in the constructor.
@@ -96,25 +79,6 @@ class GD_CORE_API DependenciesAnalyzer {
     return sourceFilesDependencies;
   };
 
-  /**
-   * \brief Return the scenes being dependencies of the scene or external events
-   * passed in the constructor, but being not top level dependencies: The links
-   * including them are not a top level events (i.e: They have a parent event).
-   */
-  const std::set<gd::String>& GetNotTopLevelScenesDependencies() const {
-    return notTopLevelScenesDependencies;
-  };
-
-  /**
-   * \brief Return the external events being dependencies of the scene or
-   * external events passed in the constructor, but being not top level
-   * dependencies: The links including them are not a top level events (i.e:
-   * They have a parent event).
-   */
-  const std::set<gd::String>& GetNotTopLevelExternalEventsDependencies() const {
-    return notTopLevelExternalEventsDependencies;
-  };
-
  private:
   /**
    * \brief Analyze the dependencies of the events.
@@ -124,32 +88,11 @@ class GD_CORE_API DependenciesAnalyzer {
    * (they have no parents). \return false if a circular dependency exists, true
    * otherwise.
    */
-  bool Analyze(const gd::EventsList& events, bool isOnTopLevel);
-
-  void AddParentScene(gd::String parentScene) {
-    parentScenes.push_back(parentScene);
-  };
-  void AddParentExternalEvents(gd::String parentExternalEvents_) {
-    parentExternalEvents.push_back(parentExternalEvents_);
-  };
-
-  /**
-   * Return true if all links pointing to external events called \a
-   * externalEventsName are only at the top level of \a events. The function
-   * return false as soon as it discover a link to external events which is not
-   * at the top level ( i.e: It has a parent event ).
-   *
-   * \warning The function assumes that there are not cyclic dependencies.
-   */
-  bool CheckIfExternalEventsIsLinkedOnlyAtTopLevel(
-      const gd::String& externalEventsName,
-      std::vector<std::shared_ptr<gd::BaseEvent> >& events);
+  bool Analyze(const gd::EventsList& events);
 
   std::set<gd::String> scenesDependencies;
   std::set<gd::String> externalEventsDependencies;
   std::set<gd::String> sourceFilesDependencies;
-  std::set<gd::String> notTopLevelScenesDependencies;
-  std::set<gd::String> notTopLevelExternalEventsDependencies;
   std::vector<gd::String>
       parentScenes;  ///< Used to check for circular dependencies.
   std::vector<gd::String>

Core/GDCore/IDE/Events/EventsIdentifiersFinder.cpp

@@ -226,7 +226,7 @@ void EventsIdentifiersFinder::FindArgumentsInEventsAndDependencies(
   eventWorker.Launch(layout.GetEvents(),
       gd::ProjectScopedContainers::MakeNewProjectScopedContainersForProjectAndLayout(project, layout));
 
-  DependenciesAnalyzer dependenciesAnalyzer = DependenciesAnalyzer(project, layout);
+  DependenciesAnalyzer dependenciesAnalyzer(project, layout);
   dependenciesAnalyzer.Analyze();
   for (const gd::String& externalEventName : dependenciesAnalyzer.GetExternalEventsDependencies()) {
     const gd::ExternalEvents& externalEvents = project.GetExternalEvents(externalEventName);

Core/GDCore/IDE/Events/EventsVariablesFinder.cpp

@@ -258,7 +258,7 @@ void EventsVariablesFinder::FindArgumentsInEventsAndDependencies(
   eventWorker.Launch(layout.GetEvents(),
       gd::ProjectScopedContainers::MakeNewProjectScopedContainersForProjectAndLayout(project, layout));
 
-  DependenciesAnalyzer dependenciesAnalyzer = DependenciesAnalyzer(project, layout);
+  DependenciesAnalyzer dependenciesAnalyzer(project, layout);
   dependenciesAnalyzer.Analyze();
   for (const gd::String& externalEventName : dependenciesAnalyzer.GetExternalEventsDependencies()) {
     const gd::ExternalEvents& externalEvents = project.GetExternalEvents(externalEventName);

Core/GDCore/IDE/Project/ArbitraryResourceWorker.cpp

@@ -262,13 +262,6 @@ bool ResourceWorkerInEventsWorker::DoVisitInstruction(gd::Instruction& instructi
   return false;
 };
 
-void LaunchResourceWorkerOnEvents(const gd::Project& project,
-                                  gd::EventsList& events,
-                                  gd::ArbitraryResourceWorker& worker) {
-  gd::ResourceWorkerInEventsWorker eventsWorker(project, worker);
-  eventsWorker.Launch(events);
-}
-
 gd::ResourceWorkerInEventsWorker
 GetResourceWorkerOnEvents(const gd::Project &project,
                           gd::ArbitraryResourceWorker &worker) {

Core/GDCore/IDE/Project/ArbitraryResourceWorker.h

@@ -37,7 +37,7 @@ namespace gd {
  * \see ResourcesMergingHelper
  * \see gd::ResourcesInUseHelper
  *
- * \see gd::LaunchResourceWorkerOnEvents
+ * \see gd::GetResourceWorkerOnEvents
  *
  * \ingroup IDE
  */

Core/GDCore/IDE/Project/SceneResourcesFinder.cpp

@@ -0,0 +1,35 @@
+/*
+ * GDevelop JS Platform
+ * Copyright 2008-2023 Florian Rival ([email protected]). All rights
+ * reserved. This project is released under the MIT License.
+ */
+#include "SceneResourcesFinder.h"
+
+#include "GDCore/IDE/ResourceExposer.h"
+#include "GDCore/Project/Layout.h"
+#include "GDCore/Project/Project.h"
+#include "GDCore/Serialization/SerializerElement.h"
+
+namespace gd {
+
+std::set<gd::String> SceneResourcesFinder::FindProjectResources(gd::Project &project) {
+  gd::SceneResourcesFinder resourceWorker;
+  gd::ResourceExposer::ExposeProjectResources(project, resourceWorker);
+  return resourceWorker.resourceNames;
+}
+
+std::set<gd::String> SceneResourcesFinder::FindSceneResources(gd::Project &project,
+    gd::Layout &layout) {
+  gd::SceneResourcesFinder resourceWorker;
+  gd::ResourceExposer::ExposeLayoutResources(project, layout, resourceWorker);
+  return resourceWorker.resourceNames;
+}
+
+void SceneResourcesFinder::AddUsedResource(gd::String &resourceName) {
+  if (resourceName.empty()) {
+    return;
+  }
+  resourceNames.insert(resourceName);
+}
+
+} // namespace gd