Clean up separation between plugins and app.

README.md

@@ -3,8 +3,7 @@
 [![All Builds](https://github.com/shaunrd0/qtk/actions/workflows/all-builds.yml/badge.svg)](https://github.com/shaunrd0/qtk/actions/workflows/all-builds.yml)
 [![Linting](https://github.com/shaunrd0/qtk/actions/workflows/linting.yml/badge.svg)](https://github.com/shaunrd0/qtk/actions/workflows/linting.yml)
 
-Qtk is a Qt OpenGL graphics library created primarily for my own learning
-purposes. The library wraps some QOpenGL functionality in convenience classes
+Qtk is a Qt OpenGL graphics library that wraps some QOpenGL functionality in convenience classes
 that allow rendering geometry in 2D and 3D using custom GLSL shader programs.
 
 The Qtk desktop application provides a model loader using [Assimp](https://assimp.org/) within a Qt widget application.

src/app/qtkmainwindow.cpp

@@ -9,8 +9,6 @@
 #include "qtkmainwindow.h"
 #include "ui_qtkmainwindow.h"
 
-MainWindow * MainWindow::mainWindow_ = Q_NULLPTR;
-
 /*******************************************************************************
  * Constructors / Destructors
  ******************************************************************************/
@@ -27,6 +25,10 @@ MainWindow::MainWindow(QWidget * parent) : QMainWindow(parent)
   // Initialize static container for all active QtkWidgets
   auto qtkWidgets = findChildren<Qtk::QtkWidget *>();
   for (auto & qtkWidget : qtkWidgets) {
+    // NOTE: Set a temporary scene for the widget to use for initialization.
+    // This should be replaced by loading a scene, or creating a new (unsaved)
+    // scene when Qtk is opened.
+    qtkWidget->setScene(new EmptyScene);
     views_.emplace(qtkWidget->getScene()->getSceneName(), qtkWidget);
 
     // Add GUI 'view' toolbar option to show debug console.
@@ -36,8 +38,7 @@ MainWindow::MainWindow(QWidget * parent) : QMainWindow(parent)
             &Qtk::Scene::sceneUpdated,
             this,
             &MainWindow::refreshScene);
-    connect(qtkWidget,
-            &Qtk::QtkWidget::objectFocusChanged,
+    connect(qtkWidget, &Qtk::QtkWidget::objectFocusChanged,
             ui_->qtk__ToolBox,
             &Qtk::ToolBox::updateFocus);
   }
@@ -70,10 +71,8 @@ MainWindow::~MainWindow()
 
 MainWindow * MainWindow::getMainWindow()
 {
-  if (mainWindow_ == Q_NULLPTR) {
-    mainWindow_ = new MainWindow;
-  }
-  return mainWindow_;
+  static MainWindow window;
+  return &window;
 }
 
 Qtk::QtkWidget * MainWindow::getQtkWidget(int64_t index)

src/app/qtkmainwindow.h

@@ -22,6 +22,38 @@ namespace Ui
   class MainWindow;
 }
 
+/**
+ * An empty scene used for initializing all QtkWidgets within the MainWindow.
+ * This serves as a temporary placeholder for QtkScene (for example), which is
+ * defined in the separate qtk_gui target. The reason for this separation is to
+ * support the use of QtkWidgets (the qtk_plugins target) within the Qt Designer
+ * application without implementations provided in the Qtk Desktop Application.
+ *
+ * For the Qtk application, this should be replaced by loading the previous
+ * scene or creating a new _unsaved_ scene when the application is opened.
+ * Currently we have essentially hard-coded QtkScene to use as examples for
+ * testing the application. This means that the only way to create or modify a
+ * scene is to write code. Any modifications made in the application, such as
+ * moving or resizing objects, will not persist and cannot be saved.
+ *
+ * For users of Qtk Designer Plugins, this means that installing
+ * the `qtk_plugins` target to Qt Designer allows use all of the designer's
+ * features to build an interface and position or resize a QtkWidget as needed.
+ * The QtkWidget also appears as widget in the IDE's toolbars and can be added
+ * to any new application easily, once the plugins are installed.
+ *
+ * Once the application is designed, you can define a custom scene and use the
+ * Qtk API or Qt OpenGL funtions directly to render to it.
+ *
+ * Any application using a QtkWidget can set a custom scene in their main
+ * function. See the MainWindow::MainWindow constructor as an example.
+ */
+class EmptyScene : public Qtk::Scene {
+  void init() override {
+    setSceneName("Empty Scene");
+  }
+};
+
 /**
  * MainWindow class to provide an example of using a QtkWidget within a Qt
  * window application.
@@ -82,7 +114,6 @@ class MainWindow : public QMainWindow
     MainWindow(const MainWindow &) {};
 
     Ui::MainWindow * ui_ {};
-    static MainWindow * mainWindow_;
 
     /**
      * Maps a scene name to the QtkWidget viewing it.