Fix segfaults in the example scene.

example-app/examplescene.cpp

@@ -22,18 +22,7 @@ ExampleScene::~ExampleScene() = default;
 
 void ExampleScene::init()
 {
-  setSkybox(new Qtk::Skybox(":/textures/skybox/right.png",
-                            ":/textures/skybox/top.png",
-                            ":/textures/skybox/front.png",
-                            ":/textures/skybox/left.png",
-                            ":/textures/skybox/bottom.png",
-                            ":/textures/skybox/back.png",
-                            "Skybox"));
-
-  std::string spartanPath = QTK_EXAMPLE_SOURCE_DIR;
-  spartanPath += "/../resources/models/spartan/spartan.obj";
-  auto spartan = addObject(new Model("spartan", spartanPath.c_str()));
-  spartan->getTransform().setTranslation(-4.0f, 0.0f, 0.0f);
+  setSkybox(new Qtk::Skybox);
 
   auto mesh = addObject(
       new Qtk::MeshRenderer("rightTriangle", Triangle(QTK_DRAW_ELEMENTS)));

resources/minimal_resources.qrc

@@ -1,6 +1,5 @@
 <RCC>
     <qresource prefix="/textures">
-        <file alias="plaster.png">images/plaster.png</file>
         <file alias="crate.png">images/crate.png</file>
         <file alias="stone.png">images/stone.png</file>
         <file alias="wood.png">images/wood.png</file>

resources/resources.qrc

@@ -1,6 +1,5 @@
 <RCC>
     <qresource prefix="/textures">
-        <file alias="plaster.png">images/plaster.png</file>
         <file alias="crate.png">images/crate.png</file>
         <file alias="stone.png">images/stone.png</file>
         <file alias="wood.png">images/wood.png</file>

src/app/qtkmainwindow.cpp

@@ -62,7 +62,7 @@ MainWindow::MainWindow(QWidget * parent) : QMainWindow(parent)
   ui_->menuView->addAction(ui_->qtk__TreeView->toggleViewAction());
 
   // Set the window icon used for Qtk.
-  setWindowIcon(Qtk::getIcon());
+  setWindowIcon(getIcon());
 }
 
 MainWindow::~MainWindow()

src/app/qtkmainwindow.h

@@ -132,6 +132,11 @@ class MainWindow : public QMainWindow
      */
     void setScene(Qtk::Scene * scene);
 
+    /**
+     * @return Default icon to use for Qtk desktop application.
+     */
+    static QIcon getIcon() { return QIcon(":/icons/icon.png"); }
+
   public slots:
     /**
      * Trigger a refresh for widgets related to a scene that has been updated.

src/app/qtkscene.cpp

@@ -426,6 +426,7 @@ void QtkScene::draw()
   // WARNING: We must call the base class draw() function first.
   // + This will handle rendering core scene components like the Skybox.
   Scene::draw();
+  const QVector3D cameraPosition = getCamera().getTransform().getTranslation();
 
   mTestPhong->bindShaders();
   mTestPhong->setUniform("uModelInverseTransposed",
@@ -433,14 +434,12 @@ void QtkScene::draw()
   mTestPhong->setUniform(
       "uLightPosition",
       MeshRenderer::getInstance("phongLight")->getTransform().getTranslation());
-  mTestPhong->setUniform("uCameraPosition",
-                         QtkScene::getCamera().getTransform().getTranslation());
+  mTestPhong->setUniform("uCameraPosition", cameraPosition);
   mTestPhong->releaseShaders();
   mTestPhong->draw();
 
   mTestAmbient->bindShaders();
-  mTestAmbient->setUniform(
-      "uCameraPosition", QtkScene::getCamera().getTransform().getTranslation());
+  mTestAmbient->setUniform("uCameraPosition", cameraPosition);
   mTestAmbient->releaseShaders();
   mTestAmbient->draw();
 
@@ -452,8 +451,7 @@ void QtkScene::draw()
                            MeshRenderer::getInstance("diffuseLight")
                                ->getTransform()
                                .getTranslation());
-  mTestDiffuse->setUniform(
-      "uCameraPosition", QtkScene::getCamera().getTransform().getTranslation());
+  mTestDiffuse->setUniform("uCameraPosition", cameraPosition);
   mTestDiffuse->releaseShaders();
   mTestDiffuse->draw();
 
@@ -465,67 +463,82 @@ void QtkScene::draw()
                             MeshRenderer::getInstance("specularLight")
                                 ->getTransform()
                                 .getTranslation());
-  mTestSpecular->setUniform(
-      "uCameraPosition", QtkScene::getCamera().getTransform().getTranslation());
+  mTestSpecular->setUniform("uCameraPosition", cameraPosition);
   mTestSpecular->releaseShaders();
   mTestSpecular->draw();
 }
 
 void QtkScene::update()
 {
-  auto mySpartan = Model::getInstance("My spartan");
-  mySpartan->getTransform().rotate(0.75f, 0.0f, 1.0f, 0.0f);
+  auto getModel = Model::getInstance;
+  const QVector3D cameraPosition = getCamera().getTransform().getTranslation();
 
-  auto myCube = MeshRenderer::getInstance("My cube");
-  myCube->getTransform().rotate(-0.75f, 0.0f, 1.0f, 0.0f);
+  // Models may have failed to load, so we should check before accessing.
+  if (auto mySpartan = getModel("My spartan"); mySpartan) {
+    mySpartan->getTransform().rotate(0.75f, 0.0f, 1.0f, 0.0f);
+  }
 
-  auto position = MeshRenderer::getInstance("alienTestLight")
-                      ->getTransform()
-                      .getTranslation();
-  auto alien = Model::getInstance("alienTest");
-  alien->setUniform("uLight.position", position);
-  alien->setUniform("uCameraPosition",
-                    QtkScene::getCamera().getTransform().getTranslation());
-  auto posMatrix = alien->getTransform().toMatrix();
-  alien->setUniform("uMVP.normalMatrix", posMatrix.normalMatrix());
-  alien->setUniform("uMVP.model", posMatrix);
-  alien->setUniform("uMVP.view", QtkScene::getCamera().toMatrix());
-  alien->setUniform("uMVP.projection", QtkScene::getProjectionMatrix());
-  alien->getTransform().rotate(0.75f, 0.0f, 1.0f, 0.0f);
+  if (auto myCube = getModel("My cube"); myCube) {
+    myCube->getTransform().rotate(-0.75f, 0.0f, 1.0f, 0.0f);
+  }
 
-  position = MeshRenderer::getInstance("spartanTestLight")
-                 ->getTransform()
-                 .getTranslation();
-  auto spartan = Model::getInstance("spartanTest");
-  spartan->setUniform("uLight.position", position);
-  spartan->setUniform("uCameraPosition",
-                      QtkScene::getCamera().getTransform().getTranslation());
-  posMatrix = spartan->getTransform().toMatrix();
-  spartan->setUniform("uMVP.normalMatrix", posMatrix.normalMatrix());
-  spartan->setUniform("uMVP.model", posMatrix);
-  spartan->setUniform("uMVP.view", QtkScene::getCamera().toMatrix());
-  spartan->setUniform("uMVP.projection", QtkScene::getProjectionMatrix());
-  spartan->getTransform().rotate(0.75f, 0.0f, 1.0f, 0.0f);
+  // Helper lambda to set the light position used by GLSL shaders on the model.
+  // TODO: This could be a helper function on the Model class.
+  auto setLightPosition = [](const std::string & lightName, Model * model) {
+    if (auto light = Model::getInstance(lightName.c_str()); light) {
+      QVector3D position = light->getTransform().getTranslation();
+      model->setUniform("uLight.position", position);
+    } else {
+      qDebug() << "[QtkScene] Failed to set light position: "
+               << lightName.c_str();
+    }
+  };
 
-  auto phong = MeshRenderer::getInstance("testPhong");
-  phong->getTransform().rotate(0.75f, 1.0f, 0.5f, 0.0f);
-  phong->bindShaders();
-  position =
-      MeshRenderer::getInstance("testLight")->getTransform().getTranslation();
-  phong->setUniform("uLight.position", position);
-  phong->setUniform("uCameraPosition",
-                    QtkScene::getCamera().getTransform().getTranslation());
-  posMatrix = phong->getTransform().toMatrix();
-  phong->setUniform("uMVP.normalMatrix", posMatrix.normalMatrix());
-  phong->setUniform("uMVP.model", posMatrix);
-  phong->setUniform("uMVP.view", QtkScene::getCamera().toMatrix());
-  phong->setUniform("uMVP.projection", QtkScene::getProjectionMatrix());
-  phong->releaseShaders();
+  QMatrix4x4 posMatrix;
+  if (auto alien = getModel("alienTest"); alien) {
+    setLightPosition("alienTestLight", alien);
+
+    alien->setUniform("uCameraPosition", cameraPosition);
+    posMatrix = alien->getTransform().toMatrix();
+    alien->setUniform("uMVP.normalMatrix", posMatrix.normalMatrix());
+    alien->setUniform("uMVP.model", posMatrix);
+    alien->setUniform("uMVP.view", QtkScene::getCamera().toMatrix());
+    alien->setUniform("uMVP.projection", QtkScene::getProjectionMatrix());
+    alien->getTransform().rotate(0.75f, 0.0f, 1.0f, 0.0f);
+  }
+
+  if (auto spartan = getModel("spartanTest"); spartan) {
+    setLightPosition("spartanTestLight", spartan);
+
+    spartan->setUniform("uCameraPosition", cameraPosition);
+    posMatrix = spartan->getTransform().toMatrix();
+    spartan->setUniform("uMVP.normalMatrix", posMatrix.normalMatrix());
+    spartan->setUniform("uMVP.model", posMatrix);
+    spartan->setUniform("uMVP.view", QtkScene::getCamera().toMatrix());
+    spartan->setUniform("uMVP.projection", QtkScene::getProjectionMatrix());
+    spartan->getTransform().rotate(0.75f, 0.0f, 1.0f, 0.0f);
+  }
+
+  if (auto phong = getModel("testPhong"); phong) {
+    setLightPosition("testLight", phong);
+
+    phong->getTransform().rotate(0.75f, 1.0f, 0.5f, 0.0f);
+    phong->bindShaders();
+    phong->setUniform("uCameraPosition", cameraPosition);
+    posMatrix = phong->getTransform().toMatrix();
+    phong->setUniform("uMVP.normalMatrix", posMatrix.normalMatrix());
+    phong->setUniform("uMVP.model", posMatrix);
+    phong->setUniform("uMVP.view", QtkScene::getCamera().toMatrix());
+    phong->setUniform("uMVP.projection", QtkScene::getProjectionMatrix());
+    phong->releaseShaders();
+  }
+
+  // MeshRenderers are lower level opengl objects baked into the source code.
+  auto getMesh = MeshRenderer::getInstance;
 
   // Rotate lighting example cubes
   mTestPhong->getTransform().rotate(0.75f, 0.5f, 0.3f, 0.2f);
-  MeshRenderer::getInstance("noLight")->getTransform().rotate(
-      0.75f, 0.5f, 0.3f, 0.2f);
+  getMesh("noLight")->getTransform().rotate(0.75f, 0.5f, 0.3f, 0.2f);
   mTestAmbient->getTransform().rotate(0.75f, 0.5f, 0.3f, 0.2f);
   mTestDiffuse->getTransform().rotate(0.75f, 0.5f, 0.3f, 0.2f);
   mTestSpecular->getTransform().rotate(0.75f, 0.5f, 0.3f, 0.2f);
@@ -533,46 +546,27 @@ void QtkScene::update()
   // Examples of various translations and rotations
 
   // Rotate in multiple directions simultaneously
-  MeshRenderer::getInstance("rgbNormalsCube")
-      ->getTransform()
-      .rotate(0.75f, 0.2f, 0.4f, 0.6f);
+  getMesh("rgbNormalsCube")->getTransform().rotate(0.75f, 0.2f, 0.4f, 0.6f);
 
   // Pitch forward and roll sideways
-  MeshRenderer::getInstance("leftTriangle")
-      ->getTransform()
-      .rotate(0.75f, 1.0f, 0.0f, 0.0f);
-  MeshRenderer::getInstance("rightTriangle")
-      ->getTransform()
-      .rotate(0.75f, 0.0f, 0.0f, 1.0f);
+  getMesh("leftTriangle")->getTransform().rotate(0.75f, 1.0f, 0.0f, 0.0f);
+  getMesh("rightTriangle")->getTransform().rotate(0.75f, 0.0f, 0.0f, 1.0f);
 
   // Move between two positions over time
   static float translateX = 0.025f;
   float limit = -9.0f;  // Origin position.x - 2.0f
-  float posX = MeshRenderer::getInstance("topTriangle")
-                   ->getTransform()
-                   .getTranslation()
-                   .x();
+  float posX = getMesh("topTriangle")->getTransform().getTranslation().x();
   if (posX < limit || posX > limit + 4.0f) {
     translateX = -translateX;
   }
-  MeshRenderer::getInstance("topTriangle")
-      ->getTransform()
-      .translate(translateX, 0.0f, 0.0f);
-  MeshRenderer::getInstance("bottomTriangle")
-      ->getTransform()
-      .translate(-translateX, 0.0f, 0.0f);
+  getMesh("topTriangle")->getTransform().translate(translateX, 0.0f, 0.0f);
+  getMesh("bottomTriangle")->getTransform().translate(-translateX, 0.0f, 0.0f);
   // And lets rotate the triangles in two directions at once
-  MeshRenderer::getInstance("topTriangle")
-      ->getTransform()
-      .rotate(0.75f, 0.2f, 0.0f, 0.4f);
-  MeshRenderer::getInstance("bottomTriangle")
-      ->getTransform()
-      .rotate(0.75f, 0.0f, 0.2f, 0.4f);
+  getMesh("topTriangle")->getTransform().rotate(0.75f, 0.2f, 0.0f, 0.4f);
+  getMesh("bottomTriangle")->getTransform().rotate(0.75f, 0.0f, 0.2f, 0.4f);
   // And make the bottom triangle green, instead of RGB
 
   // Rotate center cube in several directions simultaneously
   // + Not subject to gimbal lock since we are using quaternions :)
-  MeshRenderer::getInstance("centerCube")
-      ->getTransform()
-      .rotate(0.75f, 0.2f, 0.4f, 0.6f);
+  getMesh("centerCube")->getTransform().rotate(0.75f, 0.2f, 0.4f, 0.6f);
 }

src/designer-plugins/widgetplugin.cpp

@@ -67,7 +67,7 @@ QString WidgetPlugin::whatsThis() const
 
 QIcon WidgetPlugin::icon() const
 {
-  return Qtk::getIcon();
+  return QIcon(":/icons/icon.png");
 }
 
 bool WidgetPlugin::isContainer() const

src/qtk/meshrenderer.cpp

@@ -121,9 +121,7 @@ void MeshRenderer::draw()
   bindShaders();
   mVAO.bind();
 
-  if (mTexture.hasTexture()) {
-    mTexture.getOpenGLTexture().bind();
-  }
+  mTexture.bind();
 
   // TODO: Automate uniforms some other way
   setUniformMVP();
@@ -138,9 +136,7 @@ void MeshRenderer::draw()
                    mShape.mIndices.data());
   }
 
-  if (mTexture.hasTexture()) {
-    mTexture.getOpenGLTexture().release();
-  }
+  mTexture.bind();
 
   mVAO.release();
   releaseShaders();

src/qtk/qtkapi.h

@@ -43,14 +43,6 @@ namespace Qtk
     }
     return widget;
   }
-
-  /**
-   * @return Default icon to use for Qtk desktop application.
-   */
-  static QIcon getIcon()
-  {
-    return QIcon(":/icons/icon.png");
-  }
 }  // namespace Qtk
 
 #endif  // QTK_QTKAPI_H

src/qtk/skybox.cpp

@@ -17,9 +17,28 @@ using namespace Qtk;
  * Constructors / Destructors
  ******************************************************************************/
 
-Skybox::Skybox(QOpenGLTexture * cubeMap, const std::string & name)
+Skybox::Skybox(const std::string & name) :
+    mVBO(QOpenGLBuffer::VertexBuffer),
+    mVertices(Cube(QTK_DRAW_ELEMENTS).getVertices()),
+    mIndices(Cube(QTK_DRAW_ELEMENTS).getIndexData())
 {
-  mTexture.setTexture(cubeMap);
+  QImage image({1024, 1024}, QImage::Format_RGBA8888);
+  image.fill(Qt::darkGray);
+  mTexture.setCubeMap(image, image, image, image, image, image);
+  init();
+}
+
+Skybox::Skybox(QOpenGLTexture * cubeMap, const std::string & name) :
+    mVBO(QOpenGLBuffer::VertexBuffer),
+    mVertices(Cube(QTK_DRAW_ELEMENTS).getVertices()),
+    mIndices(Cube(QTK_DRAW_ELEMENTS).getIndexData())
+{
+  if (cubeMap == Q_NULLPTR) {
+    qDebug()
+        << "[Qtk] Failed to set cubemap for skybox with null QOpenGLTexture.";
+  } else {
+    mTexture.setTexture(cubeMap);
+  }
   init();
 }
 
@@ -34,13 +53,13 @@ Skybox::Skybox(const std::string & right,
     mVertices(Cube(QTK_DRAW_ELEMENTS).getVertices()),
     mIndices(Cube(QTK_DRAW_ELEMENTS).getIndexData())
 {
-  init();
   mTexture.setCubeMap(QImage(right.c_str()).mirrored(),
                       QImage(top.c_str()),
                       QImage(front.c_str()),
                       QImage(left.c_str()),
                       QImage(bottom.c_str()),
                       QImage(back.c_str()));
+  init();
 }
 
 /*******************************************************************************
@@ -54,7 +73,7 @@ void Skybox::draw()
 
   mVAO.bind();
   mProgram.bind();
-  mTexture.getOpenGLTexture().bind();
+  mTexture.bind();
 
   mProgram.setUniformValue("uProjectionMatrix", Scene::getProjectionMatrix());
   mProgram.setUniformValue("uViewMatrix", Scene::getCamera().toMatrix());
@@ -62,7 +81,7 @@ void Skybox::draw()
   glDrawElements(
       GL_TRIANGLES, mIndices.size(), GL_UNSIGNED_INT, mIndices.data());
 
-  mTexture.getOpenGLTexture().bind();
+  mTexture.bind();
   mProgram.release();
   mVAO.release();
 

src/qtk/skybox.h

@@ -34,7 +34,12 @@ namespace Qtk
        * Constructors / Destructors
        ************************************************************************/
 
-      // Delegate this constructor to use default skybox images
+      /**
+       * Construct a skybox with a default texture.
+       *
+       * @param name The objectName to use for the Skybox.
+       */
+      explicit Skybox(const std::string & name = "Skybox");
 
       /**
        * Construct a skybox with an existing QOpenGLTexture.

src/qtk/texture.cpp

@@ -8,6 +8,7 @@
 
 #include <QDebug>
 #include <QImageReader>
+#include <QPainter>
 
 #include "texture.h"
 
@@ -65,6 +66,22 @@ QOpenGLTexture * OpenGLTextureFactory::initCubeMap(const char * right,
                      QImage(back));
 }
 
+QImage OpenGLTextureFactory::defaultTexture()
+{
+  QImage image({256, 256}, QImage::Format_RGBA8888);
+  image.fill(Qt::lightGray);
+
+  // Draw a red '?' to the center of the image.
+  QPainter painter(&image);
+  painter.setRenderHint(QPainter::Antialiasing);
+  painter.setPen(Qt::red);
+  painter.setFont({"Helvetica", 100, QFont::Bold});
+  constexpr QRect rect(0, 0, 256, 256);
+  painter.drawText(rect, Qt::AlignCenter, "?");
+
+  return image;
+}
+
 QOpenGLTexture * OpenGLTextureFactory::initCubeMap(const QImage & right,
                                                    const QImage & top,
                                                    const QImage & front,
@@ -87,9 +104,9 @@ QOpenGLTexture * OpenGLTextureFactory::initCubeMap(const QImage & right,
       QOpenGLTexture::CubeMapNegativeZ};
   int i = 0;
   for (const auto & face : faces) {
-    QImage faceImage(faceTextures[i]);
+    QImage & faceImage = faceTextures[i];
     if (faceImage.isNull()) {
-      qDebug() << "Error loading cube map image\n";
+      qDebug() << "[libqtk] Error loading cube map image\n";
       faceImage = defaultTexture();
     }
     faceImage = faceImage.convertToFormat(QImage::Format_RGBA8888);

src/qtk/texture.h

@@ -145,13 +145,7 @@ namespace Qtk
                                           const char * back);
 
       /// The texture used in place of a missing texture.
-      static QImage defaultTexture()
-      {
-        // Use plaster for default texture if image fails to load.
-        // This prevents segfaults when loading a texture that doesn't exist.
-        // TODO: Replace with a '?' texture to indicate missing texture.
-        return QImage(":/textures/plaster.png");
-      }
+      static QImage defaultTexture();
 
     private:
       // Private ctor to prevent creating instances of this class
@@ -223,6 +217,20 @@ namespace Qtk
         return mOpenGLTexture != Q_NULLPTR;
       }
 
+      /**
+       * Bind the OpenGL texture if it exists, avoiding segmentation faults.
+       */
+      bool bind() const
+      {
+        if (hasTexture()) {
+          // TODO: It would be nice to warn here but some objects may not have
+          // a texture. Factor Texture out of those objects so we don't bind.
+          mOpenGLTexture->bind();
+          return true;
+        }
+        return false;
+      }
+
       /*************************************************************************
        * Accessors
        ************************************************************************/
@@ -306,12 +314,12 @@ namespace Qtk
       /**
        * Sets this Texture to be a cube map with provided sides.
        *
-       * @param right Path to texture to use for right cube map side.
-       * @param top Path to texture to use for top cube map side.
-       * @param front Path to texture to use for front cube map side.
-       * @param left Path to texture to use for left cube map side.
-       * @param bottom Path to texture to use for bottom cube map side.
-       * @param back Path to texture to use for back cube map side.
+       * @param right QImage texture to use for right cube map side.
+       * @param top QImage texture to use for top cube map side.
+       * @param front QImage texture to use for front cube map side.
+       * @param left QImage texture to use for left cube map side.
+       * @param bottom QImage texture to use for bottom cube map side.
+       * @param back QImage texture to use for back cube map side.
        */
       virtual inline void setCubeMap(const QImage & right,
                                      const QImage & top,