Fix segfaults in the example scene.

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",
+  mTestPhong->setUniform("uCameraPosition", cameraPosition);
-                         QtkScene::getCamera().getTransform().getTranslation());
   mTestPhong->releaseShaders();
   mTestPhong->draw();
 
   mTestAmbient->bindShaders();
-  mTestAmbient->setUniform(
+  mTestAmbient->setUniform("uCameraPosition", cameraPosition);
-      "uCameraPosition", QtkScene::getCamera().getTransform().getTranslation());
   mTestAmbient->releaseShaders();
   mTestAmbient->draw();
 
@@ -452,8 +451,7 @@ void QtkScene::draw()
                            MeshRenderer::getInstance("diffuseLight")
                                ->getTransform()
                                .getTranslation());
-  mTestDiffuse->setUniform(
+  mTestDiffuse->setUniform("uCameraPosition", cameraPosition);
-      "uCameraPosition", QtkScene::getCamera().getTransform().getTranslation());
   mTestDiffuse->releaseShaders();
   mTestDiffuse->draw();
 
@@ -465,67 +463,82 @@ void QtkScene::draw()
                             MeshRenderer::getInstance("specularLight")
                                 ->getTransform()
                                 .getTranslation());
-  mTestSpecular->setUniform(
+  mTestSpecular->setUniform("uCameraPosition", cameraPosition);
-      "uCameraPosition", QtkScene::getCamera().getTransform().getTranslation());
   mTestSpecular->releaseShaders();
   mTestSpecular->draw();
 }
 
 void QtkScene::update()
 {
-  auto mySpartan = Model::getInstance("My spartan");
+  auto getModel = Model::getInstance;
+  const QVector3D cameraPosition = getCamera().getTransform().getTranslation();
+
+  // 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 myCube = MeshRenderer::getInstance("My cube");
+  if (auto myCube = getModel("My cube"); myCube) {
     myCube->getTransform().rotate(-0.75f, 0.0f, 1.0f, 0.0f);
+  }
 
-  auto position = MeshRenderer::getInstance("alienTestLight")
+  // Helper lambda to set the light position used by GLSL shaders on the model.
-                      ->getTransform()
+  // TODO: This could be a helper function on the Model class.
-                      .getTranslation();
+  auto setLightPosition = [](const std::string & lightName, Model * model) {
-  auto alien = Model::getInstance("alienTest");
+    if (auto light = Model::getInstance(lightName.c_str()); light) {
-  alien->setUniform("uLight.position", position);
+      QVector3D position = light->getTransform().getTranslation();
-  alien->setUniform("uCameraPosition",
+      model->setUniform("uLight.position", position);
-                    QtkScene::getCamera().getTransform().getTranslation());
+    } else {
-  auto posMatrix = alien->getTransform().toMatrix();
+      qDebug() << "[QtkScene] Failed to set light position: "
+               << lightName.c_str();
+    }
+  };
+
+  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);
+  }
 
-  position = MeshRenderer::getInstance("spartanTestLight")
+  if (auto spartan = getModel("spartanTest"); spartan) {
-                 ->getTransform()
+    setLightPosition("spartanTestLight", spartan);
-                 .getTranslation();
+
-  auto spartan = Model::getInstance("spartanTest");
+    spartan->setUniform("uCameraPosition", cameraPosition);
-  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);
+  }
+
+  if (auto phong = getModel("testPhong"); phong) {
+    setLightPosition("testLight", phong);
 
-  auto phong = MeshRenderer::getInstance("testPhong");
     phong->getTransform().rotate(0.75f, 1.0f, 0.5f, 0.0f);
     phong->bindShaders();
-  position =
+    phong->setUniform("uCameraPosition", cameraPosition);
-      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();
+  }
+
+  // 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(
+  getMesh("noLight")->getTransform().rotate(0.75f, 0.5f, 0.3f, 0.2f);
-      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")
+  getMesh("rgbNormalsCube")->getTransform().rotate(0.75f, 0.2f, 0.4f, 0.6f);
-      ->getTransform()
-      .rotate(0.75f, 0.2f, 0.4f, 0.6f);
 
   // Pitch forward and roll sideways
-  MeshRenderer::getInstance("leftTriangle")
+  getMesh("leftTriangle")->getTransform().rotate(0.75f, 1.0f, 0.0f, 0.0f);
-      ->getTransform()
+  getMesh("rightTriangle")->getTransform().rotate(0.75f, 0.0f, 0.0f, 1.0f);
-      .rotate(0.75f, 1.0f, 0.0f, 0.0f);
-  MeshRenderer::getInstance("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")
+  float posX = getMesh("topTriangle")->getTransform().getTranslation().x();
-                   ->getTransform()
-                   .getTranslation()
-                   .x();
   if (posX < limit || posX > limit + 4.0f) {
     translateX = -translateX;
   }
-  MeshRenderer::getInstance("topTriangle")
+  getMesh("topTriangle")->getTransform().translate(translateX, 0.0f, 0.0f);
-      ->getTransform()
+  getMesh("bottomTriangle")->getTransform().translate(-translateX, 0.0f, 0.0f);
-      .translate(translateX, 0.0f, 0.0f);
-  MeshRenderer::getInstance("bottomTriangle")
-      ->getTransform()
-      .translate(-translateX, 0.0f, 0.0f);
   // And lets rotate the triangles in two directions at once
-  MeshRenderer::getInstance("topTriangle")
+  getMesh("topTriangle")->getTransform().rotate(0.75f, 0.2f, 0.0f, 0.4f);
-      ->getTransform()
+  getMesh("bottomTriangle")->getTransform().rotate(0.75f, 0.0f, 0.2f, 0.4f);
-      .rotate(0.75f, 0.2f, 0.0f, 0.4f);
-  MeshRenderer::getInstance("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")
+  getMesh("centerCube")->getTransform().rotate(0.75f, 0.2f, 0.4f, 0.6f);
-      ->getTransform()
-      .rotate(0.75f, 0.2f, 0.4f, 0.6f);
 }