Add graphics backend selection

app/config/config.cpp

@@ -144,6 +144,8 @@ void Config::SetDefaults()
 	SetEntryInternal(QStringLiteral("PreviewNonFloatDontAskAgain"),
 					 NodeValue::kBoolean, false);
 	SetEntryInternal(QStringLiteral("UseGLFinish"), NodeValue::kBoolean, false);
+	SetEntryInternal(QStringLiteral("GraphicsBackend"), NodeValue::kText,
+					 QStringLiteral("opengl"));
 	SetEntryInternal(QStringLiteral("RenderProcessIsolationEnabled"),
 					 NodeValue::kBoolean, false);
 

app/dialog/preferences/tabs/preferencesbehaviortab.cpp

@@ -22,6 +22,7 @@
 #include "preferencesbehaviortab.h"
 
 #include <QCheckBox>
+#include <QComboBox>
 #include <QVBoxLayout>
 
 #include "config/config.h"
@@ -36,7 +37,8 @@ PreferencesBehaviorTab::PreferencesBehaviorTab()
 	behavior_tree_ = new QTreeWidget();
 	layout->addWidget(behavior_tree_);
 
-	behavior_tree_->setHeaderLabel(tr("Behavior"));
+	behavior_tree_->setColumnCount(2);
+	behavior_tree_->setHeaderLabels({ tr("Behavior"), tr("Setting") });
 
 	QTreeWidgetItem *general_group = AddParent(tr("General"));
 	AddItem(
@@ -97,7 +99,30 @@ PreferencesBehaviorTab::PreferencesBehaviorTab()
 		   "dependencies among clips when copying or splitting them."),
 		node_group);
 
-	QTreeWidgetItem *opengl_group = AddParent(tr("OpenGL"));
+	QTreeWidgetItem *rendering_group = AddParent(tr("Rendering"));
+	QTreeWidgetItem *graphics_backend_item =
+		new QTreeWidgetItem({ tr("Graphics Backend") });
+	graphics_backend_item->setToolTip(
+		0, tr("Selects the graphics API Oak should request on next launch. "
+			  "Vulkan is experimental and currently falls back to the OpenGL "
+			  "renderer for timeline/viewer rendering."));
+	rendering_group->addChild(graphics_backend_item);
+	graphics_backend_combobox_ = new QComboBox();
+	graphics_backend_combobox_->addItem(tr("OpenGL"), QStringLiteral("opengl"));
+	graphics_backend_combobox_->addItem(tr("Vulkan (experimental)"),
+										QStringLiteral("vulkan"));
+	const QString current_backend =
+		OLIVE_CONFIG("GraphicsBackend").toString().toLower();
+	const int backend_index = graphics_backend_combobox_->findData(
+		current_backend.isEmpty() ? QStringLiteral("opengl")
+								  : current_backend);
+	graphics_backend_combobox_->setCurrentIndex(backend_index >= 0
+													? backend_index
+													: 0);
+	behavior_tree_->setItemWidget(graphics_backend_item, 1,
+								  graphics_backend_combobox_);
+
+	QTreeWidgetItem *opengl_group = AddParent(tr("OpenGL"), rendering_group);
 	AddItem(tr("Use glFinish"), QStringLiteral("UseGLFinish"), opengl_group);
 }
 
@@ -110,6 +135,9 @@ void PreferencesBehaviorTab::Accept(MultiUndoCommand *command)
 		OLIVE_CONFIG_STR(iterator.value()) =
 			(iterator.key()->checkState(0) == Qt::Checked);
 	}
+
+	OLIVE_CONFIG("GraphicsBackend") =
+		graphics_backend_combobox_->currentData().toString();
 }
 
 QTreeWidgetItem *PreferencesBehaviorTab::AddItem(const QString &text,

app/dialog/preferences/tabs/preferencesbehaviortab.h

@@ -22,6 +22,7 @@
 #ifndef PREFERENCESBEHAVIORTAB_H
 #define PREFERENCESBEHAVIORTAB_H
 
+#include <QComboBox>
 #include <QTreeWidget>
 
 #include "dialog/configbase/configdialogbase.h"
@@ -49,6 +50,8 @@ private:
 
 	QMap<QTreeWidgetItem *, QString> config_map_;
 
+	QComboBox *graphics_backend_combobox_;
+
 	QTreeWidget *behavior_tree_;
 };
 

app/main.cpp

@@ -41,6 +41,7 @@ extern "C" {
 #include <QIcon>
 #include <QSurfaceFormat>
 
+#include "config/config.h"
 #include "core.h"
 #include "common/commandlineparser.h"
 #include "common/debug.h"
@@ -300,7 +301,8 @@ int main(int argc, char *argv[])
 
 	startup_params.set_startup_project(project_argument->GetSetting());
 
-	// Set OpenGL display profile
+	// Set OpenGL display profile. Oak's render pipeline still uses OpenGL
+	// internally even when Vulkan is requested as the Qt graphics backend.
 	QSurfaceFormat format;
 
 	// Tries to cover all bases. If drivers don't support 3.2, they should fallback to the closest
@@ -338,6 +340,16 @@ int main(int argc, char *argv[])
 		a.reset(new QCoreApplication(argc, argv));
 	}
 
+	olive::Config::Load();
+	const QString graphics_backend =
+		olive::Config::Current()[QStringLiteral("GraphicsBackend")]
+			.toString()
+			.toLower();
+	qputenv("QSG_RHI_BACKEND",
+			graphics_backend == QStringLiteral("vulkan")
+				? QByteArrayLiteral("vulkan")
+				: QByteArrayLiteral("opengl"));
+
 	if (auto *gui_app = qobject_cast<QGuiApplication *>(a.get())) {
 		gui_app->setWindowIcon(QIcon(QStringLiteral(":/graphics/oak-logo.png")));
 	}

app/render/rendermanager.cpp

@@ -40,11 +40,53 @@ namespace olive
 RenderManager *RenderManager::instance_ = nullptr;
 const rational RenderManager::kDryRunInterval = rational(10);
 
+RenderManager::Backend RenderManager::BackendFromString(const QString &backend)
+{
+	const QString lower = backend.toLower();
+	if (lower == QStringLiteral("vulkan")) {
+		return kVulkan;
+	}
+
+	if (lower == QStringLiteral("multiprocess")) {
+		return kMultiProcess;
+	}
+
+	if (lower == QStringLiteral("dummy")) {
+		return kDummy;
+	}
+
+	return kOpenGL;
+}
+
+QString RenderManager::BackendToString(Backend backend)
+{
+	switch (backend) {
+	case kOpenGL:
+		return QStringLiteral("opengl");
+	case kVulkan:
+		return QStringLiteral("vulkan");
+	case kMultiProcess:
+		return QStringLiteral("multiprocess");
+	case kDummy:
+		return QStringLiteral("dummy");
+	}
+
+	return QStringLiteral("opengl");
+}
+
 RenderManager::RenderManager(QObject *parent)
 	: backend_(kOpenGL)
+	, requested_backend_(BackendFromString(
+		  OLIVE_CONFIG("GraphicsBackend").toString()))
 	, aggressive_gc_(0)
 	, worker_pool_(nullptr)
 {
+	if (requested_backend_ == kVulkan) {
+		qWarning()
+			<< "Vulkan graphics backend was requested, but the current render "
+			   "pipeline still uses OpenGL. Falling back to OpenGL renderer.";
+	}
+
 	if (backend_ == kOpenGL) {
 		context_ = new OpenGLRenderer();
 		decoder_cache_ = new DecoderCache();

app/render/rendermanager.h

@@ -78,6 +78,9 @@ public:
 		/// Graphics acceleration provided by OpenGL
 		kOpenGL,
 
+		/// Vulkan requested by the user. Falls back to OpenGL until VulkanRenderer is implemented.
+		kVulkan,
+
 		/// Video frames are rendered by an external olive-render-worker process.
 		kMultiProcess,
 
@@ -201,6 +204,14 @@ public:
 		return backend_;
 	}
 
+	Backend requested_backend() const
+	{
+		return requested_backend_;
+	}
+
+	static Backend BackendFromString(const QString &backend);
+	static QString BackendToString(Backend backend);
+
 	PreviewAutoCacher *GetCacher() const
 	{
 		return auto_cacher_;
@@ -228,6 +239,7 @@ private:
 	Renderer *context_;
 
 	Backend backend_;
+	Backend requested_backend_;
 
 	DecoderCache *decoder_cache_;