From 63a019b7493d83c62a55a106ca97bbe38f6b7676 Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Wed, 21 Dec 2022 22:13:23 -0800
Subject: [PATCH] Qt: Start OpenGL bug list with glFlush cross-thread on
 Windows (fixes #2761)

---
 src/platform/qt/CMakeLists.txt |  1 +
 src/platform/qt/DisplayGL.cpp  |  9 ++++++++-
 src/platform/qt/OpenGLBug.cpp  | 34 ++++++++++++++++++++++++++++++++++
 src/platform/qt/OpenGLBug.h    | 17 +++++++++++++++++
 4 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 src/platform/qt/OpenGLBug.cpp
 create mode 100644 src/platform/qt/OpenGLBug.h

diff --git a/src/platform/qt/CMakeLists.txt b/src/platform/qt/CMakeLists.txt
index 9b1f60288..204f8e89a 100644
--- a/src/platform/qt/CMakeLists.txt
+++ b/src/platform/qt/CMakeLists.txt
@@ -118,6 +118,7 @@ set(SOURCE_FILES
 	MessagePainter.cpp
 	MultiplayerController.cpp
 	ObjView.cpp
+	OpenGLBug.cpp
 	OverrideView.cpp
 	PaletteView.cpp
 	PlacementControl.cpp
diff --git a/src/platform/qt/DisplayGL.cpp b/src/platform/qt/DisplayGL.cpp
index 4b0fcdce3..0528922fb 100644
--- a/src/platform/qt/DisplayGL.cpp
+++ b/src/platform/qt/DisplayGL.cpp
@@ -44,6 +44,8 @@ using QOpenGLFunctions_Baseline = QOpenGLFunctions_3_2_Core;
 #define OVERHEAD_NSEC 300000
 #endif
 
+#include "OpenGLBug.h"
+
 using namespace QGBA;
 
 QHash<QSurfaceFormat, bool> DisplayGL::s_supports;
@@ -959,7 +961,12 @@ QOpenGLContext* PainterGL::shareContext() {
 
 void PainterGL::updateFramebufferHandle() {
 	QOpenGLFunctions_Baseline* fn = m_gl->versionFunctions<QOpenGLFunctions_Baseline>();
-	fn->glFlush();
+	// TODO: Figure out why glFlush doesn't work here on Intel/Windows
+	if (glContextHasBug(OpenGLBug::CROSS_THREAD_FLUSH)) {
+		fn->glFinish();
+	} else {
+		fn->glFlush();
+	}
 
 	CoreController::Interrupter interrupter(m_context);
 	if (!m_context->hardwareAccelerated()) {
diff --git a/src/platform/qt/OpenGLBug.cpp b/src/platform/qt/OpenGLBug.cpp
new file mode 100644
index 000000000..e00310c56
--- /dev/null
+++ b/src/platform/qt/OpenGLBug.cpp
@@ -0,0 +1,34 @@
+/* Copyright (c) 2013-2022 Jeffrey Pfau
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include "OpenGLBug.h"
+
+#include <QOpenGLContext>
+#include <QOpenGLFunctions>
+
+namespace QGBA {
+
+bool glContextHasBug(OpenGLBug bug) {
+	QOpenGLContext* context = QOpenGLContext::currentContext();
+	if (!context) {
+		abort();
+	}
+	QOpenGLFunctions* fn = context->functions();
+	QString vendor(reinterpret_cast<const char*>(fn->glGetString(GL_VENDOR)));
+	QString renderer(reinterpret_cast<const char*>(fn->glGetString(GL_RENDERER)));
+
+	switch (bug) {
+	case OpenGLBug::CROSS_THREAD_FLUSH:
+#ifndef Q_OS_WIN
+		return false;
+#else
+		return vendor == "Intel";
+#endif
+	default:
+		return false;
+	}
+}
+
+}
diff --git a/src/platform/qt/OpenGLBug.h b/src/platform/qt/OpenGLBug.h
new file mode 100644
index 000000000..fda0ed555
--- /dev/null
+++ b/src/platform/qt/OpenGLBug.h
@@ -0,0 +1,17 @@
+/* Copyright (c) 2013-2022 Jeffrey Pfau
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#pragma once
+
+namespace QGBA {
+
+enum class OpenGLBug {
+    // mgba.io/i/2761
+    CROSS_THREAD_FLUSH
+};
+
+bool glContextHasBug(OpenGLBug);
+
+}