From fd7d698ee0c7c50f8c540e3d06fb8662f6381600 Mon Sep 17 00:00:00 2001
From: wwylele <wwylele@gmail.com>
Date: Sun, 4 Sep 2016 19:41:44 +0800
Subject: [PATCH] Hack VSync: use sleep

---
 src/citra_qt/bootmanager.cpp |  2 +-
 src/core/hw/gpu.cpp          | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/citra_qt/bootmanager.cpp b/src/citra_qt/bootmanager.cpp
index d6c928fc7..c7e19429a 100644
--- a/src/citra_qt/bootmanager.cpp
+++ b/src/citra_qt/bootmanager.cpp
@@ -276,7 +276,7 @@ void GRenderWindow::InitRenderTarget() {
     QGLFormat fmt;
     fmt.setVersion(3, 3);
     fmt.setProfile(QGLFormat::CoreProfile);
-    fmt.setSwapInterval(Settings::values.use_vsync);
+    fmt.setSwapInterval(false);
 
     // Requests a forward-compatible context, which is required to get a 3.2+ context on OS X
     fmt.setOption(QGL::NoDeprecatedFunctions);
diff --git a/src/core/hw/gpu.cpp b/src/core/hw/gpu.cpp
index a4dfb7e43..671c353ff 100644
--- a/src/core/hw/gpu.cpp
+++ b/src/core/hw/gpu.cpp
@@ -2,8 +2,10 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <chrono>
 #include <cstring>
 #include <numeric>
+#include <thread>
 #include <type_traits>
 
 #include "common/color.h"
@@ -411,6 +413,19 @@ static void VBlankCallback(u64 userdata, int cycles_late) {
     last_skip_frame = g_skip_frame;
     g_skip_frame = (frame_count & Settings::values.frame_skip) != 0;
 
+    if (Settings::values.use_vsync) {
+        using namespace std::chrono;
+        static auto frame_time = high_resolution_clock::now();
+        static constexpr auto update_duration = duration_cast<high_resolution_clock::duration>(16667us);
+        auto now = high_resolution_clock::now();
+        if (now < frame_time) {
+            std::this_thread::sleep_until(frame_time);
+            frame_time += update_duration;
+        } else {
+            frame_time = now + update_duration;
+        }
+    }
+
     // Swap buffers based on the frameskip mode, which is a little bit tricky. When
     // a frame is being skipped, nothing is being rendered to the internal framebuffer(s).
     // So, we should only swap frames if the last frame was rendered. The rules are: