From 3eea50654fce43a27e1006cb8984a2f10f9cfc26 Mon Sep 17 00:00:00 2001
From: Brandon Wright <bearoso@gmail.com>
Date: Fri, 28 Dec 2018 12:06:00 -0600
Subject: [PATCH] GTK+: OpenGL: Separate glFinish and glFenceSync options.

---
 gtk/src/gtk_config.cpp                |  7 +++++--
 gtk/src/gtk_config.h                  |  1 +
 gtk/src/gtk_display_driver_opengl.cpp | 22 ++++++++++------------
 gtk/src/gtk_preferences.cpp           |  2 ++
 gtk/src/snes9x.ui                     | 25 ++++++++++++++++++++-----
 5 files changed, 38 insertions(+), 19 deletions(-)

diff --git a/gtk/src/gtk_config.cpp b/gtk/src/gtk_config.cpp
index b08bc6be..dfec951c 100644
--- a/gtk/src/gtk_config.cpp
+++ b/gtk/src/gtk_config.cpp
@@ -149,6 +149,7 @@ int Snes9xConfig::load_defaults ()
     use_shaders = 0;
     shader_filename[0] = '\0';
     sync_every_frame = FALSE;
+    use_fences = FALSE;
 #endif
 
     /* Snes9X Variables */
@@ -263,7 +264,8 @@ int Snes9xConfig::save_config_file ()
 #undef z
 #define z "OpenGL::"
     outbool   (cf, z"VSync", sync_to_vblank);
-    outbool   (cf, z"ReduceInputLag", sync_every_frame);
+    outbool   (cf, z"glFinish", sync_every_frame);
+    outbool   (cf, z"glFenceSync", use_fences);
     outbool   (cf, z"UsePixelBufferObjects", use_pbos);
     cf.SetInt     (z"PixelBufferObjectBitDepth", pbo_format);
     outbool   (cf, z"UseNonPowerOfTwoTextures", npot_textures);
@@ -493,7 +495,8 @@ int Snes9xConfig::load_config_file ()
 #undef z
 #define z "OpenGL::"
     inbool (z"VSync", sync_to_vblank);
-    inbool (z"ReduceInputLag", sync_every_frame);
+    inbool (z"glFinish", sync_every_frame);
+    inbool (z"glFenceSync", use_fences);
     inbool (z"UsePixelBufferObjects", use_pbos);
     inint  (z"PixelBufferObjectBitDepth", pbo_format);
     inbool (z"UseNonPowerOfTwoTextures", npot_textures);
diff --git a/gtk/src/gtk_config.h b/gtk/src/gtk_config.h
index 7aad3c31..c173b8d5 100644
--- a/gtk/src/gtk_config.h
+++ b/gtk/src/gtk_config.h
@@ -150,6 +150,7 @@ class Snes9xConfig
     unsigned char use_shaders;
     char          shader_filename[PATH_MAX];
     unsigned char sync_every_frame;
+    unsigned char use_fences;
 #endif
 
     JoyDevice **joystick;
diff --git a/gtk/src/gtk_display_driver_opengl.cpp b/gtk/src/gtk_display_driver_opengl.cpp
index 63cd8d93..16d1d361 100644
--- a/gtk/src/gtk_display_driver_opengl.cpp
+++ b/gtk/src/gtk_display_driver_opengl.cpp
@@ -646,19 +646,16 @@ void S9xOpenGLDisplayDriver::swap_buffers ()
 {
     context->swap_buffers ();
 
-    if (config->sync_every_frame)
+    if (config->sync_every_frame && !config->use_fences)
     {
-        if (fences)
-        {
-            if (fence)
-                glDeleteSync (fence);
-            fence = glFenceSync (GL_SYNC_GPU_COMMANDS_COMPLETE, 0);
-        }
-        else
-        {
-            usleep (0);
-            glFinish ();
-        }
+        usleep (0);
+        glFinish ();
+    }
+    else if (config->use_fences && fences)
+    {
+        if (fence)
+            glDeleteSync (fence);
+        fence = glFenceSync (GL_SYNC_GPU_COMMANDS_COMPLETE, 0);
     }
 }
 
@@ -731,5 +728,6 @@ bool S9xOpenGLDisplayDriver::is_ready ()
 
     glDeleteSync (fence);
     fence = NULL;
+
     return true;
 }
diff --git a/gtk/src/gtk_preferences.cpp b/gtk/src/gtk_preferences.cpp
index 9df837b5..74968732 100644
--- a/gtk/src/gtk_preferences.cpp
+++ b/gtk/src/gtk_preferences.cpp
@@ -708,6 +708,7 @@ Snes9xPreferences::move_settings_to_dialog ()
 #ifdef USE_OPENGL
     set_check ("sync_to_vblank",            config->sync_to_vblank);
     set_check ("sync_every_frame",          config->sync_every_frame);
+    set_check ("use_fences",                config->use_fences);
     set_check ("use_pbos",                  config->use_pbos);
     set_combo ("pixel_format",              config->pbo_format == 16 ? 0 : 1);
     set_check ("npot_textures",             config->npot_textures);
@@ -865,6 +866,7 @@ Snes9xPreferences::get_settings_from_dialog ()
     config->npot_textures             = get_check ("npot_textures");
     config->use_shaders               = get_check ("use_shaders");
     config->sync_every_frame          = get_check ("sync_every_frame");
+    config->use_fences                = get_check ("use_fences");
 
     sstrncpy (config->shader_filename, get_entry_text ("fragment_shader"), PATH_MAX);
 
diff --git a/gtk/src/snes9x.ui b/gtk/src/snes9x.ui
index bab3eee1..402c1676 100644
--- a/gtk/src/snes9x.ui
+++ b/gtk/src/snes9x.ui
@@ -3819,7 +3819,7 @@
                                             </child>
                                             <child>
                                               <object class="GtkCheckButton" id="sync_every_frame">
-                                                <property name="label" translatable="yes">Reduce input lag</property>
+                                                <property name="label" translatable="yes">Reduce input lag with glFinish</property>
                                                 <property name="visible">True</property>
                                                 <property name="can_focus">True</property>
                                                 <property name="receives_default">False</property>
@@ -3832,6 +3832,21 @@
                                                 <property name="position">1</property>
                                               </packing>
                                             </child>
+                                            <child>
+                                              <object class="GtkCheckButton" id="use_fences">
+                                                <property name="label" translatable="yes">Reduce input lag with glFenceSync</property>
+                                                <property name="visible">True</property>
+                                                <property name="can_focus">True</property>
+                                                <property name="receives_default">False</property>
+                                                <property name="tooltip_text" translatable="yes">Sync the program with the video output after every displayed frame to reduce input latency, but allow GUI events to occur in the meantime</property>
+                                                <property name="draw_indicator">True</property>
+                                              </object>
+                                              <packing>
+                                                <property name="expand">False</property>
+                                                <property name="fill">True</property>
+                                                <property name="position">2</property>
+                                              </packing>
+                                            </child>
                                             <child>
                                               <object class="GtkCheckButton" id="npot_textures">
                                                 <property name="label" translatable="yes">Allow non-power-of-two textures</property>
@@ -3844,7 +3859,7 @@
                                               <packing>
                                                 <property name="expand">False</property>
                                                 <property name="fill">True</property>
-                                                <property name="position">2</property>
+                                                <property name="position">3</property>
                                               </packing>
                                             </child>
                                             <child>
@@ -3860,7 +3875,7 @@
                                               <packing>
                                                 <property name="expand">False</property>
                                                 <property name="fill">True</property>
-                                                <property name="position">3</property>
+                                                <property name="position">4</property>
                                               </packing>
                                             </child>
                                             <child>
@@ -3914,7 +3929,7 @@
                                               <packing>
                                                 <property name="expand">False</property>
                                                 <property name="fill">True</property>
-                                                <property name="position">4</property>
+                                                <property name="position">5</property>
                                               </packing>
                                             </child>
                                             <child>
@@ -3972,7 +3987,7 @@
                                               <packing>
                                                 <property name="expand">False</property>
                                                 <property name="fill">True</property>
-                                                <property name="position">5</property>
+                                                <property name="position">6</property>
                                               </packing>
                                             </child>
                                           </object>