Fix Graphics Options VSync left arrow.

Fixes #39.

GameMod/GameMod.csproj

@@ -154,6 +154,7 @@
     <Compile Include="ServerPort.cs" />
     <Compile Include="ServerStatLog.cs" />
     <Compile Include="ServerTrackerPost.cs" />
+    <Compile Include="VSync.cs" />
   </ItemGroup>
   <ItemGroup>
     <Content Include="0Harmony.dll" />

GameMod/VSync.cs

@@ -0,0 +1,56 @@
+using Harmony;
+using Overload;
+using System.Collections.Generic;
+using System.Reflection.Emit;
+
+namespace GameMod
+{
+
+    // Stock game shows 60/30hz for what is actually "full/half" sync rates in Unity, simply change labels
+    [HarmonyPatch(typeof(MenuManager), "GetVSyncSetting")]
+    class VSync_MenuManager_GetVSyncSetting
+    {
+        static IEnumerable<CodeInstruction> Transpiler(IEnumerable<CodeInstruction> codes)
+        {
+            foreach (var code in codes)
+            {
+                if (code.opcode == OpCodes.Ldstr && (string)code.operand == "60 HZ")
+                    code.operand = "100% MONITOR RATE";
+
+                if (code.opcode == OpCodes.Ldstr && (string)code.operand == "30 HZ")
+                    code.operand = "50% MONITOR RATE";
+
+                yield return code;
+            }
+        }
+    }
+
+    // Stock game did not actually implement reverse arrow on vsync option
+    [HarmonyPatch(typeof(MenuManager), "GraphicsOptionsUpdate")]
+    class VSync_MenuManager_GraphicsOptionsUpdate
+    {
+        static IEnumerable<CodeInstruction> Transpiler(IEnumerable<CodeInstruction> codes)
+        {
+            int state = 0;
+            foreach (var code in codes)
+            {
+
+                if (state == 0 && code.opcode == OpCodes.Ldsfld && code.operand == AccessTools.Field(typeof(MenuManager), "gfx_vsync"))
+                    state = 1;
+
+                if (state == 1 && code.opcode == OpCodes.Ldc_I4_3)
+                {
+                    // Original: MenuManager.gfx_vsync = (MenuManager.gfx_vsync + 3 - 1) % 3
+                    // New:      MenuManager.gfx_vsync = (MenuManager.gfx_vsync + 3 + 1 - 1 + UIManager.m_select_dir) % 3
+                    yield return new CodeInstruction(OpCodes.Ldc_I4_1);
+                    yield return new CodeInstruction(OpCodes.Add);
+                    yield return new CodeInstruction(OpCodes.Ldsfld, AccessTools.Field(typeof(UIManager), "m_select_dir"));
+                    yield return new CodeInstruction(OpCodes.Add);
+                    state = 2;
+                }
+
+                yield return code;
+            }
+        }
+    }
+}