From de87ed3edcd1afecc0d0b58e6edd9bdf2f146e76 Mon Sep 17 00:00:00 2001
From: gdk <gab.dark.100@gmail.com>
Date: Wed, 13 Apr 2022 21:04:32 -0300
Subject: [PATCH] Fix backbuffer not being cleared and scissor not being
 re-enabled on OpenGL

---
 Ryujinx.Graphics.OpenGL/Pipeline.cs | 30 ++++++++++++++++++++++++-----
 Ryujinx.Graphics.OpenGL/Window.cs   |  2 ++
 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/Ryujinx.Graphics.OpenGL/Pipeline.cs b/Ryujinx.Graphics.OpenGL/Pipeline.cs
index 40b45f37a..02d4ab5cd 100644
--- a/Ryujinx.Graphics.OpenGL/Pipeline.cs
+++ b/Ryujinx.Graphics.OpenGL/Pipeline.cs
@@ -1116,12 +1116,32 @@ namespace Ryujinx.Graphics.OpenGL
             {
                 int vIndex = index * 4;
 
-                v[vIndex] = regions[index].X;
-                v[vIndex + 1] = regions[index].Y;
-                v[vIndex + 2] = regions[index].Width;
-                v[vIndex + 3] = regions[index].Height;
+                var region = regions[index];
 
-                GL.Enable(IndexedEnableCap.ScissorTest, index);
+                bool enabled = (region.X | region.Y) != 0 || region.Width != 0xffff || region.Height != 0xffff;
+                uint mask = 1u << index;
+
+                if (enabled)
+                {
+                    v[vIndex] = region.X;
+                    v[vIndex + 1] = region.Y;
+                    v[vIndex + 2] = region.Width;
+                    v[vIndex + 3] = region.Height;
+
+                    if ((_scissorEnables & mask) == 0)
+                    {
+                        _scissorEnables |= mask;
+                        GL.Enable(IndexedEnableCap.ScissorTest, index);
+                    }
+                }
+                else
+                {
+                    if ((_scissorEnables & mask) != 0)
+                    {
+                        _scissorEnables &= ~mask;
+                        GL.Disable(IndexedEnableCap.ScissorTest, index);
+                    }
+                }
             }
 
             GL.ScissorArray(0, count, v);
diff --git a/Ryujinx.Graphics.OpenGL/Window.cs b/Ryujinx.Graphics.OpenGL/Window.cs
index cd8efd129..ae74558e9 100644
--- a/Ryujinx.Graphics.OpenGL/Window.cs
+++ b/Ryujinx.Graphics.OpenGL/Window.cs
@@ -106,6 +106,8 @@ namespace Ryujinx.Graphics.OpenGL
             GL.Disable(EnableCap.RasterizerDiscard);
             GL.Disable(IndexedEnableCap.ScissorTest, 0);
 
+            GL.Clear(ClearBufferMask.ColorBufferBit);
+
             int srcX0, srcX1, srcY0, srcY1;
             float scale = view.ScaleFactor;