[GPU] Avoid drawing the frame buffer with alpha blend enabled, use correct blend enable register, clear the buffer before drawing

Ryujinx.Graphics/Gal/OpenGL/OGLFrameBuffer.cs

@@ -184,6 +184,10 @@ namespace Ryujinx.Graphics.Gal.OpenGL
             {
                 EnsureInitialized();
 
+                bool AlphaBlendEnable = GL.GetInteger(GetPName.Blend) != 0;
+
+                GL.Disable(EnableCap.Blend);
+
                 GL.ActiveTexture(TextureUnit.Texture0);
 
                 GL.BindTexture(TextureTarget.Texture2D, CurrTexHandle);
@@ -192,6 +196,10 @@ namespace Ryujinx.Graphics.Gal.OpenGL
 
                 GL.BindFramebuffer(FramebufferTarget.Framebuffer, 0);
 
+                GL.Clear(
+                    ClearBufferMask.ColorBufferBit |
+                    ClearBufferMask.DepthBufferBit);
+
                 GL.BindVertexArray(VaoHandle);
 
                 GL.UseProgram(Shader.Handle);
@@ -202,6 +210,11 @@ namespace Ryujinx.Graphics.Gal.OpenGL
                 GL.BindFramebuffer(FramebufferTarget.Framebuffer, CurrFbHandle);
 
                 GL.UseProgram(CurrentProgram);
+
+                if (AlphaBlendEnable)
+                {
+                    GL.Enable(EnableCap.Blend);
+                }
             }
         }
 
@@ -289,9 +302,11 @@ namespace Ryujinx.Graphics.Gal.OpenGL
         {
             GL.BindTexture(TextureTarget.Texture2D, Handle);
 
-            GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (int)TextureMinFilter.Linear);
+            const int MinFilter = (int)TextureMinFilter.Linear;
+            const int MagFilter = (int)TextureMagFilter.Linear;
 
-            GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (int)TextureMagFilter.Linear);
+            GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, MinFilter);
+            GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, MagFilter);
 
             (PixelFormat Format, PixelType Type) = OGLEnumConverter.GetTextureFormat(GalTextureFormat.A8B8G8R8);
 

Ryujinx.Graphics/Gpu/NvGpuEngine3d.cs

@@ -168,7 +168,7 @@ namespace Ryujinx.Graphics.Gpu
         private void SetAlphaBlending()
         {
             //TODO: Support independent blend properly.
-            bool Enable = (ReadRegister(NvGpuEngine3dReg.IBlendEnable) & 1) != 0;
+            bool Enable = (ReadRegister(NvGpuEngine3dReg.IBlendNEnable) & 1) != 0;
 
             Gpu.Renderer.SetBlendEnable(Enable);
 

Ryujinx.Graphics/Gpu/NvGpuEngine3dReg.cs

@@ -16,6 +16,7 @@ namespace Ryujinx.Graphics.Gpu
         BlendFuncSrcAlpha    = 0x4d4,
         BlendFuncDstAlpha    = 0x4d6,
         BlendEnableMaster    = 0x4d7,
+        IBlendNEnable        = 0x4d8,
         VertexArrayElemBase  = 0x50d,
         TexHeaderPoolOffset  = 0x55d,
         TexSamplerPoolOffset = 0x557,