headless: fix vulkan exclusive fullscreen ignored

Running in headless mode under wayland (e.g. Sway) compositor, it's not
possible to set any resolution other than 1280x720.

This is because Ryujinx was not updating default surface dimension when
creating swapchain.

src/Ryujinx.Graphics.Gpu/Shader/ShaderSpecializationState.cs

@@ -743,7 +743,7 @@ namespace Ryujinx.Graphics.Gpu.Shader
                 constantBufferUsePerStageMask &= ~(1 << index);
             }
 
-            if (checkTextures)
+            if (checkTextures && _allTextures.Length > 0)
             {
                 TexturePool pool = channel.TextureManager.GetTexturePool(poolState.TexturePoolGpuVa, poolState.TexturePoolMaximumId);
 

src/Ryujinx.Graphics.Vulkan/Window.cs

@@ -10,8 +10,8 @@ namespace Ryujinx.Graphics.Vulkan
 {
     class Window : WindowBase, IDisposable
     {
-        private const int SurfaceWidth = 1280;
-        private const int SurfaceHeight = 720;
+        private uint _surfaceWidth = 1280;
+        private uint _surfaceHeight = 720;
 
         private readonly VulkanRenderer _gd;
         private readonly SurfaceKHR _surface;
@@ -295,15 +295,15 @@ namespace Ryujinx.Graphics.Vulkan
             }
         }
 
-        public static Extent2D ChooseSwapExtent(SurfaceCapabilitiesKHR capabilities)
+        public Extent2D ChooseSwapExtent(SurfaceCapabilitiesKHR capabilities)
         {
             if (capabilities.CurrentExtent.Width != uint.MaxValue)
             {
                 return capabilities.CurrentExtent;
             }
 
-            uint width = Math.Max(capabilities.MinImageExtent.Width, Math.Min(capabilities.MaxImageExtent.Width, SurfaceWidth));
-            uint height = Math.Max(capabilities.MinImageExtent.Height, Math.Min(capabilities.MaxImageExtent.Height, SurfaceHeight));
+            uint width = Math.Max(capabilities.MinImageExtent.Width, Math.Min(capabilities.MaxImageExtent.Width, _surfaceWidth));
+            uint height = Math.Max(capabilities.MinImageExtent.Height, Math.Min(capabilities.MaxImageExtent.Height, _surfaceHeight));
 
             return new Extent2D(width, height);
         }
@@ -630,8 +630,13 @@ namespace Ryujinx.Graphics.Vulkan
 
         public override void SetSize(int width, int height)
         {
-            // We don't need to use width and height as we can get the size from the surface.
-            _swapchainIsDirty = true;
+            if (width > 0 && height > 0)
+            {
+                _surfaceWidth = (uint)width;
+                _surfaceHeight = (uint)height;
+
+                _swapchainIsDirty = true;
+            }
         }
 
         public override void ChangeVSyncMode(bool vsyncEnabled)

src/Ryujinx.Headless.SDL2/Vulkan/VulkanWindow.cs

@@ -29,16 +29,30 @@ namespace Ryujinx.Headless.SDL2.Vulkan
 
         protected override void InitializeRenderer()
         {
+            int width = DefaultWidth;
+            int height = DefaultHeight;
+
             if (IsExclusiveFullscreen)
             {
-                Renderer?.Window.SetSize(ExclusiveFullscreenWidth, ExclusiveFullscreenHeight);
-                MouseDriver.SetClientSize(ExclusiveFullscreenWidth, ExclusiveFullscreenHeight);
+                width = ExclusiveFullscreenWidth;
+                height = ExclusiveFullscreenHeight;
             }
-            else
+            else if (IsFullscreen)
             {
-                Renderer?.Window.SetSize(DefaultWidth, DefaultHeight);
-                MouseDriver.SetClientSize(DefaultWidth, DefaultHeight);
+                // NOTE: grabbing the main display's dimensions directly as OpenGL doesn't scale along like the VulkanWindow.
+                if (SDL_GetDisplayBounds(DisplayId, out SDL_Rect displayBounds) < 0)
+                {
+                    Logger.Warning?.Print(LogClass.Application, $"Could not retrieve display bounds: {SDL_GetError()}");
+                }
+                else
+                {
+                    width = displayBounds.w;
+                    height = displayBounds.h;
+                }
             }
+
+            Renderer?.Window.SetSize(width, height);
+            MouseDriver.SetClientSize(width, height);
         }
 
         private static void BasicInvoke(Action action)