Improper UI/display scaling on Linux under Wayland.

[USBDongleGoblin]

If your display scale is set to anything other than 100% while using Wayland, the mouse cursor doesn't correctly align with any UI elements. The attached video shows the issue while on a 4k display with a display scale of 175%. This issue applies to the editor as well.

2025-04-09.19-01-45.webm

[PAMinerva]

I had the same issue, which magically went away on its own after a system update. Don’t ask me what the actual bug was — I have no idea. That said, it’s more likely something related to the desktop environment’s user interface or the compositor rather than an actual bug in WickedEngine. In the meantime, you can use a few tricks to work around it:

• If possible, try logging into a desktop environment that uses X11.

• If that’s not an option, at least try forcing SDL to run through XWayland. Just open a terminal in the directory where the editor executable is, and run:

$ export SDL_VIDEODRIVER=x11    
$ ./WickedEngineEditor

• If neither of those options work for you, here’s a temporary fix you can apply:

WickedEngine/wiCanvas.h

@@ -14,13 +14,15 @@ namespace wi
                uint32_t height = 0;
                float dpi = 96;
                float scaling = 1; // custom DPI scaling factor (optional)
+               float fractional_scaling = 1; // custom fractional scaling factor (optional)
 
                // Create a canvas from physical measurements
-               inline void init(uint32_t width, uint32_t height, float dpi = 96)
+               inline void init(uint32_t width, uint32_t height, float dpi = 96, float fractional_scaling = 1)
                {
                        this->width = width;
                        this->height = height;
                        this->dpi = dpi;
+                       this->fractional_scaling = fractional_scaling;
                }
                // Copy canvas from other canvas
                inline void init(const Canvas& other)
@@ -32,7 +34,7 @@ namespace wi
                {
                        platform::WindowProperties windowprops;
                        platform::GetWindowProperties(window, &windowprops);
-                       init((uint32_t)windowprops.width, (uint32_t)windowprops.height, windowprops.dpi);
+                       init((uint32_t)windowprops.width, (uint32_t)windowprops.height, windowprops.dpi, windowprops.fractional_scaling);
                }
 
                // How many pixels there are per inch

WickedEngine/wiPlatform.h

@@ -66,11 +66,13 @@ namespace wi::platform
                int width = 0;
                int height = 0;
                float dpi = 96;
+               float fractional_scaling = 1;
        };
        inline void GetWindowProperties(window_type window, WindowProperties* dest)
        {
 #ifdef PLATFORM_WINDOWS_DESKTOP
                dest->dpi = (float)GetDpiForWindow(window);
 #endif // WINDOWS_DESKTOP
 
 #ifdef PLATFORM_XBOX
@@ -88,7 +90,8 @@ namespace wi::platform
                int window_width, window_height;
                SDL_GetWindowSize(window, &window_width, &window_height);
                SDL_Vulkan_GetDrawableSize(window, &dest->width, &dest->height);
-               dest->dpi = ((float)dest->width / (float)window_width) * 96.f;
+               dest->fractional_scaling = (float)dest->width / (float)window_width;
+               dest->dpi = dest->fractional_scaling * 96.f;
 #endif // PLATFORM_LINUX
        }
 }

WickedEngine/wiInput.cpp

@@ -183,8 +183,8 @@ namespace wi::input
                }
 
                // The application always works with logical mouse coordinates:
-               mouse.position.x = canvas.PhysicalToLogical(mouse.position.x);
-               mouse.position.y = canvas.PhysicalToLogical(mouse.position.y);
+               mouse.position.x = canvas.PhysicalToLogical(mouse.position.x) * canvas.fractional_scaling;
+               mouse.position.y = canvas.PhysicalToLogical(mouse.position.y) * canvas.fractional_scaling;
 
                // Check if low-level XINPUT controller is not registered for playerindex slot and register:
                for (int i = 0; i < wi::input::xinput::GetMaxControllerCount(); ++i)
@@ -708,8 +708,8 @@ namespace wi::input
        void SetPointer(const XMFLOAT4& props)
        {
                // The application's logical mouse coordinates are converted to the system's physical coordinates:
-               const uint32_t posX = canvas.LogicalToPhysical(props.x);
-               const uint32_t posY = canvas.LogicalToPhysical(props.y);
+               const uint32_t posX = canvas.LogicalToPhysical(props.x) / canvas.fractional_scaling;
+               const uint32_t posY = canvas.LogicalToPhysical(props.y) / canvas.fractional_scaling;
 
 #if defined(PLATFORM_WINDOWS_DESKTOP)
                HWND hWnd = window;

After that, just keep an eye out for any updates to the desktop environment and compositor you are using. Whenever you see those packages get updated, try removing the temporary fixes and see if the issue is finally resolved.