SDL: Add support for GPU RGB565 (B5G6R5_UNORM) textures with DX11 (#14358)

SDL Commits
1 
From a76fb7b2fb707b6abf4f7c281b0ba4ae0d5aeb64 Mon Sep 17 00:00:00 2001
From: Kirill Andriiashin <[EMAIL REDACTED]>
Date: Wed, 29 Oct 2025 20:39:58 +0300
Subject: [PATCH] Add support for GPU RGB565 (B5G6R5_UNORM) textures with DX11
 (#14358)

---
 src/render/direct3d11/SDL_render_d3d11.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/render/direct3d11/SDL_render_d3d11.c b/src/render/direct3d11/SDL_render_d3d11.c
index dd46fcf0b33d0..1cfafe545334c 100644
--- a/src/render/direct3d11/SDL_render_d3d11.c
+++ b/src/render/direct3d11/SDL_render_d3d11.c
@@ -292,6 +292,8 @@ static DXGI_FORMAT SDLPixelFormatToDXGITextureFormat(Uint32 format, Uint32 outpu
         return DXGI_FORMAT_NV12;
     case SDL_PIXELFORMAT_P010:
         return DXGI_FORMAT_P010;
+    case SDL_PIXELFORMAT_RGB565:
+        return DXGI_FORMAT_B5G6R5_UNORM;
     default:
         return DXGI_FORMAT_UNKNOWN;
     }
@@ -2915,6 +2917,11 @@ static bool D3D11_CreateRenderer(SDL_Renderer *renderer, SDL_Window *window, SDL
         return false;
     }
 
+    // DXGI_FORMAT_B5G6R5_UNORM is supported since Direct3D 11.1 on Windows 8 and later
+    if (data->featureLevel >= D3D_FEATURE_LEVEL_11_1 && WIN_IsWindows8OrGreater()) {
+        SDL_AddSupportedTextureFormat(renderer, SDL_PIXELFORMAT_RGB565);
+    }
+
     return true;
 }