SDL: Added SDL_HINT_VULKAN_DISPLAY

From 3669d1e76a1ae87863320513fb79e88ce28ba34b Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Sat, 3 Aug 2024 10:06:01 -0700
Subject: [PATCH] Added SDL_HINT_VULKAN_DISPLAY

---
 include/SDL3/SDL_hints.h     | 11 +++++++++++
 src/video/SDL_vulkan_utils.c |  2 +-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/include/SDL3/SDL_hints.h b/include/SDL3/SDL_hints.h
index 7e00e1f9fb986..84682c8b8e475 100644
--- a/include/SDL3/SDL_hints.h
+++ b/include/SDL3/SDL_hints.h
@@ -3373,6 +3373,17 @@ extern "C" {
  */
 #define SDL_HINT_VITA_TOUCH_MOUSE_DEVICE    "SDL_VITA_TOUCH_MOUSE_DEVICE"
 
+/**
+ * A variable overriding the display index used in SDL_Vulkan_CreateSurface()
+ *
+ * The display index starts at 0, which is the default.
+ *
+ * This hint should be set before calling SDL_Vulkan_CreateSurface()
+ *
+ * \since This hint is available since SDL 3.0.0.
+ */
+#define SDL_HINT_VULKAN_DISPLAY "SDL_VULKAN_DISPLAY"
+
 /**
  * Specify the Vulkan library to load.
  *
diff --git a/src/video/SDL_vulkan_utils.c b/src/video/SDL_vulkan_utils.c
index bb42b4933b87a..c5223cdb0a10b 100644
--- a/src/video/SDL_vulkan_utils.c
+++ b/src/video/SDL_vulkan_utils.c
@@ -209,7 +209,7 @@ int SDL_Vulkan_Display_CreateSurface(void *vkGetInstanceProcAddr_,
         SDL_SetError(VK_KHR_DISPLAY_EXTENSION_NAME " extension is not enabled in the Vulkan instance.");
         goto error;
     }
-    chosenDisplayId = SDL_getenv("SDL_VULKAN_DISPLAY");
+    chosenDisplayId = SDL_GetHint(SDL_HINT_VULKAN_DISPLAY);
     if (chosenDisplayId) {
         displayId = SDL_atoi(chosenDisplayId);
     }