From 24cea1972cc2445c71eff851ba0e1e1d563b0d2d Mon Sep 17 00:00:00 2001
From: BearOso <bearoso@gmail.com>
Date: Wed, 15 Mar 2023 15:54:43 -0500
Subject: [PATCH] win32: Don't allow Vulkan and OpenGL to be used in the same
 session.

---
 win32/win32_display.cpp | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/win32/win32_display.cpp b/win32/win32_display.cpp
index 63d030b0..26a22c15 100644
--- a/win32/win32_display.cpp
+++ b/win32/win32_display.cpp
@@ -115,6 +115,8 @@ returns true if successful, false otherwise
 */
 bool WinDisplayReset(void)
 {
+	static bool VulkanUsed = false;
+	static bool OpenGLUsed = false;
 	S9xDisplayOutput->DeInitialize();
 	FlushMessageQueue();
 
@@ -129,10 +131,22 @@ bool WinDisplayReset(void)
 			break;
 #endif
 		case OPENGL:
+			if (VulkanUsed)
+			{
+				MessageBox(GUI.hWnd, TEXT("Changing to OpenGL requires a restart if you've already used Vulkan"), TEXT("Snes9x Display Driver"), MB_OK);
+				break;
+			}
 			S9xDisplayOutput = &OpenGL;
+			OpenGLUsed = true;
 			break;
 		case VULKAN:
+			if (OpenGLUsed)
+			{
+				MessageBox(GUI.hWnd, TEXT("Changing to Vulkan requires a restart if you've already used OpenGL"), TEXT("Snes9x Display Driver"), MB_OK);
+				break;
+			}
 			S9xDisplayOutput = &VulkanDriver;
+			VulkanUsed = true;
 			break;
 	}