From 7b5eedea3261abdc8925fb3a3806d5f4627a7122 Mon Sep 17 00:00:00 2001
From: "alexey.lysiuk" <alexey.lysiuk@gmail.com>
Date: Tue, 12 Mar 2019 15:47:27 +0200
Subject: [PATCH] - implemented OpenGL / Vulkan switch in SDL backend

---
 src/posix/sdl/sdlglvideo.cpp | 26 +++++++++++++-------------
 src/v_video.cpp              |  9 +++++++++
 src/win32/hardware.cpp       | 10 +---------
 3 files changed, 23 insertions(+), 22 deletions(-)

diff --git a/src/posix/sdl/sdlglvideo.cpp b/src/posix/sdl/sdlglvideo.cpp
index 2b261de43..188b3c265 100644
--- a/src/posix/sdl/sdlglvideo.cpp
+++ b/src/posix/sdl/sdlglvideo.cpp
@@ -72,6 +72,7 @@ EXTERN_CVAR (Int, vid_displaybits)
 EXTERN_CVAR (Int, vid_maxfps)
 EXTERN_CVAR (Int, vid_defwidth)
 EXTERN_CVAR (Int, vid_defheight)
+EXTERN_CVAR (Int, vid_backend)
 EXTERN_CVAR (Bool, cl_capfps)
 
 // PUBLIC DATA DEFINITIONS -------------------------------------------------
@@ -111,7 +112,7 @@ namespace Priv
 	static const int MIN_HEIGHT = 200;
 
 	SDL_Window *window;
-	bool vulkanSupported;
+	bool vulkanEnabled;
 	bool fullscreenSwitch;
 
 	void CreateWindow(uint32_t extraFlags)
@@ -197,7 +198,7 @@ private:
 
 void I_GetVulkanDrawableSize(int *width, int *height)
 {
-	assert(Priv::vulkanSupported);
+	assert(Priv::vulkanEnabled);
 	assert(Priv::window != nullptr);
 	assert(Priv::Vulkan_GetDrawableSize);
 	Priv::Vulkan_GetDrawableSize(Priv::window, width, height);
@@ -205,17 +206,15 @@ void I_GetVulkanDrawableSize(int *width, int *height)
 
 bool I_GetVulkanPlatformExtensions(unsigned int *count, const char **names)
 {
-	assert(Priv::vulkanSupported);
+	assert(Priv::vulkanEnabled);
 	assert(Priv::window != nullptr);
-	assert(Priv::Vulkan_GetInstanceExtensions);
 	return Priv::Vulkan_GetInstanceExtensions(Priv::window, count, names) == SDL_TRUE;
 }
 
 bool I_CreateVulkanSurface(VkInstance instance, VkSurfaceKHR *surface)
 {
-	assert(Priv::vulkanSupported);
+	assert(Priv::vulkanEnabled);
 	assert(Priv::window != nullptr);
-	assert(Priv::Vulkan_CreateSurface);
 	return Priv::Vulkan_CreateSurface(Priv::window, instance, surface) == SDL_TRUE;
 }
 
@@ -234,15 +233,16 @@ SDLVideo::SDLVideo ()
 		Priv::library.Load({ "libSDL2.so", "libSDL2-2.0.so" });
 	}
 
-	Priv::vulkanSupported = Priv::Vulkan_GetDrawableSize && Priv::Vulkan_GetInstanceExtensions && Priv::Vulkan_CreateSurface;
+	Priv::vulkanEnabled = vid_backend == 0
+		&& Priv::Vulkan_GetDrawableSize && Priv::Vulkan_GetInstanceExtensions && Priv::Vulkan_CreateSurface;
 
-	if (Priv::vulkanSupported)
+	if (Priv::vulkanEnabled)
 	{
 		Priv::CreateWindow(Priv::VulkanWindowFlag | SDL_WINDOW_HIDDEN);
 
 		if (Priv::window == nullptr)
 		{
-			Priv::vulkanSupported = false;
+			Priv::vulkanEnabled = false;
 		}
 	}
 }
@@ -257,7 +257,7 @@ DFrameBuffer *SDLVideo::CreateFrameBuffer ()
 	SystemBaseFrameBuffer *fb = nullptr;
 
 	// first try Vulkan, if that fails OpenGL
-	if (Priv::vulkanSupported)
+	if (Priv::vulkanEnabled)
 	{
 		try
 		{
@@ -267,7 +267,7 @@ DFrameBuffer *SDLVideo::CreateFrameBuffer ()
 		}
 		catch (CRecoverableError const&)
 		{
-			Priv::vulkanSupported = false;
+			Priv::vulkanEnabled = false;
 		}
 	}
 
@@ -302,7 +302,7 @@ int SystemBaseFrameBuffer::GetClientWidth()
 {
 	int width = 0;
 
-	assert(Priv::vulkanSupported);
+	assert(Priv::vulkanEnabled);
 	Priv::Vulkan_GetDrawableSize(Priv::window, &width, nullptr);
 
 	return width;
@@ -312,7 +312,7 @@ int SystemBaseFrameBuffer::GetClientHeight()
 {
 	int height = 0;
 
-	assert(Priv::vulkanSupported);
+	assert(Priv::vulkanEnabled);
 	Priv::Vulkan_GetDrawableSize(Priv::window, nullptr, &height);
 
 	return height;
diff --git a/src/v_video.cpp b/src/v_video.cpp
index 61a9ceb7b..d0085a153 100644
--- a/src/v_video.cpp
+++ b/src/v_video.cpp
@@ -113,6 +113,15 @@ CUSTOM_CVAR(Int, vid_rendermode, 4, CVAR_ARCHIVE | CVAR_GLOBALCONFIG | CVAR_NOIN
 	// No further checks needed. All this changes now is which scene drawer the render backend calls.
 }
 
+CUSTOM_CVAR(Int, vid_backend, 0, CVAR_ARCHIVE | CVAR_GLOBALCONFIG | CVAR_NOINITCALL)
+{
+	// [SP] This may seem pointless - but I don't want to implement live switching just
+	// yet - I'm pretty sure it's going to require a lot of reinits and destructions to
+	// do it right without memory leaks
+
+	Printf("Changing the video backend requires a restart for " GAMENAME ".\n");
+}
+
 CVAR(Int, vid_renderer, 1, 0)	// for some stupid mods which threw caution out of the window...
 
 
diff --git a/src/win32/hardware.cpp b/src/win32/hardware.cpp
index 75026ab36..22ccf999e 100644
--- a/src/win32/hardware.cpp
+++ b/src/win32/hardware.cpp
@@ -50,15 +50,7 @@
 #include "swrenderer/r_swrenderer.h"
 
 EXTERN_CVAR(Int, vid_maxfps)
-
-CUSTOM_CVAR(Int, vid_backend, 0, CVAR_ARCHIVE|CVAR_GLOBALCONFIG|CVAR_NOINITCALL)
-{
-	// [SP] This may seem pointless - but I don't want to implement live switching just
-	// yet - I'm pretty sure it's going to require a lot of reinits and destructions to
-	// do it right without memory leaks
-
-	Printf("Changing the video backend requires a restart for " GAMENAME ".\n");
-}
+EXTERN_CVAR(Int, vid_backend)
 
 extern HWND Window;