vk: revert -nort commit

`rt_force_disable` is perfectly fine, it just needs to be written into
either `vk.cfg` or `video.cfg` to work. Other configs are read *after*
`R_VkInit()` function get called.

ref/vk/NOTES.md

@@ -1,3 +1,9 @@
+# cvars
+## `rt_force_disable`
+On GPUs that support ray tracing forcefully disables it as if it wasn't supported at all. I.e. no RT extensions and modules are initialized. Useful for testing sometimes.
+Note: this cvar is read early in `R_VkInit()`, which gets executed before `autoexec.cfg`, `config.cfg`, etc are read. So putting it there will not work.
+`video.cfg` and `vk.cfg` are read before Vk initialization, so this cvar should go there.
+
 # Frame structure wrt calls from the engine
 - (eng) SCR_UpdateScreen()
 	- (eng) V_PreRender()

ref/vk/TODO.md

@@ -3,7 +3,7 @@
 - [ ] performance profiling and comparison
 
 ## 2024-04-12 E374
-- [x] `-vknort` arg to force-disable RT at init time
+- [x] ~~`-vknort` arg to force-disable RT at init time~~ -- reverted on 2024-04-29
 
 ## 2024-03-21 E372: agonizig over agenda
 ### Player-visible essentials and blockers. Big projects.

ref/vk/vk_core.c

@@ -41,6 +41,8 @@
 #include <string.h>
 #include <errno.h>
 
+#define LOG_MODULE core
+
 #define NULLINST_FUNCS(X) \
 	X(vkEnumerateInstanceVersion) \
 	X(vkCreateInstance) \
@@ -495,7 +497,7 @@ static void devicePrintMemoryInfo(const VkPhysicalDeviceMemoryProperties *props,
 	}
 }
 
-static qboolean createDevice( qboolean vk_no_rt ) {
+static qboolean createDevice( void ) {
 	void *head = NULL;
 	vk_available_device_t *available_devices;
 	const int num_available_devices = enumerateDevices( &available_devices );
@@ -518,8 +520,11 @@ static qboolean createDevice( qboolean vk_no_rt ) {
 			is_target_device_found = true;
 		}
 
-		if (candidate_device->ray_tracing && !vk_no_rt) {
-			vk_core.rtx = true;
+		if (candidate_device->ray_tracing) {
+			const qboolean force_disabled = CVAR_TO_BOOL(rt_force_disable);
+			if (force_disabled)
+				WARN("GPU[%d] supports ray tracing, but rt_force_disable is set, force-disabling ray tracing support", i);
+			vk_core.rtx = !force_disabled;
 		}
 
 		VkPhysicalDeviceAccelerationStructureFeaturesKHR accel_feature = {
@@ -729,8 +734,6 @@ qboolean R_VkInit( void )
 	vk_core.debug = vk_core.validate || !!(gEngine.Sys_CheckParm("-vkdebug") || gEngine.Sys_CheckParm("-gldebug"));
 	vk_core.rtx = false;
 
-	const qboolean vk_no_rt = gEngine.Sys_CheckParm("-vknort");
-
 	VK_LoadCvars();
 
 	// Force extremely verbose logs at startup.
@@ -785,7 +788,7 @@ qboolean R_VkInit( void )
 	}
 #endif
 
-	if (!createDevice(vk_no_rt))
+	if (!createDevice())
 		return false;
 
 	VK_LoadCvarsAfterInit();

ref/vk/vk_cvar.c

@@ -25,6 +25,7 @@ void VK_LoadCvars( void )
 	cl_lightstyle_lerping = gEngine.pfnGetCvarPointer( "cl_lightstyle_lerping", 0 );
 	r_lightmap = gEngine.Cvar_Get( "r_lightmap", "0", FCVAR_CHEAT, "lightmap debugging tool" );
 	r_infotool = gEngine.Cvar_Get( "r_infotool", "0", FCVAR_CHEAT, "DEBUG: print entity info under crosshair" );
+	rt_force_disable = gEngine.Cvar_Get( "rt_force_disable", "0", FCVAR_GLCONFIG, "Force disable Ray Tracing" );
 	vk_device_target_id = gEngine.Cvar_Get( "vk_device_target_id", "", FCVAR_GLCONFIG, "Selected video device id" );
 
 	vk_debug_log = gEngine.Cvar_Get("vk_debug_log_", "", FCVAR_GLCONFIG | FCVAR_READ_ONLY, "");

ref/vk/vk_cvar.h

@@ -23,6 +23,7 @@ void VK_LoadCvarsAfterInit( void );
 	X(vk_device_target_id) \
 	X(vk_debug_log) \
 	X(rt_capable) \
+	X(rt_force_disable) \
 	X(rt_enable) \
 	X(rt_bounces) \
 

ref/vk/vk_logs.h

@@ -3,6 +3,7 @@
 #include "vk_common.h"
 
 #define LIST_LOG_MODULES(X) \
+	X(core) \
 	X(misc) \
 	X(tex) \
 	X(brush) \