Added an OpenVR video driver (thanks @cnlohr!)

CMakeLists.txt

@@ -337,6 +337,7 @@ dep_option(SDL_VIVANTE             "Use Vivante EGL video driver" ON "${UNIX_SYS
 dep_option(SDL_VULKAN              "Enable Vulkan support" ON "SDL_VIDEO;ANDROID OR APPLE OR LINUX OR FREEBSD OR WINDOWS" OFF)
 dep_option(SDL_RENDER_VULKAN       "Enable the Vulkan render driver" ON "SDL_RENDER;SDL_VULKAN" OFF)
 dep_option(SDL_METAL               "Enable Metal support" ON "APPLE" OFF)
+set_option(SDL_OPENVR              "Use OpenVR video driver" OFF)
 dep_option(SDL_KMSDRM              "Use KMS DRM video driver" ${UNIX_SYS} "SDL_VIDEO" OFF)
 dep_option(SDL_KMSDRM_SHARED       "Dynamically load KMS DRM support" ON "SDL_KMSDRM" OFF)
 set_option(SDL_OFFSCREEN           "Use offscreen video driver" ON)
@@ -1544,6 +1545,7 @@ elseif(UNIX AND NOT APPLE AND NOT RISCOS AND NOT HAIKU)
     CheckOpenGL()
     CheckOpenGLES()
     CheckWayland()
+    CheckOpenVR()
     CheckVivante()
     CheckVulkan()
     CheckQNXScreen()

cmake/sdlchecks.cmake

@@ -662,6 +662,19 @@ macro(CheckVivante)
   endif()
 endmacro()
 
+# Requires:
+# - n/a
+macro(CheckOpenVR)
+  if(SDL_OPENVR)
+    set(HAVE_OPENVR TRUE)
+    set(HAVE_OPENVR_VIDEO TRUE)
+
+    sdl_glob_sources("${SDL3_SOURCE_DIR}/src/video/openvr/*.c")
+    set(SDL_VIDEO_DRIVER_OPENVR 1)
+    sdl_link_dependency(egl LIBS EGL)
+  endif()
+endmacro()
+
 # Requires:
 # - nada
 macro(CheckGLX)

include/SDL3/SDL_hints.h

@@ -2629,6 +2629,17 @@ extern "C" {
  */
 #define SDL_HINT_OPENGL_ES_DRIVER "SDL_OPENGL_ES_DRIVER"
 
+/**
+ *  Mechanism to specify openvr_api library location
+ *
+ *  By default, when using the OpenVR driver, it will search for the API
+ *  library in the current folder.  But, if you wish to use a system API
+ *  you can specify that by using this hint.  This should be the full or
+ *  relative path to a .dll on Windows or .so on Linux.
+ *
+ */
+#define SDL_HINT_OPENVR_LIBRARY              "SDL_OPENVR_LIBRARY"
+
 /**
  * A variable controlling which orientations are allowed on iOS/Android.
  *

include/SDL3/SDL_video.h

@@ -1282,6 +1282,11 @@ extern SDL_DECLSPEC SDL_Window * SDLCALL SDL_GetWindowParent(SDL_Window *window)
  * - `SDL_PROP_WINDOW_COCOA_METAL_VIEW_TAG_NUMBER`: the NSInteger tag
  *   assocated with metal views on the window
  *
+ * On OpenVR:
+ *
+ * - `SDL_PROP_WINDOW_OPENVR_OVERLAY_ID`: the OpenVR Overlay Handle ID for
+ *   the associated overlay window.
+ *
  * On Vivante:
  *
  * - `SDL_PROP_WINDOW_VIVANTE_DISPLAY_POINTER`: the EGLNativeDisplayType
@@ -1354,6 +1359,7 @@ extern SDL_DECLSPEC SDL_PropertiesID SDLCALL SDL_GetWindowProperties(SDL_Window
 #define SDL_PROP_WINDOW_KMSDRM_GBM_DEVICE_POINTER                   "SDL.window.kmsdrm.gbm_dev"
 #define SDL_PROP_WINDOW_COCOA_WINDOW_POINTER                        "SDL.window.cocoa.window"
 #define SDL_PROP_WINDOW_COCOA_METAL_VIEW_TAG_NUMBER                 "SDL.window.cocoa.metal_view_tag"
+#define SDL_PROP_WINDOW_OPENVR_OVERLAY_ID                           "SDL.window.openvr.overlay_id"
 #define SDL_PROP_WINDOW_VIVANTE_DISPLAY_POINTER                     "SDL.window.vivante.display"
 #define SDL_PROP_WINDOW_VIVANTE_WINDOW_POINTER                      "SDL.window.vivante.window"
 #define SDL_PROP_WINDOW_VIVANTE_SURFACE_POINTER                     "SDL.window.vivante.surface"

include/build_config/SDL_build_config.h.cmake

@@ -397,6 +397,7 @@
 #cmakedefine SDL_VIDEO_DRIVER_VITA @SDL_VIDEO_DRIVER_VITA@
 #cmakedefine SDL_VIDEO_DRIVER_VIVANTE @SDL_VIDEO_DRIVER_VIVANTE@
 #cmakedefine SDL_VIDEO_DRIVER_VIVANTE_VDK @SDL_VIDEO_DRIVER_VIVANTE_VDK@
+#cmakedefine SDL_VIDEO_DRIVER_OPENVR @SDL_VIDEO_DRIVER_OPENVR@
 #cmakedefine SDL_VIDEO_DRIVER_WAYLAND @SDL_VIDEO_DRIVER_WAYLAND@
 #cmakedefine SDL_VIDEO_DRIVER_WAYLAND_DYNAMIC @SDL_VIDEO_DRIVER_WAYLAND_DYNAMIC@
 #cmakedefine SDL_VIDEO_DRIVER_WAYLAND_DYNAMIC_CURSOR @SDL_VIDEO_DRIVER_WAYLAND_DYNAMIC_CURSOR@

src/video/SDL_sysvideo.h

@@ -521,6 +521,7 @@ extern VideoBootStrap Emscripten_bootstrap;
 extern VideoBootStrap OFFSCREEN_bootstrap;
 extern VideoBootStrap NGAGE_bootstrap;
 extern VideoBootStrap QNX_bootstrap;
+extern VideoBootStrap OPENVR_bootstrap;
 
 // Use SDL_OnVideoThread() sparingly, to avoid regressions in use cases that currently happen to work
 extern bool SDL_OnVideoThread(void);

src/video/SDL_video.c

@@ -139,6 +139,9 @@ static VideoBootStrap *bootstrap[] = {
 #ifdef SDL_INPUT_LINUXEV
     &DUMMY_evdev_bootstrap,
 #endif
+#endif
+#ifdef SDL_VIDEO_DRIVER_OPENVR
+    &OPENVR_bootstrap,
 #endif
     NULL
 };
@@ -2339,6 +2342,10 @@ SDL_Window *SDL_CreateWindowWithProperties(SDL_PropertiesID props)
         flags |= SDL_DefaultGraphicsBackends(_this);
     }
 
+#if defined(SDL_VIDEO_OPENGL) && defined(SDL_VIDEO_DRIVER_OPENVR)
+    flags |= SDL_WINDOW_OPENGL;
+#endif
+
     if (flags & SDL_WINDOW_OPENGL) {
         if (!_this->GL_CreateContext) {
             SDL_ContextNotSupported("OpenGL");

src/video/openvr/SDL_openvrvideo.h

@@ -0,0 +1,109 @@
+#ifndef _SDL_OPENVRVIDEO_H
+#define _SDL_OPENVRVIDEO_H
+
+#ifdef SDL_VIDEO_DRIVER_WINDOWS
+#ifdef EXTERN_C
+#undef EXTERN_C
+#endif
+#define GL_APIENTRY
+#define GL_APICALL
+#endif
+
+// OpenVR has a LOT of unused variables that GCC will freak out on.
+#ifdef __GNUC__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-variable"
+#endif
+
+#include "openvr_capi.h"
+
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif
+
+#include <stdint.h>
+
+#ifndef SDL_VIDEO_DRIVER_WINDOWS
+
+#include <GLES3/gl3.h>
+#include <GLES3/gl32.h>
+#include <EGL/egl.h>
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+#include <GLES2/gl2ext.h>
+
+#endif
+
+
+typedef struct SDL_WindowData
+{
+#ifdef SDL_VIDEO_DRIVER_WINDOWS
+    SDL_Window *window;
+    HWND hwnd;
+    HWND parent;
+    HDC hdc;
+    HDC mdc;
+#else
+    int dummy;
+#endif
+} SDL_WindowData;
+
+typedef struct SDL_VideoData {
+    void * openVRLIB;
+    intptr_t vrtoken;
+    intptr_t (*FN_VR_InitInternal)( EVRInitError *peError, EVRApplicationType eType );
+    const char *(*FN_VR_GetVRInitErrorAsEnglishDescription)( EVRInitError error );
+    intptr_t (*FN_VR_GetGenericInterface)( const char *pchInterfaceVersion, EVRInitError *peError );
+
+    int is_buffer_rendering;
+
+    unsigned int overlaytexture;
+
+    unsigned int fbo, rbo;
+
+    int saved_texture_state;
+
+    struct VR_IVRSystem_FnTable *oSystem;
+    struct VR_IVROverlay_FnTable *oOverlay;
+	struct VR_IVRInput_FnTable * oInput;
+	VROverlayHandle_t overlayID, thumbID, cursorID;
+	
+	char * sOverlayName;
+
+	VRActionSetHandle_t input_action_set;
+	VRActionHandle_t * input_action_handles_buttons;
+	int input_action_handles_buttons_count;
+	VRActionHandle_t * input_action_handles_axes;
+	int input_action_handles_axes_count;
+	VRActionHandle_t input_action_handles_haptics[2];
+
+    bool bKeyboardShown;
+    bool bHasShownOverlay;
+    int targw, targh;
+    int last_targw, last_targh;
+    int swap_interval;
+
+    bool bDidCreateOverlay;
+	bool renderdoc_debugmarker_frame_end;
+	bool bIconOverridden;
+	
+	SDL_Window * window;
+	
+	SDL_Joystick *virtual_joystick;
+#ifdef SDL_VIDEO_DRIVER_WINDOWS
+    HDC hdc;
+    HGLRC hglrc;
+#else
+    EGLDisplay eglDpy;
+    EGLContext eglCtx;
+#endif
+} SDL_VideoData;
+
+
+typedef struct SDL_DisplayData
+{
+    int dummy;
+} SDL_DisplayData;
+
+
+#endif