Added support for Oculus Rift CV1

src/core.c

@@ -9,6 +9,7 @@
 *       PLATFORM_ANDROID - Only OpenGL ES 2.0 devices
 *       PLATFORM_RPI - Rapsberry Pi (tested on Raspbian)
 *       PLATFORM_WEB - Emscripten, HTML5
+*       PLATFORM_OCULUS - Oculus Rift CV1 (with desktop mirror)
 *
 *   On PLATFORM_DESKTOP, the external lib GLFW3 (www.glfw.com) is used to manage graphic
 *   device, OpenGL context and input on multiple operating systems (Windows, Linux, OSX).
@@ -53,10 +54,18 @@
 #include <string.h>         // String function definitions, memset()
 #include <errno.h>          // Macros for reporting and retrieving error conditions through error codes
 
+#if defined(PLATFORM_OCULUS)
+    #define PLATFORM_DESKTOP    // Enable PLATFORM_DESKTOP code-base
+#endif
+
 #if defined(PLATFORM_DESKTOP)
     #include "glad.h"           // GLAD library: Manage OpenGL headers and extensions
 #endif
 
+#if defined(PLATFORM_OCULUS)
+    #include "../examples/oculus_glfw_sample/OculusSDK/LibOVR/Include/OVR_CAPI_GL.h"    // Oculus SDK for OpenGL
+#endif
+
 #if defined(PLATFORM_DESKTOP) || defined(PLATFORM_WEB)
     //#define GLFW_INCLUDE_NONE   // Disable the standard OpenGL header inclusion on GLFW3
     #include <GLFW/glfw3.h>       // GLFW3 library: Windows, OpenGL context and Input management
@@ -129,7 +138,31 @@
 //----------------------------------------------------------------------------------
 // Types and Structures Definition
 //----------------------------------------------------------------------------------
-// ...
+#if defined(PLATFORM_OCULUS)
+typedef struct OculusBuffer {
+    ovrTextureSwapChain textureChain;
+    GLuint depthId;
+    GLuint fboId;
+    int width;
+    int height;
+} OculusBuffer;
+
+typedef struct OculusMirror {
+    ovrMirrorTexture texture;
+    GLuint fboId;
+    int width;
+    int height;
+} OculusMirror;
+
+typedef struct OculusLayer {
+    ovrViewScaleDesc viewScaleDesc;
+    ovrLayerEyeFov eyeLayer;      // layer 0
+    //ovrLayerQuad quadLayer;     // TODO: layer 1: '2D' quad for GUI
+    Matrix eyeProjections[2];
+    int width;
+    int height;
+} OculusLayer;
+#endif
 
 //----------------------------------------------------------------------------------
 // Global Variables Definition
@@ -137,7 +170,9 @@
 #if defined(PLATFORM_DESKTOP) || defined(PLATFORM_WEB)
 static GLFWwindow *window;                      // Native window (graphic device)
 static bool windowMinimized = false;
-#elif defined(PLATFORM_ANDROID)
+#endif
+
+#if defined(PLATFORM_ANDROID)
 static struct android_app *app;                 // Android activity
 static struct android_poll_source *source;      // Android events polling source
 static int ident, events;                       // Android ALooper_pollAll() variables
@@ -149,7 +184,9 @@ static bool contextRebindRequired = false;      // Used to know context rebind r
 
 static int previousButtonState[128] = { 1 };    // Required to check if button pressed/released once
 static int currentButtonState[128] = { 1 };     // Required to check if button pressed/released once
-#elif defined(PLATFORM_RPI)
+#endif
+
+#if defined(PLATFORM_RPI)
 static EGL_DISPMANX_WINDOW_T nativeWindow;      // Native window (graphic device)
 
 // Keyboard input variables
@@ -180,6 +217,17 @@ static uint64_t baseTime;                   // Base time measure for hi-res time
 static bool windowShouldClose = false;      // Flag to set window for closing
 #endif
 
+#if defined(PLATFORM_OCULUS)
+// OVR device variables
+static ovrSession session;
+static ovrHmdDesc hmdDesc;
+static ovrGraphicsLuid luid;
+static OculusLayer layer;
+static OculusBuffer buffer;
+static OculusMirror mirror;
+static unsigned int frameIndex = 0;
+#endif
+
 static unsigned int displayWidth, displayHeight;     // Display width and height (monitor, device-screen, LCD, ...)
 static int screenWidth, screenHeight;       // Screen width and height (used render area)
 static int renderWidth, renderHeight;       // Framebuffer width and height (render area)
@@ -189,6 +237,7 @@ static int renderOffsetX = 0;               // Offset X from render area (must b
 static int renderOffsetY = 0;               // Offset Y from render area (must be divided by 2)
 static bool fullscreen = false;             // Fullscreen mode (useful only for PLATFORM_DESKTOP)
 static Matrix downscaleView;                // Matrix to downscale view (in case screen size bigger than display size)
+static Matrix cameraView;                   // Store camera view matrix (required for Oculus Rift)
 
 #if defined(PLATFORM_DESKTOP) || defined(PLATFORM_RPI) || defined(PLATFORM_WEB)
 static const char *windowTitle;             // Window text title...
@@ -287,6 +336,19 @@ static void InitGamepad(void);                          // Init raw gamepad inpu
 static void *GamepadThread(void *arg);                  // Mouse reading thread
 #endif
 
+#if defined(PLATFORM_OCULUS)
+// Oculus Rift functions
+static Matrix FromOvrMatrix(ovrMatrix4f ovrM);
+static OculusBuffer LoadOculusBuffer(ovrSession session, int width, int height);
+static void UnloadOculusBuffer(ovrSession session, OculusBuffer buffer);
+static void SetOculusBuffer(ovrSession session, OculusBuffer buffer);
+static void UnsetOculusBuffer(OculusBuffer buffer);
+static OculusMirror LoadOculusMirror(ovrSession session, int width, int height);    // Load Oculus mirror buffers
+static void UnloadOculusMirror(ovrSession session, OculusMirror mirror);            // Unload Oculus mirror buffers
+static void BlitOculusMirror(ovrSession session, OculusMirror mirror);
+static OculusLayer InitOculusLayer(ovrSession session);
+#endif
+
 //----------------------------------------------------------------------------------
 // Module Functions Definition - Window and OpenGL Context Functions
 //----------------------------------------------------------------------------------
@@ -335,6 +397,11 @@ void InitWindow(int width, int height, const char *title)
     //emscripten_set_gamepaddisconnected_callback(NULL, 1, EmscriptenInputCallback);
 #endif
 
+#if defined(PLATFORM_OCULUS)
+    // Recenter OVR tracking origin
+    ovr_RecenterTrackingOrigin(session);
+#endif
+
     mousePosition.x = (float)screenWidth/2.0f;
     mousePosition.y = (float)screenHeight/2.0f;
 
@@ -345,8 +412,9 @@ void InitWindow(int width, int height, const char *title)
         LogoAnimation();
     }
 }
+#endif
 
-#elif defined(PLATFORM_ANDROID)
+#if defined(PLATFORM_ANDROID)
 // Android activity initialization
 void InitWindow(int width, int height, struct android_app *state)
 {
@@ -415,12 +483,19 @@ void CloseWindow(void)
 {
     UnloadDefaultFont();
 
+#if defined(PLATFORM_OCULUS)
+    UnloadOculusMirror(session, mirror);    // Unload Oculus mirror buffer
+    UnloadOculusBuffer(session, buffer);    // Unload Oculus texture buffers
+#endif
+
     rlglClose();                // De-init rlgl
 
 #if defined(PLATFORM_DESKTOP) || defined(PLATFORM_WEB)
     glfwDestroyWindow(window);
     glfwTerminate();
-#elif defined(PLATFORM_ANDROID) || defined(PLATFORM_RPI)
+#endif
+
+#if defined(PLATFORM_ANDROID) || defined(PLATFORM_RPI)
     // Close surface, context and display
     if (display != EGL_NO_DISPLAY)
     {
@@ -443,6 +518,11 @@ void CloseWindow(void)
     }
 #endif
 
+#if defined(PLATFORM_OCULUS)
+    ovr_Destroy(session);   // Must be called after glfwTerminate()
+    ovr_Shutdown();
+#endif
+
     TraceLog(INFO, "Window closed successfully");
 }
 
@@ -454,7 +534,9 @@ bool WindowShouldClose(void)
     while (windowMinimized) glfwPollEvents();
 
     return (glfwWindowShouldClose(window));
-#elif defined(PLATFORM_ANDROID) || defined(PLATFORM_RPI)
+#endif
+
+#if defined(PLATFORM_ANDROID) || defined(PLATFORM_RPI)
     return windowShouldClose;
 #endif
 }
@@ -480,7 +562,9 @@ void ToggleFullscreen(void)
     glfwDestroyWindow(window);         // Destroy the current window (we will recreate it!)
 
     InitWindow(screenWidth, screenHeight, windowTitle);
-#elif defined(PLATFORM_ANDROID) || defined(PLATFORM_RPI)
+#endif
+
+#if defined(PLATFORM_ANDROID) || defined(PLATFORM_RPI)
     TraceLog(WARNING, "Could not toggle to windowed mode");
 #endif
 }
@@ -511,6 +595,18 @@ void BeginDrawing(void)
     updateTime = currentTime - previousTime;
     previousTime = currentTime;
     
+#if defined(PLATFORM_OCULUS)
+    frameIndex++;
+   
+    ovrPosef eyePoses[2];
+    ovr_GetEyePoses(session, frameIndex, ovrTrue, layer.viewScaleDesc.HmdToEyeOffset, eyePoses, &layer.eyeLayer.SensorSampleTime);
+    
+    layer.eyeLayer.RenderPose[0] = eyePoses[0];
+    layer.eyeLayer.RenderPose[1] = eyePoses[1];
+    
+    SetOculusBuffer(session, buffer);
+#endif
+
     rlClearScreenBuffers();             // Clear current framebuffers
     rlLoadIdentity();                   // Reset current matrix (MODELVIEW)
     rlMultMatrixf(MatrixToFloat(downscaleView));       // If downscale required, apply it here
@@ -522,10 +618,51 @@ void BeginDrawing(void)
 // End canvas drawing and Swap Buffers (Double Buffering)
 void EndDrawing(void)
 {
-    rlglDraw();                     // Draw Buffers (Only OpenGL 3+ and ES2)
+#if defined(PLATFORM_OCULUS)
+    for (int eye = 0; eye < 2; eye++)
+    {
+        rlViewport(layer.eyeLayer.Viewport[eye].Pos.x, layer.eyeLayer.Viewport[eye].Pos.y, layer.eyeLayer.Viewport[eye].Size.w, layer.eyeLayer.Viewport[eye].Size.h);
+
+        Quaternion eyeRPose = (Quaternion){ layer.eyeLayer.RenderPose[eye].Orientation.x, 
+                                            layer.eyeLayer.RenderPose[eye].Orientation.y, 
+                                            layer.eyeLayer.RenderPose[eye].Orientation.z, 
+                                            layer.eyeLayer.RenderPose[eye].Orientation.w };
+        QuaternionInvert(&eyeRPose);
+        Matrix eyeOrientation = QuaternionToMatrix(eyeRPose);
+        Matrix eyeTranslation = MatrixTranslate(-layer.eyeLayer.RenderPose[eye].Position.x, 
+                                                -layer.eyeLayer.RenderPose[eye].Position.y, 
+                                                -layer.eyeLayer.RenderPose[eye].Position.z);
+
+        Matrix eyeView = MatrixMultiply(eyeTranslation, eyeOrientation);
+        Matrix modelEyeView = MatrixMultiply(cameraView, eyeView);  // Using internal camera modelview matrix
+
+        SetMatrixModelview(modelEyeView);
+        SetMatrixProjection(layer.eyeProjections[eye]);
+#endif
+    
+        rlglDraw();                     // Draw Buffers (Only OpenGL 3+ and ES2)
+
+#if defined(PLATFORM_OCULUS)
+    }
+    
+    UnsetOculusBuffer(buffer);
+    
+    ovr_CommitTextureSwapChain(session, buffer.textureChain);
+    
+    ovrLayerHeader *layers = &layer.eyeLayer.Header;
+    ovr_SubmitFrame(session, frameIndex, &layer.viewScaleDesc, &layers, 1);
+
+    // Blit mirror texture to back buffer
+    BlitOculusMirror(session, mirror);
+
+    // Get session status information
+    ovrSessionStatus sessionStatus;
+    ovr_GetSessionStatus(session, &sessionStatus);
+    if (sessionStatus.ShouldQuit) TraceLog(WARNING, "OVR: Session should quit...");
+    if (sessionStatus.ShouldRecenter) ovr_RecenterTrackingOrigin(session);
+#endif
 
     SwapBuffers();                  // Copy back buffer to front buffer
-
     PollInputEvents();              // Poll user events
     
     // Frame time control system
@@ -595,8 +732,8 @@ void Begin3dMode(Camera camera)
     rlLoadIdentity();                   // Reset current matrix (MODELVIEW)
 
     // Setup Camera view
-    Matrix matView = MatrixLookAt(camera.position, camera.target, camera.up);
+    cameraView = MatrixLookAt(camera.position, camera.target, camera.up);
-    rlMultMatrixf(MatrixToFloat(matView));      // Multiply MODELVIEW matrix by view matrix (camera)
+    rlMultMatrixf(MatrixToFloat(cameraView));      // Multiply MODELVIEW matrix by view matrix (camera)
     
     rlEnableDepthTest();                // Enable DEPTH_TEST for 3D
 }
@@ -1437,6 +1574,30 @@ static void InitDisplay(int width, int height)
     // Downscale matrix is required in case desired screen area is bigger than display area
     downscaleView = MatrixIdentity();
     
+#if defined(PLATFORM_OCULUS)
+    ovrResult result = ovr_Initialize(NULL);
+    if (OVR_FAILURE(result)) TraceLog(ERROR, "OVR: Could not initialize Oculus device");
+
+    result = ovr_Create(&session, &luid);
+    if (OVR_FAILURE(result))
+    {
+        TraceLog(WARNING, "OVR: Could not create Oculus session");
+        ovr_Shutdown();
+    }
+
+    hmdDesc = ovr_GetHmdDesc(session);
+    
+    TraceLog(INFO, "OVR: Product Name: %s", hmdDesc.ProductName);
+    TraceLog(INFO, "OVR: Manufacturer: %s", hmdDesc.Manufacturer);
+    TraceLog(INFO, "OVR: Product ID: %i", hmdDesc.ProductId);
+    TraceLog(INFO, "OVR: Product Type: %i", hmdDesc.Type);
+    TraceLog(INFO, "OVR: Serian Number: %s", hmdDesc.SerialNumber);
+    TraceLog(INFO, "OVR: Resolution: %ix%i", hmdDesc.Resolution.w, hmdDesc.Resolution.h);
+    
+    screenWidth = hmdDesc.Resolution.w/2;
+    screenHeight = hmdDesc.Resolution.h/2;
+#endif
+    
 #if defined(PLATFORM_DESKTOP) || defined(PLATFORM_WEB)
     glfwSetErrorCallback(ErrorCallback);
 
@@ -1565,14 +1726,17 @@ static void InitDisplay(int width, int height)
 #endif
 
     glfwMakeContextCurrent(window);
+#if defined(PLATFORM_OCULUS)
+    glfwSwapInterval(0);
+#endif
 
 #if defined(PLATFORM_DESKTOP)
-    // Extensions initialization for OpenGL 3.3
+    // Load OpenGL 3.3 extensions using GLAD
     if (rlGetVersion() == OPENGL_33)
     {
-        // NOTE: glad is generated and contains only required OpenGL version and Core extensions
+        // NOTE: glad is generated and contains only required OpenGL 3.3 Core extensions
-        //if (!gladLoadGL()) TraceLog(ERROR, "Failed to initialize glad\n");
+        if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) TraceLog(WARNING, "GLAD: Cannot load OpenGL extensions");
-        if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) TraceLog(ERROR, "Failed to initialize glad\n"); // No GLFW3 in this module...
+        else TraceLog(INFO, "GLAD: OpenGL extensions loaded successfully");
 
         if (GLAD_GL_VERSION_3_3) TraceLog(INFO, "OpenGL 3.3 Core profile supported");
         else TraceLog(ERROR, "OpenGL 3.3 Core profile not supported");
@@ -1746,13 +1910,16 @@ static void InitDisplay(int width, int height)
 static void InitGraphics(void)
 {
     rlglInit();                     // Init rlgl
+    rlglInitGraphics(renderOffsetX, renderOffsetY, renderWidth, renderHeight);  // Init graphics (OpenGL stuff)
 
 #if defined(PLATFORM_OCULUS)
-    //rlglInitOculus();             // Init rlgl for Oculus Rift (required textures)
+    // Initialize Oculus Buffers
+    layer = InitOculusLayer(session);   
+    buffer = LoadOculusBuffer(session, layer.width, layer.height);
+    mirror = LoadOculusMirror(session, hmdDesc.Resolution.w/2, hmdDesc.Resolution.h/2);
+    layer.eyeLayer.ColorTexture[0] = buffer.textureChain;     //SetOculusLayerTexture(eyeLayer, buffer.textureChain);
 #endif
 
-    rlglInitGraphics(renderOffsetX, renderOffsetY, renderWidth, renderHeight);  // Init graphics (OpenGL stuff)
-
     ClearBackground(RAYWHITE);      // Default background color for raylib games :P
 
 #if defined(PLATFORM_ANDROID)
@@ -1860,7 +2027,9 @@ static double GetTime(void)
 {
 #if defined(PLATFORM_DESKTOP) || defined(PLATFORM_WEB)
     return glfwGetTime();
-#elif defined(PLATFORM_ANDROID) || defined(PLATFORM_RPI)
+#endif
+
+#if defined(PLATFORM_ANDROID) || defined(PLATFORM_RPI)
     struct timespec ts;
     clock_gettime(CLOCK_MONOTONIC, &ts);
     uint64_t time = (uint64_t)ts.tv_sec*1000000000LLU + (uint64_t)ts.tv_nsec;
@@ -1928,8 +2097,9 @@ static void PollInputEvents(void)
     currentMouseWheelY = 0;
 
     glfwPollEvents();       // Register keyboard/mouse events... and window events!
-#elif defined(PLATFORM_ANDROID)
+#endif
 
+#if defined(PLATFORM_ANDROID)
     // Register previous keys states
     for (int i = 0; i < 128; i++) previousButtonState[i] = currentButtonState[i];
 
@@ -1948,8 +2118,9 @@ static void PollInputEvents(void)
             //ANativeActivity_finish(app->activity);
         }
     }
-#elif defined(PLATFORM_RPI)
+#endif
 
+#if defined(PLATFORM_RPI)
     // NOTE: Mouse input events polling is done asynchonously in another pthread - MouseThread()
 
     // NOTE: Keyboard reading could be done using input_event(s) reading or just read from stdin,
@@ -1957,7 +2128,6 @@ static void PollInputEvents(void)
     ProcessKeyboard();
 
     // NOTE: Gamepad (Joystick) input events polling is done asynchonously in another pthread - GamepadThread()
-
 #endif
 }
 
@@ -1966,7 +2136,9 @@ static void SwapBuffers(void)
 {
 #if defined(PLATFORM_DESKTOP) || defined(PLATFORM_WEB)
     glfwSwapBuffers(window);
-#elif defined(PLATFORM_ANDROID) || defined(PLATFORM_RPI)
+#endif
+
+#if defined(PLATFORM_ANDROID) || defined(PLATFORM_RPI)
     eglSwapBuffers(display, surface);
 #endif
 }
@@ -2774,6 +2946,214 @@ static void *GamepadThread(void *arg)
 }
 #endif
 
+
+#if defined(PLATFORM_OCULUS)
+// Convert from Oculus ovrMatrix4f struct to raymath Matrix struct
+static Matrix FromOvrMatrix(ovrMatrix4f ovrmat)
+{
+    Matrix rmat;
+    
+    rmat.m0 = ovrmat.M[0][0];
+    rmat.m1 = ovrmat.M[1][0];
+    rmat.m2 = ovrmat.M[2][0];
+    rmat.m3 = ovrmat.M[3][0];
+    rmat.m4 = ovrmat.M[0][1];
+    rmat.m5 = ovrmat.M[1][1];
+    rmat.m6 = ovrmat.M[2][1];
+    rmat.m7 = ovrmat.M[3][1];
+    rmat.m8 = ovrmat.M[0][2];
+    rmat.m9 = ovrmat.M[1][2];
+    rmat.m10 = ovrmat.M[2][2];
+    rmat.m11 = ovrmat.M[3][2];
+    rmat.m12 = ovrmat.M[0][3];
+    rmat.m13 = ovrmat.M[1][3];
+    rmat.m14 = ovrmat.M[2][3];
+    rmat.m15 = ovrmat.M[3][3];
+    
+    MatrixTranspose(&rmat);
+    
+    return rmat;
+}
+
+// Load Oculus required buffers: texture-swap-chain, fbo, texture-depth
+static OculusBuffer LoadOculusBuffer(ovrSession session, int width, int height)
+{
+    OculusBuffer buffer;
+    buffer.width = width;
+    buffer.height = height;
+    
+    // Create OVR texture chain
+    ovrTextureSwapChainDesc desc = {};
+    desc.Type = ovrTexture_2D;
+    desc.ArraySize = 1;
+    desc.Width = width;
+    desc.Height = height;
+    desc.MipLevels = 1;
+    desc.Format = OVR_FORMAT_R8G8B8A8_UNORM_SRGB;   // Requires glEnable(GL_FRAMEBUFFER_SRGB);
+    desc.SampleCount = 1;
+    desc.StaticImage = ovrFalse;
+
+    ovrResult result = ovr_CreateTextureSwapChainGL(session, &desc, &buffer.textureChain);
+    
+    if (!OVR_SUCCESS(result)) TraceLog(WARNING, "OVR: Failed to create swap textures buffer");
+
+    int textureCount = 0;
+    ovr_GetTextureSwapChainLength(session, buffer.textureChain, &textureCount);
+    
+    if (!OVR_SUCCESS(result) || !textureCount) TraceLog(WARNING, "OVR: Unable to count swap chain textures");
+
+    for (int i = 0; i < textureCount; ++i)
+    {
+        GLuint chainTexId;
+        ovr_GetTextureSwapChainBufferGL(session, buffer.textureChain, i, &chainTexId);
+        glBindTexture(GL_TEXTURE_2D, chainTexId);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    }
+    
+    glBindTexture(GL_TEXTURE_2D, 0);
+    
+    /*
+    // Setup framebuffer object (using depth texture)
+    glGenFramebuffers(1, &buffer.fboId);
+    glGenTextures(1, &buffer.depthId);
+    glBindTexture(GL_TEXTURE_2D, buffer.depthId);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT16, buffer.width, buffer.height, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_INT, NULL);
+    */
+    
+    // Setup framebuffer object (using depth renderbuffer)
+    glGenFramebuffers(1, &buffer.fboId);
+    glGenRenderbuffers(1, &buffer.depthId);
+    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, buffer.fboId);
+    glBindRenderbuffer(GL_RENDERBUFFER, buffer.depthId);
+    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, buffer.width, buffer.height);
+    glBindRenderbuffer(GL_RENDERBUFFER, 0);
+    glFramebufferRenderbuffer(GL_DRAW_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, buffer.depthId);
+    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
+
+    return buffer;
+}
+
+// Unload texture required buffers
+static void UnloadOculusBuffer(ovrSession session, OculusBuffer buffer)
+{
+    if (buffer.textureChain)
+    {
+        ovr_DestroyTextureSwapChain(session, buffer.textureChain);
+        buffer.textureChain = NULL;
+    }
+
+    if (buffer.depthId != 0) glDeleteTextures(1, &buffer.depthId);
+    if (buffer.fboId != 0) glDeleteFramebuffers(1, &buffer.fboId);
+}
+
+// Set current Oculus buffer
+static void SetOculusBuffer(ovrSession session, OculusBuffer buffer)
+{
+    GLuint currentTexId;
+    int currentIndex;
+    
+    ovr_GetTextureSwapChainCurrentIndex(session, buffer.textureChain, &currentIndex);
+    ovr_GetTextureSwapChainBufferGL(session, buffer.textureChain, currentIndex, &currentTexId);
+
+    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, buffer.fboId);
+    glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, currentTexId, 0);
+    //glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, buffer.depthId, 0);    // Already binded
+
+    //glViewport(0, 0, buffer.width, buffer.height);        // Useful if rendering to separate framebuffers (every eye)
+    //glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+    
+    // Required if OculusBuffer format is OVR_FORMAT_R8G8B8A8_UNORM_SRGB
+    glEnable(GL_FRAMEBUFFER_SRGB);
+}
+
+// Unset Oculus buffer
+static void UnsetOculusBuffer(OculusBuffer buffer)
+{
+    glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, 0, 0);
+    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
+}
+
+// Load Oculus mirror buffers
+static OculusMirror LoadOculusMirror(ovrSession session, int width, int height)
+{
+    OculusMirror mirror;
+    mirror.width = width;
+    mirror.height = height;
+    
+    ovrMirrorTextureDesc mirrorDesc;
+    memset(&mirrorDesc, 0, sizeof(mirrorDesc));
+    mirrorDesc.Format = OVR_FORMAT_R8G8B8A8_UNORM_SRGB;
+    mirrorDesc.Width = mirror.width;
+    mirrorDesc.Height = mirror.height;
+    
+    if (!OVR_SUCCESS(ovr_CreateMirrorTextureGL(session, &mirrorDesc, &mirror.texture))) TraceLog(WARNING, "Could not create mirror texture");
+
+    glGenFramebuffers(1, &mirror.fboId);
+
+    return mirror;
+}
+
+// Unload Oculus mirror buffers
+static void UnloadOculusMirror(ovrSession session, OculusMirror mirror)
+{
+    if (mirror.fboId != 0) glDeleteFramebuffers(1, &mirror.fboId);
+    if (mirror.texture) ovr_DestroyMirrorTexture(session, mirror.texture);
+}
+
+static void BlitOculusMirror(ovrSession session, OculusMirror mirror)
+{
+    GLuint mirrorTextureId;
+    
+    ovr_GetMirrorTextureBufferGL(session, mirror.texture, &mirrorTextureId);
+    
+    glBindFramebuffer(GL_READ_FRAMEBUFFER, mirror.fboId);
+    glFramebufferTexture2D(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mirrorTextureId, 0);
+    glBlitFramebuffer(0, 0, mirror.width, mirror.height, 0, mirror.height, mirror.width, 0, GL_COLOR_BUFFER_BIT, GL_NEAREST);
+    glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);
+}
+
+// Requires: session, hmdDesc
+static OculusLayer InitOculusLayer(ovrSession session)
+{
+    OculusLayer layer = { 0 };
+    
+    layer.viewScaleDesc.HmdSpaceToWorldScaleInMeters = 1.0f;
+
+    memset(&layer.eyeLayer, 0, sizeof(ovrLayerEyeFov));
+    layer.eyeLayer.Header.Type = ovrLayerType_EyeFov;
+    layer.eyeLayer.Header.Flags = ovrLayerFlag_TextureOriginAtBottomLeft;
+
+    ovrEyeRenderDesc eyeRenderDescs[2];
+    
+    for (int eye = 0; eye < 2; eye++)
+    {
+        eyeRenderDescs[eye] = ovr_GetRenderDesc(session, eye, hmdDesc.DefaultEyeFov[eye]);
+        ovrMatrix4f ovrPerspectiveProjection = ovrMatrix4f_Projection(eyeRenderDescs[eye].Fov, 0.01f, 10000.0f, ovrProjection_None); //ovrProjection_ClipRangeOpenGL);
+        layer.eyeProjections[eye] = FromOvrMatrix(ovrPerspectiveProjection);      // NOTE: struct ovrMatrix4f { float M[4][4] } --> struct Matrix
+
+        layer.viewScaleDesc.HmdToEyeOffset[eye] = eyeRenderDescs[eye].HmdToEyeOffset;
+        layer.eyeLayer.Fov[eye] = eyeRenderDescs[eye].Fov;
+        
+        ovrSizei eyeSize = ovr_GetFovTextureSize(session, eye, layer.eyeLayer.Fov[eye], 1.0f);
+        layer.eyeLayer.Viewport[eye].Size = eyeSize;
+        layer.eyeLayer.Viewport[eye].Pos.x = layer.width;
+        layer.eyeLayer.Viewport[eye].Pos.y = 0;
+
+        layer.height = eyeSize.h;     //std::max(renderTargetSize.y, (uint32_t)eyeSize.h);
+        layer.width += eyeSize.w;
+    }
+    
+    return layer;
+}
+#endif
+
 // Plays raylib logo appearing animation
 static void LogoAnimation(void)
 {