Oculus Rift SDL2 OpenGL Demo

#define GLEW_STATIC
#include "GL/glew.h"
// Uncomment your platform
//#define OVR_OS_WIN32
//#define OVR_OS_MAC
//#define OVR_OS_LINUX
#include "OVR_CAPI_GL.h"
#include "Kernel/OVR_Math.h"
#include "SDL.h"
#include "SDL_syswm.h"

using namespace OVR;

int main(int argc, char *argv[])
{
    SDL_Init(SDL_INIT_VIDEO);

    int x = SDL_WINDOWPOS_CENTERED;
    int y = SDL_WINDOWPOS_CENTERED;
    Uint32 flags = SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN;

    bool debug = false;

    ovr_Initialize();

    ovrHmd hmd = ovrHmd_Create(0);

    if (hmd == NULL)
    {
        hmd = ovrHmd_CreateDebug(ovrHmd_DK1);

        debug = true;
    }

    ovrHmdDesc hmdDesc;

    ovrHmd_GetDesc(hmd, &hmdDesc);

    if (debug == false)
    {
        x = hmdDesc.WindowsPos.x;
        y = hmdDesc.WindowsPos.y;
        flags |= SDL_WINDOW_FULLSCREEN_DESKTOP;
    }

    int w = hmdDesc.Resolution.w;
    int h = hmdDesc.Resolution.h;

    SDL_Window *window = SDL_CreateWindow("Oculus Rift SDL2 OpenGL Demo", x, y, w, h, flags);

    SDL_GLContext context = SDL_GL_CreateContext(window);

    glewExperimental = GL_TRUE;

    glewInit();

    Sizei recommendedTex0Size = ovrHmd_GetFovTextureSize(hmd, ovrEye_Left, hmdDesc.DefaultEyeFov[0], 1.0f);
    Sizei recommendedTex1Size = ovrHmd_GetFovTextureSize(hmd, ovrEye_Right, hmdDesc.DefaultEyeFov[1], 1.0f);
    Sizei renderTargetSize;
    renderTargetSize.w = recommendedTex0Size.w + recommendedTex1Size.w;
    renderTargetSize.h = max(recommendedTex0Size.h, recommendedTex1Size.h);

    GLuint frameBuffer;
    glGenFramebuffers(1, &frameBuffer);

    GLuint texture;
    glGenTextures(1, &texture);

    glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);
    glBindTexture(GL_TEXTURE_2D, texture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, renderTargetSize.w, renderTargetSize.h, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, texture, 0);

    GLuint renderBuffer;
    glGenRenderbuffers(1, &renderBuffer);
    glBindRenderbuffer(GL_RENDERBUFFER, renderBuffer);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, renderTargetSize.w, renderTargetSize.h);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, renderBuffer);

    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
    {
        glDeleteFramebuffers(1, &frameBuffer);
        glDeleteTextures(1, &texture);
        glDeleteRenderbuffers(1, &renderBuffer);

        SDL_GL_DeleteContext(context);

        SDL_DestroyWindow(window);

        ovrHmd_Destroy(hmd);

        ovr_Shutdown();

        SDL_Quit();

        return 0;
    }

    ovrFovPort eyeFov[2] = { hmdDesc.DefaultEyeFov[0], hmdDesc.DefaultEyeFov[1] };

    ovrRecti eyeRenderViewport[2];
    eyeRenderViewport[0].Pos = Vector2i(0, 0);
    eyeRenderViewport[0].Size = Sizei(renderTargetSize.w / 2, renderTargetSize.h);
    eyeRenderViewport[1].Pos = Vector2i((renderTargetSize.w + 1) / 2, 0);
    eyeRenderViewport[1].Size = eyeRenderViewport[0].Size;

    ovrGLTexture eyeTexture[2];
    eyeTexture[0].OGL.Header.API = ovrRenderAPI_OpenGL;
    eyeTexture[0].OGL.Header.TextureSize = renderTargetSize;
    eyeTexture[0].OGL.Header.RenderViewport = eyeRenderViewport[0];
    eyeTexture[0].OGL.TexId = texture;

    eyeTexture[1] = eyeTexture[0];
    eyeTexture[1].OGL.Header.RenderViewport = eyeRenderViewport[1];

    SDL_SysWMinfo info;

    SDL_VERSION(&info.version);

    SDL_GetWindowWMInfo(window, &info);

    ovrGLConfig cfg;
    cfg.OGL.Header.API = ovrRenderAPI_OpenGL;
    cfg.OGL.Header.RTSize = Sizei(hmdDesc.Resolution.w, hmdDesc.Resolution.h);
    cfg.OGL.Header.Multisample = 1;
#if defined(OVR_OS_WIN32)
    cfg.OGL.Window = info.info.win.window;
#elif defined(OVR_OS_LINUX)
    cfg.OGL.Disp = info.info.x11.display;
    cfg.OGL.Win = info.info.x11.window;
#endif

    ovrEyeRenderDesc eyeRenderDesc[2];

    ovrHmd_ConfigureRendering(hmd, &cfg.Config, ovrDistortionCap_Chromatic | ovrDistortionCap_TimeWarp, eyeFov, eyeRenderDesc);

    ovrHmd_SetEnabledCaps(hmd, ovrHmdCap_LowPersistence | ovrHmdCap_LatencyTest);

    ovrHmd_StartSensor(hmd, ovrSensorCap_Orientation | ovrSensorCap_YawCorrection | ovrSensorCap_Position, 0);

    const GLchar *vertexShaderSource[] = {
        "#version 150\n"
        "uniform mat4 MVPMatrix;\n"
        "in vec3 position;\n"
        "void main()\n"
        "{\n"
        "    gl_Position = MVPMatrix * vec4(position, 1.0);\n"
        "}"
    };

    GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, vertexShaderSource, 0);
    glCompileShader(vertexShader);

    const GLchar *fragmentShaderSource[] = {
        "#version 150\n"
        "out vec4 outputColor;\n"
        "void main()\n"
        "{\n"
        "    outputColor = vec4(1.0, 0.0, 0.0, 1.0);\n"
        "}"
    };

    GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, fragmentShaderSource, 0);
    glCompileShader(fragmentShader);

    GLuint program = glCreateProgram();
    glAttachShader(program, vertexShader);
    glAttachShader(program, fragmentShader);
    glLinkProgram(program);
    glUseProgram(program);

    GLuint MVPMatrixLocation = glGetUniformLocation(program, "MVPMatrix");
    GLuint positionLocation = glGetAttribLocation(program, "position");

    GLuint vertexArray;
    glGenVertexArrays(1, &vertexArray);
    glBindVertexArray(vertexArray);

    GLfloat vertices[] = {
        0.0f, 1.0f, -2.0f,
        -1.0f, -1.0f, -2.0f,
        1.0f, -1.0f, -2.0f
    };

    GLuint positionBuffer;
    glGenBuffers(1, &positionBuffer);
    glBindBuffer(GL_ARRAY_BUFFER, positionBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
    glVertexAttribPointer(positionLocation, 3, GL_FLOAT, GL_FALSE, 0, 0);
    glEnableVertexAttribArray(positionLocation);

    glClearColor(0.0f, 0.0f, 1.0f, 1.0f);
    glClearDepth(1.0f);

    glDepthFunc(GL_LEQUAL);
    glEnable(GL_DEPTH_TEST);

    bool running = true;

    while (running)
    {
        SDL_Event event;

        while (SDL_PollEvent(&event))
        {
            switch (event.type)
            {
            case SDL_QUIT:
                running = false;
            case SDL_KEYDOWN:
                switch (event.key.keysym.sym)
                {
                case SDLK_ESCAPE:
                    running = false;
                    break;
                default:
                    break;
                }
                break;
            default:
                break;
            }
        }

        ovrFrameTiming frameTiming = ovrHmd_BeginFrame(hmd, 0);

        glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);

        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        ovrPosef eyeRenderPose[2];

        for (int eyeIndex = 0; eyeIndex < ovrEye_Count; eyeIndex++)
        {
            ovrEyeType eye = hmdDesc.EyeRenderOrder[eyeIndex];
            eyeRenderPose[eye] = ovrHmd_BeginEyeRender(hmd, eye);

            Matrix4f MVPMatrix = Matrix4f(ovrMatrix4f_Projection(eyeRenderDesc[eye].Fov, 0.01f, 10000.0f, true)) * Matrix4f::Translation(eyeRenderDesc[eye].ViewAdjust) * Matrix4f(Quatf(eyeRenderPose[eye].Orientation).Inverted());

            glUniformMatrix4fv(MVPMatrixLocation, 1, GL_FALSE, &MVPMatrix.Transposed().M[0][0]);

            glViewport(eyeRenderViewport[eye].Pos.x, eyeRenderViewport[eye].Pos.y, eyeRenderViewport[eye].Size.w, eyeRenderViewport[eye].Size.h);

            glDrawArrays(GL_TRIANGLES, 0, 3);

            ovrHmd_EndEyeRender(hmd, eye, eyeRenderPose[eye], &eyeTexture[eye].Texture);
        }

        ovrHmd_EndFrame(hmd);
    }

    glDeleteVertexArrays(1, &vertexArray);
    glDeleteBuffers(1, &positionBuffer);

    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);
    glDeleteProgram(program);

    glDeleteFramebuffers(1, &frameBuffer);
    glDeleteTextures(1, &texture);
    glDeleteRenderbuffers(1, &renderBuffer);

    SDL_GL_DeleteContext(context);

    SDL_DestroyWindow(window);

    ovrHmd_Destroy(hmd);

    ovr_Shutdown();

    SDL_Quit();

    return 0;
}