Tutorial00_HelloLinux.cpp

/*     Copyright 2015-2018 Egor Yusov
 *  
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF ANY PROPRIETARY RIGHTS.
 *
 *  In no event and under no legal theory, whether in tort (including negligence), 
 *  contract, or otherwise, unless required by applicable law (such as deliberate 
 *  and grossly negligent acts) or agreed to in writing, shall any Contributor be
 *  liable for any damages, including any direct, indirect, special, incidental, 
 *  or consequential damages of any character arising as a result of this License or 
 *  out of the use or inability to use the software (including but not limited to damages 
 *  for loss of goodwill, work stoppage, computer failure or malfunction, or any and 
 *  all other commercial damages or losses), even if such Contributor has been advised 
 *  of the possibility of such damages.
 */

#include <memory>
#include <iostream>

#include <GL/glx.h>
#include <GL/gl.h>

#if VULKAN_SUPPORTED

#    include <xcb/xcb.h>

// https://code.woboq.org/qt5/include/xcb/xcb_icccm.h.html
enum XCB_SIZE_HINT
{
    XCB_SIZE_HINT_US_POSITION   = 1 << 0,
    XCB_SIZE_HINT_US_SIZE       = 1 << 1,
    XCB_SIZE_HINT_P_POSITION    = 1 << 2,
    XCB_SIZE_HINT_P_SIZE        = 1 << 3,
    XCB_SIZE_HINT_P_MIN_SIZE    = 1 << 4,
    XCB_SIZE_HINT_P_MAX_SIZE    = 1 << 5,
    XCB_SIZE_HINT_P_RESIZE_INC  = 1 << 6,
    XCB_SIZE_HINT_P_ASPECT      = 1 << 7,
    XCB_SIZE_HINT_BASE_SIZE     = 1 << 8,
    XCB_SIZE_HINT_P_WIN_GRAVITY = 1 << 9
};

struct xcb_size_hints_t
{
    uint32_t flags;                          /** User specified flags */
    int32_t  x, y;                           /** User-specified position */
    int32_t  width, height;                  /** User-specified size */
    int32_t  min_width, min_height;          /** Program-specified minimum size */
    int32_t  max_width, max_height;          /** Program-specified maximum size */
    int32_t  width_inc, height_inc;          /** Program-specified resize increments */
    int32_t  min_aspect_num, min_aspect_den; /** Program-specified minimum aspect ratios */
    int32_t  max_aspect_num, max_aspect_den; /** Program-specified maximum aspect ratios */
    int32_t  base_width, base_height;        /** Program-specified base size */
    uint32_t win_gravity;                    /** Program-specified window gravity */
};

#endif

// Undef symbols defined by XLib
#ifdef Bool
#    undef Bool
#endif
#ifdef True
#    undef True
#endif
#ifdef False
#    undef False
#endif


#ifndef PLATFORM_LINUX
#    define PLATFORM_LINUX 1
#endif

#if GL_SUPPORTED
#    include "Graphics/GraphicsEngineOpenGL/interface/EngineFactoryOpenGL.h"
#endif

#if VULKAN_SUPPORTED
#    include "Graphics/GraphicsEngineVulkan/interface/EngineFactoryVk.h"
#endif

#include "Graphics/GraphicsEngine/interface/RenderDevice.h"
#include "Graphics/GraphicsEngine/interface/DeviceContext.h"
#include "Graphics/GraphicsEngine/interface/SwapChain.h"

#include "Common/interface/RefCntAutoPtr.hpp"


using namespace Diligent;

#ifndef GLX_CONTEXT_MAJOR_VERSION_ARB
#    define GLX_CONTEXT_MAJOR_VERSION_ARB 0x2091
#endif

#ifndef GLX_CONTEXT_MINOR_VERSION_ARB
#    define GLX_CONTEXT_MINOR_VERSION_ARB 0x2092
#endif

#ifndef GLX_CONTEXT_FLAGS_ARB
#    define GLX_CONTEXT_FLAGS_ARB 0x2094
#endif

#ifndef GLX_CONTEXT_DEBUG_BIT_ARB
#    define GLX_CONTEXT_DEBUG_BIT_ARB 0x0001
#endif

typedef GLXContext (*glXCreateContextAttribsARBProc)(Display*, GLXFBConfig, GLXContext, int, const int*);

#if VULKAN_SUPPORTED
struct XCBInfo
{
    xcb_connection_t*        connection            = nullptr;
    uint32_t                 window                = 0;
    uint16_t                 width                 = 0;
    uint16_t                 height                = 0;
    xcb_intern_atom_reply_t* atom_wm_delete_window = nullptr;
};
#endif

// For this tutorial, we will use simple vertex shader
// that creates a procedural triangle

// Diligent Engine can use HLSL source for all supported platforms
// It will convert HLSL to GLSL for OpenGL/Vulkan

static const char* VSSource = R"(
struct PSInput 
{
    float4 Pos   : SV_POSITION; 
    float3 Color : COLOR; 
};

void main(in  uint    VertId : SV_VertexID,
          out PSInput PSIn) 
{
    float4 Pos[3];
    Pos[0] = float4(-0.5, -0.5, 0.0, 1.0);
    Pos[1] = float4( 0.0, +0.5, 0.0, 1.0);
    Pos[2] = float4(+0.5, -0.5, 0.0, 1.0);

    float3 Col[3];
    Col[0] = float3(1.0, 0.0, 0.0); // red
    Col[1] = float3(0.0, 1.0, 0.0); // green
    Col[2] = float3(0.0, 0.0, 1.0); // blue

    PSIn.Pos   = Pos[VertId];
    PSIn.Color = Col[VertId];
}
)";

// Pixel shader will simply output interpolated vertex color
static const char* PSSource = R"(
struct PSInput 
{ 
    float4 Pos   : SV_POSITION; 
    float3 Color : COLOR; 
};

struct PSOutput
{ 
    float4 Color : SV_TARGET; 
};

void main(in  PSInput  PSIn,
          out PSOutput PSOut)
{
    PSOut.Color = float4(PSIn.Color.rgb, 1.0);
}
)";


class Tutorial00App
{
public:
    Tutorial00App()
    {
    }

    ~Tutorial00App()
    {
        m_pImmediateContext->Flush();
    }

#if GL_SUPPORTED
    bool OnGLContextCreated(Display* display, Window NativeWindowHandle)
    {
        SwapChainDesc SCDesc;
        // Declare function pointer
        auto* pFactoryOpenGL = GetEngineFactoryOpenGL();

        EngineGLCreateInfo EngineCI;
        EngineCI.Window.WindowId = NativeWindowHandle;
        EngineCI.Window.pDisplay = display;

        pFactoryOpenGL->CreateDeviceAndSwapChainGL(EngineCI, &m_pDevice, &m_pImmediateContext, SCDesc, &m_pSwapChain);

        return true;
    }
#endif

#if VULKAN_SUPPORTED
    bool InitVulkan(XCBInfo& xcbInfo)
    {
        EngineVkCreateInfo EngineCI;

        auto* pFactoryVk = GetEngineFactoryVk();
        pFactoryVk->CreateDeviceAndContextsVk(EngineCI, &m_pDevice, &m_pImmediateContext);
        SwapChainDesc     SCDesc;
        LinuxNativeWindow XCBWindow;
        XCBWindow.WindowId       = xcbInfo.window;
        XCBWindow.pXCBConnection = xcbInfo.connection;
        pFactoryVk->CreateSwapChainVk(m_pDevice, m_pImmediateContext, SCDesc, XCBWindow, &m_pSwapChain);

        return true;
    }
#endif

    void CreateResources()
    {
        // Pipeline state object encompasses configuration of all GPU stages

        GraphicsPipelineStateCreateInfo PSOCreateInfo;
        PipelineStateDesc&              PSODesc = PSOCreateInfo.PSODesc;

        // Pipeline state name is used by the engine to report issues
        // It is always a good idea to give objects descriptive names
        PSODesc.Name = "Simple triangle PSO";

        // This is a graphics pipeline
        PSODesc.PipelineType = PIPELINE_TYPE_GRAPHICS;

        // This tutorial will render to a single render target
        PSOCreateInfo.GraphicsPipeline.NumRenderTargets = 1;
        // Set render target format which is the format of the swap chain's color buffer
        PSOCreateInfo.GraphicsPipeline.RTVFormats[0] = m_pSwapChain->GetDesc().ColorBufferFormat;
        // This tutorial will not use depth buffer
        PSOCreateInfo.GraphicsPipeline.DSVFormat = TEX_FORMAT_D32_FLOAT;
        // Primitive topology defines what kind of primitives will be rendered by this pipeline state
        PSOCreateInfo.GraphicsPipeline.PrimitiveTopology = PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;
        // No back face culling for this tutorial
        PSOCreateInfo.GraphicsPipeline.RasterizerDesc.CullMode = CULL_MODE_NONE;
        // Disable depth testing
        PSOCreateInfo.GraphicsPipeline.DepthStencilDesc.DepthEnable = False;

        ShaderCreateInfo ShaderCI;
        // Tell the system that the shader source code is in HLSL.
        // For OpenGL, the engine will convert this into GLSL behind the scene
        ShaderCI.SourceLanguage = SHADER_SOURCE_LANGUAGE_HLSL;
        // OpenGL backend requires emulated combined HLSL texture samplers (g_Texture + g_Texture_sampler combination)
        ShaderCI.Desc.UseCombinedTextureSamplers = true;
        // Create vertex shader
        RefCntAutoPtr<IShader> pVS;
        {
            ShaderCI.Desc.ShaderType = SHADER_TYPE_VERTEX;
            ShaderCI.EntryPoint      = "main";
            ShaderCI.Desc.Name       = "Triangle vertex shader";
            ShaderCI.Source          = VSSource;
            m_pDevice->CreateShader(ShaderCI, &pVS);
        }

        // Create pixel shader
        RefCntAutoPtr<IShader> pPS;
        {
            ShaderCI.Desc.ShaderType = SHADER_TYPE_PIXEL;
            ShaderCI.EntryPoint      = "main";
            ShaderCI.Desc.Name       = "Triangle pixel shader";
            ShaderCI.Source          = PSSource;
            m_pDevice->CreateShader(ShaderCI, &pPS);
        }

        // Finally, create the pipeline state
        PSOCreateInfo.pVS = pVS;
        PSOCreateInfo.pPS = pPS;
        m_pDevice->CreateGraphicsPipelineState(PSOCreateInfo, &m_pPSO);
    }

    void Render()
    {
        // Set render targets before issuing any draw command.
        // Note that Present() unbinds the back buffer if it is set as render target.
        auto* pRTV = m_pSwapChain->GetCurrentBackBufferRTV();
        auto* pDSV = m_pSwapChain->GetDepthBufferDSV();
        m_pImmediateContext->SetRenderTargets(1, &pRTV, pDSV, RESOURCE_STATE_TRANSITION_MODE_TRANSITION);

        // Clear the back buffer
        const float ClearColor[] = {0.350f, 0.350f, 0.350f, 1.0f};
        // Let the engine perform required state transitions
        m_pImmediateContext->ClearRenderTarget(pRTV, ClearColor, RESOURCE_STATE_TRANSITION_MODE_TRANSITION);
        m_pImmediateContext->ClearDepthStencil(pDSV, CLEAR_DEPTH_FLAG, 1.f, 0, RESOURCE_STATE_TRANSITION_MODE_TRANSITION);

        // Set pipeline state in the immediate context
        m_pImmediateContext->SetPipelineState(m_pPSO);

        // Typically we should now call CommitShaderResources(), however shaders in this example don't
        // use any resources.

        DrawAttribs drawAttrs;
        drawAttrs.NumVertices = 3; // We will render 3 vertices
        m_pImmediateContext->Draw(drawAttrs);
    }

    void Present()
    {
        m_pSwapChain->Present();
    }

    void WindowResize(Uint32 Width, Uint32 Height)
    {
        if (m_pSwapChain)
            m_pSwapChain->Resize(Width, Height);
    }

    RENDER_DEVICE_TYPE GetDeviceType() const { return m_DeviceType; }

private:
    RefCntAutoPtr<IRenderDevice>  m_pDevice;
    RefCntAutoPtr<IDeviceContext> m_pImmediateContext;
    RefCntAutoPtr<ISwapChain>     m_pSwapChain;
    RefCntAutoPtr<IPipelineState> m_pPSO;
    RENDER_DEVICE_TYPE            m_DeviceType = RENDER_DEVICE_TYPE_GL;
};

using namespace Diligent;


#if VULKAN_SUPPORTED

XCBInfo InitXCBConnectionAndWindow()
{
    XCBInfo info;

    int scr         = 0;
    info.connection = xcb_connect(nullptr, &scr);
    if (info.connection == nullptr || xcb_connection_has_error(info.connection))
    {
        std::cerr << "Unable to make an XCB connection\n";
        exit(-1);
    }

    const xcb_setup_t*    setup = xcb_get_setup(info.connection);
    xcb_screen_iterator_t iter  = xcb_setup_roots_iterator(setup);
    while (scr-- > 0)
        xcb_screen_next(&iter);

    auto screen = iter.data;

    info.width  = 1024;
    info.height = 768;

    uint32_t value_mask, value_list[32];

    info.window = xcb_generate_id(info.connection);

    value_mask    = XCB_CW_BACK_PIXEL | XCB_CW_EVENT_MASK;
    value_list[0] = screen->black_pixel;
    value_list[1] = XCB_EVENT_MASK_KEY_RELEASE | XCB_EVENT_MASK_EXPOSURE | XCB_EVENT_MASK_STRUCTURE_NOTIFY;

    xcb_create_window(info.connection, XCB_COPY_FROM_PARENT, info.window, screen->root, 0, 0, info.width, info.height, 0,
                      XCB_WINDOW_CLASS_INPUT_OUTPUT, screen->root_visual, value_mask, value_list);

    // Magic code that will send notification when window is destroyed
    xcb_intern_atom_cookie_t cookie = xcb_intern_atom(info.connection, 1, 12, "WM_PROTOCOLS");
    xcb_intern_atom_reply_t* reply  = xcb_intern_atom_reply(info.connection, cookie, 0);

    xcb_intern_atom_cookie_t cookie2 = xcb_intern_atom(info.connection, 0, 16, "WM_DELETE_WINDOW");
    info.atom_wm_delete_window       = xcb_intern_atom_reply(info.connection, cookie2, 0);

    xcb_change_property(info.connection, XCB_PROP_MODE_REPLACE, info.window, (*reply).atom, 4, 32, 1,
                        &(*info.atom_wm_delete_window).atom);
    free(reply);

    const char* title = "Tutorial00: Hello Linux (Vulkan)";
    xcb_change_property(info.connection, XCB_PROP_MODE_REPLACE, info.window, XCB_ATOM_WM_NAME, XCB_ATOM_STRING,
                        8, strlen(title), title);

    // https://stackoverflow.com/a/27771295
    xcb_size_hints_t hints = {};
    hints.flags            = XCB_SIZE_HINT_P_MIN_SIZE;
    hints.min_width        = 320;
    hints.min_height       = 240;
    xcb_change_property(info.connection, XCB_PROP_MODE_REPLACE, info.window, XCB_ATOM_WM_NORMAL_HINTS, XCB_ATOM_WM_SIZE_HINTS,
                        32, sizeof(xcb_size_hints_t), &hints);

    xcb_map_window(info.connection, info.window);

    // Force the x/y coordinates to 100,100 results are identical in consecutive
    // runs
    const uint32_t coords[] = {100, 100};
    xcb_configure_window(info.connection, info.window, XCB_CONFIG_WINDOW_X | XCB_CONFIG_WINDOW_Y, coords);
    xcb_flush(info.connection);

    xcb_generic_event_t* e;
    while ((e = xcb_wait_for_event(info.connection)))
    {
        if ((e->response_type & ~0x80) == XCB_EXPOSE) break;
    }
    return info;
}

void DestroyXCBConnectionAndWindow(XCBInfo& info)
{
    xcb_destroy_window(info.connection, info.window);
    xcb_disconnect(info.connection);
}

int xcb_main()
{
    std::unique_ptr<Tutorial00App> TheApp(new Tutorial00App);

    auto xcbInfo = InitXCBConnectionAndWindow();
    TheApp->InitVulkan(xcbInfo);
    TheApp->CreateResources();
    xcb_flush(xcbInfo.connection);
    while (true)
    {
        xcb_generic_event_t* event;

        bool Quit = false;
        while ((event = xcb_poll_for_event(xcbInfo.connection)) != nullptr)
        {
            switch (event->response_type & 0x7f)
            {
                case XCB_CLIENT_MESSAGE:
                    if ((*(xcb_client_message_event_t*)event).data.data32[0] ==
                        (*xcbInfo.atom_wm_delete_window).atom)
                    {
                        Quit = true;
                    }
                    break;

                case XCB_KEY_RELEASE:
                {
                    const auto* keyEvent = reinterpret_cast<const xcb_key_release_event_t*>(event);
                    switch (keyEvent->detail)
                    {
#    define KEY_ESCAPE 0x9
                        case KEY_ESCAPE:
                            Quit = true;
                            break;
                    }
                }
                break;

                case XCB_DESTROY_NOTIFY:
                    Quit = true;
                    break;

                case XCB_CONFIGURE_NOTIFY:
                {
                    const auto* cfgEvent = reinterpret_cast<const xcb_configure_notify_event_t*>(event);
                    if ((cfgEvent->width != xcbInfo.width) || (cfgEvent->height != xcbInfo.height))
                    {
                        xcbInfo.width  = cfgEvent->width;
                        xcbInfo.height = cfgEvent->height;
                        if ((xcbInfo.width > 0) && (xcbInfo.height > 0))
                        {
                            TheApp->WindowResize(xcbInfo.width, xcbInfo.height);
                        }
                    }
                }
                break;

                default:
                    break;
            }
            free(event);
        }

        if (Quit)
            break;

        TheApp->Render();
        TheApp->Present();
    }
    TheApp.reset();
    DestroyXCBConnectionAndWindow(xcbInfo);
    return 0;
}

#endif

#if GL_SUPPORTED
int x_main()
{
    std::unique_ptr<Tutorial00App> TheApp(new Tutorial00App);

    Display* display = XOpenDisplay(0);

    // clang-format off
    static int visual_attribs[] =
    {
        GLX_RENDER_TYPE,    GLX_RGBA_BIT,
        GLX_DRAWABLE_TYPE,  GLX_WINDOW_BIT,
        GLX_DOUBLEBUFFER,   true,

        // The largest available total RGBA color buffer size (sum of GLX_RED_SIZE, 
        // GLX_GREEN_SIZE, GLX_BLUE_SIZE, and GLX_ALPHA_SIZE) of at least the minimum
        // size specified for each color component is preferred.
        GLX_RED_SIZE,       8,
        GLX_GREEN_SIZE,     8,
        GLX_BLUE_SIZE,      8,
        GLX_ALPHA_SIZE,     8,

        // The largest available depth buffer of at least GLX_DEPTH_SIZE size is preferred
        GLX_DEPTH_SIZE,     24,

        //GLX_SAMPLE_BUFFERS, 1,
        GLX_SAMPLES, 1,
        None
     };
    // clang-format on

    int          fbcount = 0;
    GLXFBConfig* fbc     = glXChooseFBConfig(display, DefaultScreen(display), visual_attribs, &fbcount);
    if (!fbc)
    {
        std::cerr << "Failed to retrieve a framebuffer config\n";
        return -1;
    }

    XVisualInfo* vi = glXGetVisualFromFBConfig(display, fbc[0]);

    XSetWindowAttributes swa;
    swa.colormap     = XCreateColormap(display, RootWindow(display, vi->screen), vi->visual, AllocNone);
    swa.border_pixel = 0;
    swa.event_mask =
        StructureNotifyMask |
        ExposureMask |
        KeyPressMask |
        KeyReleaseMask |
        ButtonPressMask |
        ButtonReleaseMask |
        PointerMotionMask;

    Window win = XCreateWindow(display, RootWindow(display, vi->screen), 0, 0, 1024, 768, 0, vi->depth, InputOutput, vi->visual, CWBorderPixel | CWColormap | CWEventMask, &swa);
    if (!win)
    {
        std::cerr << "Failed to create window.\n";
        return -1;
    }

    {
        auto SizeHints        = XAllocSizeHints();
        SizeHints->flags      = PMinSize;
        SizeHints->min_width  = 320;
        SizeHints->min_height = 240;
        XSetWMNormalHints(display, win, SizeHints);
        XFree(SizeHints);
    }

    XMapWindow(display, win);

    glXCreateContextAttribsARBProc glXCreateContextAttribsARB = nullptr;
    {
        // Create an oldstyle context first, to get the correct function pointer for glXCreateContextAttribsARB
        GLXContext ctx_old         = glXCreateContext(display, vi, 0, GL_TRUE);
        glXCreateContextAttribsARB = (glXCreateContextAttribsARBProc)glXGetProcAddress((const GLubyte*)"glXCreateContextAttribsARB");
        glXMakeCurrent(display, None, NULL);
        glXDestroyContext(display, ctx_old);
    }

    if (glXCreateContextAttribsARB == nullptr)
    {
        std::cerr << "glXCreateContextAttribsARB entry point not found. Aborting.\n";
        return -1;
    }

    int Flags = GLX_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB;
#    ifdef _DEBUG
    Flags |= GLX_CONTEXT_DEBUG_BIT_ARB;
#    endif

    int major_version = 4;
    int minor_version = 3;
    // clang-format off
    static int context_attribs[] =
    {
        GLX_CONTEXT_MAJOR_VERSION_ARB, major_version,
        GLX_CONTEXT_MINOR_VERSION_ARB, minor_version,
        GLX_CONTEXT_FLAGS_ARB, Flags,
        None
    };
    // clang-format on

    constexpr int True = 1;
    GLXContext    ctx  = glXCreateContextAttribsARB(display, fbc[0], NULL, True, context_attribs);
    if (!ctx)
    {
        std::cerr << "Failed to create GL context.\n";
        return -1;
    }
    XFree(fbc);


    glXMakeCurrent(display, win, ctx);
    TheApp->OnGLContextCreated(display, win);
    TheApp->CreateResources();
    XStoreName(display, win, "Tutorial00: Hello Linux (OpenGL)");
    while (true)
    {
        bool   EscPressed = false;
        XEvent xev;
        // Handle all events in the queue
        while (XCheckMaskEvent(display, 0xFFFFFFFF, &xev))
        {
            switch (xev.type)
            {
                case KeyPress:
                {
                    KeySym keysym;
                    char   buffer[80];
                    int    num_char = XLookupString((XKeyEvent*)&xev, buffer, _countof(buffer), &keysym, 0);
                    (void)num_char;
                    EscPressed = (keysym == XK_Escape);
                }

                case ConfigureNotify:
                {
                    XConfigureEvent& xce = reinterpret_cast<XConfigureEvent&>(xev);
                    if (xce.width != 0 && xce.height != 0)
                        TheApp->WindowResize(xce.width, xce.height);
                    break;
                }
            }
        }

        if (EscPressed)
            break;

        TheApp->Render();

        TheApp->Present();
    }

    TheApp.reset();

    ctx = glXGetCurrentContext();
    glXMakeCurrent(display, None, NULL);
    glXDestroyContext(display, ctx);
    XDestroyWindow(display, win);
    XCloseDisplay(display);

    return 0;
}
#endif

int main(int argc, char** argv)
{
    RENDER_DEVICE_TYPE DevType = RENDER_DEVICE_TYPE_UNDEFINED;

#if VULKAN_SUPPORTED
    DevType = RENDER_DEVICE_TYPE_VULKAN;
#elif GL_SUPPORTED
    DevType = RENDER_DEVICE_TYPE_GL;
#else
#    error No supported backends
#endif

    int arg = 0;
    while (arg < argc && strcmp(argv[arg], "--mode") != 0 && strcmp(argv[arg], "-m") != 0)
        ++arg;
    if (arg + 1 < argc)
    {
        const auto* mode = argv[arg + 1];
        if (strcasecmp(mode, "GL") == 0)
        {
#if GL_SUPPORTED
            DevType = RENDER_DEVICE_TYPE_GL;
#else
            std::cerr << "OpenGL is not supported";
            return -1;
#endif
        }
        else if (strcasecmp(mode, "VK") == 0)
        {
#if VULKAN_SUPPORTED
            DevType = RENDER_DEVICE_TYPE_VULKAN;
#else
            std::cerr << "Vulkan is not supported";
            return -1;
#endif
        }
        else
        {
            std::cerr << mode << " is not a valid device type. Only the following types are supported: GL, VK";
            return -1;
        }
    }

#if VULKAN_SUPPORTED
    if (DevType == RENDER_DEVICE_TYPE_VULKAN)
    {
        return xcb_main();
    }
#endif

#if GL_SUPPORTED
    if (DevType == RENDER_DEVICE_TYPE_GL)
    {
        return x_main();
    }
#endif

    return -1;
}