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#include "OpenGLContext.h"

#include <GL/gl.h>

#include <GL/glx.h>

#include <X11/Xlib.h>

#include <stdio.h>

#include <string.h>

#include <unistd.h>

// vmode extension for mode settings, gamma control, etc.

#include <X11/extensions/xf86vmode.h>

struct OpenGLContext::OpenGLContextInfo{

    Display *display;

    Window window;

    GLXContext context;

    OpenGLContextInfo() : display(NULL), window(0), context(NULL){}

};

std::vector<ScreenInfo> OpenGLContext::GetScreenInfo(){

    std::vector<ScreenInfo> ret;

    // Connection to default X Server

    Display *display = XOpenDisplay(NULL);

    unsigned int nScreens = ScreenCount(display);

    for(unsigned int i=0; i<nScreens; i++){

        Screen *XScreen = ScreenOfDisplay(display, i);

        ScreenInfo screen;

        screen.resX = XScreen->width;

        screen.resY = XScreen->height;

        char buff[100];

        sprintf(buff, "XScreen no. %d", i);

        screen.name = buff;

        ret.push_back(screen);

    }

    XCloseDisplay(display);

    return ret;

}

OpenGLContext::OpenGLContext(uint _screenNum) : screenNum(_screenNum){

    contextInfo = new OpenGLContextInfo();

    contextInfo->display = XOpenDisplay(NULL);

    if((int)screenNum+1 > ScreenCount(contextInfo->display))

        throw "Could not create OpenGLContext. Screen not available!";

    Screen *xScreen = ScreenOfDisplay(contextInfo->display, screenNum);

    screenResX = xScreen->width;

    screenResY = xScreen->height;

    // Create a OpenGL OpenGLContext on the specified X screen

    contextInfo->window = RootWindow(contextInfo->display, screenNum);

    int attrListDbl[] = {

        GLX_RGBA, GLX_DOUBLEBUFFER,

        GLX_RED_SIZE, 4,

        GLX_GREEN_SIZE, 4,

        GLX_BLUE_SIZE, 4,

        None

    };

    XVisualInfo *visualInfo = glXChooseVisual(contextInfo->display, screenNum, attrListDbl);

    int glxMajor, glxMinor = 0;

    glXQueryVersion(contextInfo->display, &glxMajor, &glxMinor);

    std::cout << "GLX-Version " << glxMajor << "." << glxMinor << std::endl;

    // Create a GLX OpenGLContext

    bool directRendering = True;

    contextInfo->context = glXCreateContext(contextInfo->display, visualInfo,  NULL, directRendering);

    // Create colormap

    Colormap colormap = XCreateColormap(contextInfo->display,contextInfo->window,visualInfo->visual,AllocNone);

    // Create the actual window

    unsigned long wamask = CWColormap;

    XSetWindowAttributes wa;

    wa.colormap = colormap;

    wa.border_pixel = 0;

    wa.event_mask = 0;

    // bypass window manager

    wa.override_redirect = False;

    // show no cursor

    wa.cursor = 0;

    contextInfo->window = XCreateWindow(contextInfo->display, contextInfo->window, 0, 0, screenResX, screenResY, 0, visualInfo->depth, InputOutput, visualInfo->visual, wamask, &wa);

    if(!contextInfo->window)

        std::cerr << "Failed to create X window!" << std::endl;

    // Raise window (necessary)

    XMapRaised(contextInfo->display, contextInfo->window);

    // Connect the glx-OpenGLContext to the window

    glXMakeCurrent(contextInfo->display, contextInfo->window, contextInfo->context);

    //XSaveOpenGLContext

    XFlush(contextInfo->display);

    // Check if OpenGLContext is direct

    if (glXIsDirect(contextInfo->display, contextInfo->context))

        std::cout << "OpenGLContext is direct\n";

    else

        std::cout << "OpenGLContext is not direct\n";

    // Set swap interval to 1 for standard vsync

    typedef GLvoid (*glXSwapIntervalSGIFunc) (GLint);

    const char *glx_extensions = glXQueryExtensionsString(contextInfo->display, screenNum);

    if (strstr(glx_extensions, "GLX_SGI_swap_control")) {

        PFNGLXSWAPINTERVALSGIPROC SwapIntervalSGI = (PFNGLXSWAPINTERVALSGIPROC)glXGetProcAddressARB((const GLubyte*)"glXSwapIntervalSGI");

        SwapIntervalSGI(1);

    } else if (strstr(glx_extensions, "GLX_EXT_swap_control")) {

        PFNGLXSWAPINTERVALEXTPROC SwapIntervalEXT = (PFNGLXSWAPINTERVALEXTPROC)glXGetProcAddressARB((const GLubyte*)"glXSwapIntervalEXT");

        SwapIntervalEXT(contextInfo->display, contextInfo->window, 1);

    } else {

        std::cerr << "OpenGLContext.Unix Error: Could not access swap interval extension!" << std::endl;

    }

    // Adjust gamma to one

    setGamma(1.0);

}

void OpenGLContext::setGamma(float gamma){

    // Adjust gamma

    XF86VidModeGamma xf86Gamma = {gamma, gamma, gamma};

    XF86VidModeSetGamma(contextInfo->display, screenNum, &xf86Gamma);

}

void OpenGLContext::makeContextCurrent(){

    glXMakeCurrent(contextInfo->display, contextInfo->window, contextInfo->context);

}

void OpenGLContext::flush(){

    // Swap buffers

    glXSwapBuffers(contextInfo->display, contextInfo->window);

    // Synchronize CPU with vsync buffer swap

    //glFinish();

    //glXWaitGL();

}

OpenGLContext::~OpenGLContext(){

    std::cout<<"Releasing OpenGL Context\n"<<std::flush;

    if(contextInfo->context){

        // Release context (None, NULL)

        if(!glXMakeCurrent(contextInfo->display, None, NULL))

            std::cerr << "Error. Could not release drawing OpenGLContext." << std::endl;

        glXDestroyContext(contextInfo->display, contextInfo->context);

        XCloseDisplay(contextInfo->display);

        delete contextInfo;

    }

}