source: orxonox.OLD/orxonox/branches/bensch/lesson01.c @ 1775

/*
 * This code was created by Jeff Molofee '99 
 * (ported to Linux/GLX by Mihael Vrbanec '00)
 *
 * If you've found this code useful, please let me know.
 *
 * Visit Jeff at http://nehe.gamedev.net/
 * 
 * or for port-specific comments, questions, bugreports etc. 
 * email to Mihael.Vrbanec@stud.uni-karlsruhe.de
 */
 
#include <stdio.h>
#include <GL/glx.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <X11/extensions/xf86vmode.h>
#include <X11/keysym.h>

/* stuff about our window grouped together */
typedef struct {
    Display *dpy;
    int screen;
    Window win;
    GLXContext ctx;
    XSetWindowAttributes attr;
    Bool fs;
    Bool doubleBuffered;
    XF86VidModeModeInfo deskMode;
    int x, y;
    unsigned int width, height;
    unsigned int depth;    
} GLWindow;

/* attributes for a single buffered visual in RGBA format with at least
 * 4 bits per color and a 16 bit depth buffer */
static int attrListSgl[] = {GLX_RGBA, GLX_RED_SIZE, 4, 
    GLX_GREEN_SIZE, 4, 
    GLX_BLUE_SIZE, 4, 
    GLX_DEPTH_SIZE, 16,
    None};

/* attributes for a double buffered visual in RGBA format with at least
 * 4 bits per color and a 16 bit depth buffer */
static int attrListDbl[] = { GLX_RGBA, GLX_DOUBLEBUFFER, 
    GLX_RED_SIZE, 4, 
    GLX_GREEN_SIZE, 4, 
    GLX_BLUE_SIZE, 4, 
    GLX_DEPTH_SIZE, 16,
    None };

GLWindow GLWin;

/* function called when our window is resized (should only happen in window mode) */
void resizeGLScene(unsigned int width, unsigned int height)
{
    if (height == 0)    /* Prevent A Divide By Zero If The Window Is Too Small */
        height = 1;
    glViewport(0, 0, width, height);    /* Reset The Current Viewport And Perspective Transformation */
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45.0f, (GLfloat)width / (GLfloat)height, 0.1f, 100.0f);
    glMatrixMode(GL_MODELVIEW);
}

/* general OpenGL initialization function */
int initGL(GLvoid)
{
    glShadeModel(GL_SMOOTH);
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
    glClearDepth(1.0f);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LEQUAL);
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
    /* we use resizeGLScene once to set up our initial perspective */
    resizeGLScene(GLWin.width, GLWin.height);
    glFlush();
    return True;
}

/* Here goes our drawing code */
int drawGLScene(GLvoid)
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();
    if (GLWin.doubleBuffered)
    {
        glXSwapBuffers(GLWin.dpy, GLWin.win);
    }
    return True;    
}

/* function to release/destroy our resources and restoring the old desktop */
GLvoid killGLWindow(GLvoid)
{
    if (GLWin.ctx)
    {
        if (!glXMakeCurrent(GLWin.dpy, None, NULL))
        {
            printf("Could not release drawing context.\n");
        }
        glXDestroyContext(GLWin.dpy, GLWin.ctx);
        GLWin.ctx = NULL;
    }
    /* switch back to original desktop resolution if we were in fs */
    if (GLWin.fs)
    {
        XF86VidModeSwitchToMode(GLWin.dpy, GLWin.screen, &GLWin.deskMode);
        XF86VidModeSetViewPort(GLWin.dpy, GLWin.screen, 0, 0);
    }
    XCloseDisplay(GLWin.dpy);
}

/* this function creates our window and sets it up properly */
/* FIXME: bits is currently unused */
Bool createGLWindow(char* title, int width, int height, int bits,
                    Bool fullscreenflag)
{
    XVisualInfo *vi;
    Colormap cmap;
    int dpyWidth, dpyHeight;
    int i;
    int glxMajorVersion, glxMinorVersion;
    int vidModeMajorVersion, vidModeMinorVersion;
    XF86VidModeModeInfo **modes;
    int modeNum;
    int bestMode;
    Atom wmDelete;
    Window winDummy;
    unsigned int borderDummy;
    
    GLWin.fs = fullscreenflag;
    /* set best mode to current */
    bestMode = 0;
    /* get a connection */
    GLWin.dpy = XOpenDisplay(0);
    GLWin.screen = DefaultScreen(GLWin.dpy);
    XF86VidModeQueryVersion(GLWin.dpy, &vidModeMajorVersion,
        &vidModeMinorVersion);
    printf("XF86VidModeExtension-Version %d.%d\n", vidModeMajorVersion,
        vidModeMinorVersion);
    XF86VidModeGetAllModeLines(GLWin.dpy, GLWin.screen, &modeNum, &modes);
    /* save desktop-resolution before switching modes */
    GLWin.deskMode = *modes[0];
    /* look for mode with requested resolution */
    for (i = 0; i < modeNum; i++)
    {
        if ((modes[i]->hdisplay == width) && (modes[i]->vdisplay == height))
        {
            bestMode = i;
        }
    }
    /* get an appropriate visual */
    vi = glXChooseVisual(GLWin.dpy, GLWin.screen, attrListDbl);
    if (vi == NULL)
    {
        vi = glXChooseVisual(GLWin.dpy, GLWin.screen, attrListSgl);
        GLWin.doubleBuffered = False;
        printf("Only Singlebuffered Visual!\n");
    }
    else
    {
        GLWin.doubleBuffered = True;
        printf("Got Doublebuffered Visual!\n");
    }
    glXQueryVersion(GLWin.dpy, &glxMajorVersion, &glxMinorVersion);
    printf("glX-Version %d.%d\n", glxMajorVersion, glxMinorVersion);
    /* create a GLX context */
    GLWin.ctx = glXCreateContext(GLWin.dpy, vi, 0, GL_TRUE);
    /* create a color map */
    cmap = XCreateColormap(GLWin.dpy, RootWindow(GLWin.dpy, vi->screen),
        vi->visual, AllocNone);
    GLWin.attr.colormap = cmap;
    GLWin.attr.border_pixel = 0;

    if (GLWin.fs)
    {
        XF86VidModeSwitchToMode(GLWin.dpy, GLWin.screen, modes[bestMode]);
        XF86VidModeSetViewPort(GLWin.dpy, GLWin.screen, 0, 0);
        dpyWidth = modes[bestMode]->hdisplay;
        dpyHeight = modes[bestMode]->vdisplay;
        printf("Resolution %dx%d\n", dpyWidth, dpyHeight);
        XFree(modes);
    
        /* create a fullscreen window */
        GLWin.attr.override_redirect = True;
        GLWin.attr.event_mask = ExposureMask | KeyPressMask | ButtonPressMask |
            StructureNotifyMask;
        GLWin.win = XCreateWindow(GLWin.dpy, RootWindow(GLWin.dpy, vi->screen),
            0, 0, dpyWidth, dpyHeight, 0, vi->depth, InputOutput, vi->visual,
            CWBorderPixel | CWColormap | CWEventMask | CWOverrideRedirect,
            &GLWin.attr);
        XWarpPointer(GLWin.dpy, None, GLWin.win, 0, 0, 0, 0, 0, 0);
                XMapRaised(GLWin.dpy, GLWin.win);
        XGrabKeyboard(GLWin.dpy, GLWin.win, True, GrabModeAsync,
            GrabModeAsync, CurrentTime);
        XGrabPointer(GLWin.dpy, GLWin.win, True, ButtonPressMask,
            GrabModeAsync, GrabModeAsync, GLWin.win, None, CurrentTime);
    }
    else
    {
        /* create a window in window mode*/
        GLWin.attr.event_mask = ExposureMask | KeyPressMask | ButtonPressMask |
            StructureNotifyMask;
        GLWin.win = XCreateWindow(GLWin.dpy, RootWindow(GLWin.dpy, vi->screen),
            0, 0, width, height, 0, vi->depth, InputOutput, vi->visual,
            CWBorderPixel | CWColormap | CWEventMask, &GLWin.attr);
        /* only set window title and handle wm_delete_events if in windowed mode */
        wmDelete = XInternAtom(GLWin.dpy, "WM_DELETE_WINDOW", True);
        XSetWMProtocols(GLWin.dpy, GLWin.win, &wmDelete, 1);
        XSetStandardProperties(GLWin.dpy, GLWin.win, title,
            title, None, NULL, 0, NULL);
        XMapRaised(GLWin.dpy, GLWin.win);
    }       
    /* connect the glx-context to the window */
    glXMakeCurrent(GLWin.dpy, GLWin.win, GLWin.ctx);
    XGetGeometry(GLWin.dpy, GLWin.win, &winDummy, &GLWin.x, &GLWin.y,
        &GLWin.width, &GLWin.height, &borderDummy, &GLWin.depth);
    printf("Depth %d\n", GLWin.depth);
    if (glXIsDirect(GLWin.dpy, GLWin.ctx)) 
        printf("Congrats, you have Direct Rendering!\n");
    else
        printf("Sorry, no Direct Rendering possible!\n");
    initGL();
    return True;    
}

int main(int argc, char **argv)
{
    XEvent event;
    Bool done;
    
    done = False;
    /* default to fullscreen */
    GLWin.fs = True;
    createGLWindow("NeHe's OpenGL Framework", 640, 480, 24, GLWin.fs);

    /* wait for events*/ 
    while (!done)
    {
        /* handle the events in the queue */
        while (XPending(GLWin.dpy) > 0)
        {
            XNextEvent(GLWin.dpy, &event);
            switch (event.type)
            {
                case Expose:
                        if (event.xexpose.count != 0)
                            break;
                    drawGLScene();
                        break;
            case ConfigureNotify:
            /* call resizeGLScene only if our window-size changed */
                if ((event.xconfigure.width != GLWin.width) || 
                    (event.xconfigure.height != GLWin.height))
                {
                    GLWin.width = event.xconfigure.width;
                    GLWin.height = event.xconfigure.height;
                        printf("Resize event\n");
                    resizeGLScene(event.xconfigure.width,
                        event.xconfigure.height);
                }
                break;
            /* exit in case of a mouse button press */
            case ButtonPress:     
                done = True;
                break;
            case KeyPress:
                if (XLookupKeysym(&event.xkey, 0) == XK_Escape)
                {
                    done = True;
                }
                if (XLookupKeysym(&event.xkey,0) == XK_F1)
                {
                    killGLWindow();
                    GLWin.fs = !GLWin.fs;
                    createGLWindow("NeHe's OpenGL Framework", 640, 480, 24, GLWin.fs);
                }
                break;
            case ClientMessage:    
                if (*XGetAtomName(GLWin.dpy, event.xclient.message_type) == 
                    *"WM_PROTOCOLS")
                {
                    printf("Exiting sanely...\n");
                    done = True;
                }
                break;
            default:
                break;
            }
        }
        drawGLScene();
    }
    killGLWindow();
    exit (0);
}