progs/xdemos/glxdemo.c

   1
   2
   3 /*
   4  * A demonstration of using the GLX functions.  This program is in the
   5  * public domain.
   6  *
   7  * Brian Paul
   8  */
   9
  10 #include <GL/gl.h>
  11 #include <GL/glx.h>
  12 #include <stdio.h>
  13 #include <stdlib.h>
  14
  15
  16
  17 static void redraw( Display *dpy, Window w )
  18 {
  19    printf("Redraw event\n");
  20
  21    glClear( GL_COLOR_BUFFER_BIT );
  22
  23    glColor3f( 1.0, 1.0, 0.0 );
  24    glRectf( -0.8, -0.8, 0.8, 0.8 );
  25
  26    glXSwapBuffers( dpy, w );
  27 }
  28
  29
  30
  31 static void resize( unsigned int width, unsigned int height )
  32 {
  33    printf("Resize event\n");
  34    glViewport( 0, 0, width, height );
  35    glMatrixMode( GL_PROJECTION );
  36    glLoadIdentity();
  37    glOrtho( -1.0, 1.0, -1.0, 1.0, -1.0, 1.0 );
  38 }
  39
  40
  41
  42 static Window make_rgb_db_window( Display *dpy,
  43                                   unsigned int width, unsigned int height )
  44 {
  45    int attrib[] = { GLX_RGBA,
  46                     GLX_RED_SIZE, 1,
  47                     GLX_GREEN_SIZE, 1,
  48                     GLX_BLUE_SIZE, 1,
  49                     GLX_DOUBLEBUFFER,
  50                     None };
  51    int scrnum;
  52    XSetWindowAttributes attr;
  53    unsigned long mask;
  54    Window root;
  55    Window win;
  56    GLXContext ctx;
  57    XVisualInfo *visinfo;
  58
  59    scrnum = DefaultScreen( dpy );
  60    root = RootWindow( dpy, scrnum );
  61
  62    visinfo = glXChooseVisual( dpy, scrnum, attrib );
  63    if (!visinfo) {
  64       printf("Error: couldn't get an RGB, Double-buffered visual\n");
  65       exit(1);
  66    }
  67
  68    /* window attributes */
  69    attr.background_pixel = 0;
  70    attr.border_pixel = 0;
  71    attr.colormap = XCreateColormap( dpy, root, visinfo->visual, AllocNone);
  72    attr.event_mask = StructureNotifyMask | ExposureMask;
  73    mask = CWBackPixel | CWBorderPixel | CWColormap | CWEventMask;
  74
  75    win = XCreateWindow( dpy, root, 0, 0, width, height,
  76                         0, visinfo->depth, InputOutput,
  77                         visinfo->visual, mask, &attr );
  78
  79    ctx = glXCreateContext( dpy, visinfo, NULL, True );
  80    if (!ctx) {
  81       printf("Error: glXCreateContext failed\n");
  82       exit(1);
  83    }
  84
  85    glXMakeCurrent( dpy, win, ctx );
  86
  87    return win;
  88 }
  89
  90
  91 static void event_loop( Display *dpy )
  92 {
  93    XEvent event;
  94
  95    while (1) {
  96       XNextEvent( dpy, &event );
  97
  98       switch (event.type) {
  99          case Expose:
 100             redraw( dpy, event.xany.window );
 101             break;
 102          case ConfigureNotify:
 103             resize( event.xconfigure.width, event.xconfigure.height );
 104             break;
 105       }
 106    }
 107 }
 108
 109
 110
 111 int main( int argc, char *argv[] )
 112 {
 113    Display *dpy;
 114    Window win;
 115
 116    dpy = XOpenDisplay(NULL);
 117
 118    win = make_rgb_db_window( dpy, 300, 300 );
 119
 120    glShadeModel( GL_FLAT );
 121    glClearColor( 0.5, 0.5, 0.5, 1.0 );
 122
 123    XMapWindow( dpy, win );
 124
 125    event_loop( dpy );
 126    return 0;
 127 }