progs/xdemos/glxpixmap.c

   1 /* $Id: glxpixmap.c,v 1.1 1999/08/19 00:55:43 jtg Exp $ */
   2
   3
   4 /*
   5  * A demonstration of using the GLXPixmap functions.  This program is in
   6  * the public domain.
   7  *
   8  * Brian Paul
   9  */
  10
  11
  12 /*
  13  * $Id: glxpixmap.c,v 1.1 1999/08/19 00:55:43 jtg Exp $
  14  */
  15
  16
  17 #include <GL/gl.h>
  18 #include <GL/glx.h>
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21
  22
  23
  24 static GLXContext ctx;
  25 static XVisualInfo *visinfo;
  26 static GC gc;
  27
  28
  29
  30 static Window make_rgb_window( Display *dpy,
  31                                   unsigned int width, unsigned int height )
  32 {
  33    int attrib[] = { GLX_RGBA,
  34                     GLX_RED_SIZE, 1,
  35                     GLX_GREEN_SIZE, 1,
  36                     GLX_BLUE_SIZE, 1,
  37                     None };
  38    int scrnum;
  39    XSetWindowAttributes attr;
  40    unsigned long mask;
  41    Window root;
  42    Window win;
  43
  44    scrnum = DefaultScreen( dpy );
  45    root = RootWindow( dpy, scrnum );
  46
  47    visinfo = glXChooseVisual( dpy, scrnum, attrib );
  48    if (!visinfo) {
  49       printf("Error: couldn't get an RGB, Double-buffered visual\n");
  50       exit(1);
  51    }
  52
  53    /* window attributes */
  54    attr.background_pixel = 0;
  55    attr.border_pixel = 0;
  56    /* TODO: share root colormap if possible */
  57    attr.colormap = XCreateColormap( dpy, root, visinfo->visual, AllocNone);
  58    attr.event_mask = StructureNotifyMask | ExposureMask;
  59    mask = CWBackPixel | CWBorderPixel | CWColormap | CWEventMask;
  60
  61    win = XCreateWindow( dpy, root, 0, 0, width, height,
  62                         0, visinfo->depth, InputOutput,
  63                         visinfo->visual, mask, &attr );
  64
  65    /* make an X GC so we can do XCopyArea later */
  66    gc = XCreateGC( dpy, win, 0, NULL );
  67
  68    ctx = glXCreateContext( dpy, visinfo, NULL, True );
  69
  70    return win;
  71 }
  72
  73
  74 static GLXPixmap make_pixmap( Display *dpy, Window win,
  75                                unsigned int width, unsigned int height )
  76 {
  77    Pixmap pm;
  78    GLXPixmap glxpm;
  79    XWindowAttributes attr;
  80
  81    pm = XCreatePixmap( dpy, win, width, height, visinfo->depth );
  82    XGetWindowAttributes( dpy, win, &attr );
  83
  84    /*
  85     * IMPORTANT:
  86     *   Use the glXCreateGLXPixmapMESA funtion when using Mesa because
  87     *   Mesa needs to know the colormap associated with a pixmap in order
  88     *   to render correctly.  This is because Mesa allows RGB rendering
  89     *   into any kind of visual, not just TrueColor or DirectColor.
  90     */
  91 #ifdef GLX_MESA_pixmap_colormap
  92    glxpm = glXCreateGLXPixmapMESA( dpy, visinfo, pm, attr.colormap );
  93 #else
  94    /* This will work with Mesa too if the visual is TrueColor or DirectColor */
  95    glxpm = glXCreateGLXPixmap( dpy, visinfo, pm );
  96 #endif
  97
  98    return glxpm;
  99 }
 100
 101
 102
 103 static void event_loop( Display *dpy, GLXPixmap pm )
 104 {
 105    XEvent event;
 106
 107    while (1) {
 108       XNextEvent( dpy, &event );
 109
 110       switch (event.type) {
 111          case Expose:
 112             printf("Redraw\n");
 113             /* copy the image from GLXPixmap to window */
 114             XCopyArea( dpy, pm, event.xany.window,  /* src, dest */
 115                        gc, 0, 0, 300, 300,          /* gc, src pos, size */
 116                        0, 0 );                      /* dest pos */
 117             break;
 118          case ConfigureNotify:
 119             /* nothing */
 120             break;
 121       }
 122    }
 123 }
 124
 125
 126
 127 int main( int argc, char *argv[] )
 128 {
 129    Display *dpy;
 130    Window win;
 131    GLXPixmap pm;
 132
 133    dpy = XOpenDisplay(NULL);
 134
 135    win = make_rgb_window( dpy, 300, 300 );
 136    pm = make_pixmap( dpy, win, 300, 300 );
 137
 138 #ifdef JUNK
 139    glXMakeCurrent( dpy, win, ctx );  /*to make sure ctx is properly initialized*/
 140 #endif
 141
 142    glXMakeCurrent( dpy, pm, ctx );
 143
 144    /* Render an image into the pixmap */
 145    glShadeModel( GL_FLAT );
 146    glClearColor( 0.5, 0.5, 0.5, 1.0 );
 147    glClear( GL_COLOR_BUFFER_BIT );
 148    glViewport( 0, 0, 300, 300 );
 149    glOrtho( -1.0, 1.0, -1.0, 1.0, -1.0, 1.0 );
 150    glColor3f( 0.0, 1.0, 1.0 );
 151    glRectf( -0.75, -0.75, 0.75, 0.75 );
 152    glFlush();
 153
 154    /* when a redraw is needed we'll just copy the pixmap image to the window */
 155
 156    XMapWindow( dpy, win );
 157
 158    event_loop( dpy, pm );
 159    return 0;
 160 }