progs/xdemos/glxpixmap.c

   1
   2
   3 /*
   4  * A demonstration of using the GLXPixmap functions.  This program is in
   5  * the public domain.
   6  *
   7  * Brian Paul
   8  */
   9
  10
  11 #include <GL/gl.h>
  12 #define GLX_GLXEXT_PROTOTYPES
  13 #include <GL/glx.h>
  14 #include <stdio.h>
  15 #include <stdlib.h>
  16 #include <string.h>
  17
  18
  19 static GLXContext ctx;
  20 static XVisualInfo *visinfo;
  21 static GC gc;
  22
  23
  24
  25 static Window make_rgb_window( Display *dpy,
  26                                   unsigned int width, unsigned int height )
  27 {
  28    const int sbAttrib[] = { GLX_RGBA,
  29                             GLX_RED_SIZE, 1,
  30                             GLX_GREEN_SIZE, 1,
  31                             GLX_BLUE_SIZE, 1,
  32                             None };
  33    const int dbAttrib[] = { GLX_RGBA,
  34                             GLX_RED_SIZE, 1,
  35                             GLX_GREEN_SIZE, 1,
  36                             GLX_BLUE_SIZE, 1,
  37                             GLX_DOUBLEBUFFER,
  38                             None };
  39    int scrnum;
  40    XSetWindowAttributes attr;
  41    unsigned long mask;
  42    Window root;
  43    Window win;
  44
  45    scrnum = DefaultScreen( dpy );
  46    root = RootWindow( dpy, scrnum );
  47
  48    visinfo = glXChooseVisual( dpy, scrnum, (int *) sbAttrib );
  49    if (!visinfo) {
  50       visinfo = glXChooseVisual( dpy, scrnum, (int *) dbAttrib );
  51       if (!visinfo) {
  52          printf("Error: couldn't get an RGB visual\n");
  53          exit(1);
  54       }
  55    }
  56
  57    /* window attributes */
  58    attr.background_pixel = 0;
  59    attr.border_pixel = 0;
  60    /* TODO: share root colormap if possible */
  61    attr.colormap = XCreateColormap( dpy, root, visinfo->visual, AllocNone);
  62    attr.event_mask = StructureNotifyMask | ExposureMask;
  63    mask = CWBackPixel | CWBorderPixel | CWColormap | CWEventMask;
  64
  65    win = XCreateWindow( dpy, root, 0, 0, width, height,
  66                         0, visinfo->depth, InputOutput,
  67                         visinfo->visual, mask, &attr );
  68
  69    /* make an X GC so we can do XCopyArea later */
  70    gc = XCreateGC( dpy, win, 0, NULL );
  71
  72    /* need indirect context */
  73    ctx = glXCreateContext( dpy, visinfo, NULL, False );
  74    if (!ctx) {
  75       printf("Error: glXCreateContext failed\n");
  76       exit(-1);
  77    }
  78
  79    printf("Direct rendering: %s\n", glXIsDirect(dpy, ctx) ? "Yes" : "No");
  80
  81    return win;
  82 }
  83
  84
  85 static GLXPixmap make_pixmap( Display *dpy, Window win,
  86                                unsigned int width, unsigned int height,
  87                                Pixmap *pixmap)
  88 {
  89    Pixmap pm;
  90    GLXPixmap glxpm;
  91    XWindowAttributes attr;
  92
  93    pm = XCreatePixmap( dpy, win, width, height, visinfo->depth );
  94    if (!pm) {
  95       printf("Error: XCreatePixmap failed\n");
  96       exit(-1);
  97    }
  98
  99    XGetWindowAttributes( dpy, win, &attr );
 100
 101    /*
 102     * IMPORTANT:
 103     *   Use the glXCreateGLXPixmapMESA funtion when using Mesa because
 104     *   Mesa needs to know the colormap associated with a pixmap in order
 105     *   to render correctly.  This is because Mesa allows RGB rendering
 106     *   into any kind of visual, not just TrueColor or DirectColor.
 107     */
 108 #ifdef GLX_MESA_pixmap_colormap
 109    if (strstr(glXQueryExtensionsString(dpy, 0), "GLX_MESA_pixmap_colormap")) {
 110       /* stand-alone Mesa, specify the colormap */
 111       glxpm = glXCreateGLXPixmapMESA( dpy, visinfo, pm, attr.colormap );
 112    }
 113    else {
 114       glxpm = glXCreateGLXPixmap( dpy, visinfo, pm );
 115    }
 116 #else
 117    /* This will work with Mesa too if the visual is TrueColor or DirectColor */
 118    glxpm = glXCreateGLXPixmap( dpy, visinfo, pm );
 119 #endif
 120
 121    if (!glxpm) {
 122       printf("Error: GLXCreateGLXPixmap failed\n");
 123       exit(-1);
 124    }
 125
 126    *pixmap = pm;
 127
 128    return glxpm;
 129 }
 130
 131
 132
 133 static void event_loop( Display *dpy, GLXPixmap pm )
 134 {
 135    XEvent event;
 136
 137    while (1) {
 138       XNextEvent( dpy, &event );
 139
 140       switch (event.type) {
 141          case Expose:
 142             printf("Redraw\n");
 143             /* copy the image from GLXPixmap to window */
 144             XCopyArea( dpy, pm, event.xany.window,  /* src, dest */
 145                        gc, 0, 0, 300, 300,          /* gc, src pos, size */
 146                        0, 0 );                      /* dest pos */
 147             break;
 148          case ConfigureNotify:
 149             /* nothing */
 150             break;
 151       }
 152    }
 153 }
 154
 155
 156
 157 int main( int argc, char *argv[] )
 158 {
 159    Display *dpy;
 160    Window win;
 161    Pixmap pm;
 162    GLXPixmap glxpm;
 163
 164    dpy = XOpenDisplay(NULL);
 165
 166    win = make_rgb_window( dpy, 300, 300 );
 167    glxpm = make_pixmap( dpy, win, 300, 300, &pm );
 168
 169    glXMakeCurrent( dpy, glxpm, ctx );
 170    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 171
 172    /* Render an image into the pixmap */
 173    glShadeModel( GL_FLAT );
 174    glClearColor( 0.5, 0.5, 0.5, 1.0 );
 175    glClear( GL_COLOR_BUFFER_BIT );
 176    glViewport( 0, 0, 300, 300 );
 177    glOrtho( -1.0, 1.0, -1.0, 1.0, -1.0, 1.0 );
 178    glColor3f( 0.0, 1.0, 1.0 );
 179    glRectf( -0.75, -0.75, 0.75, 0.75 );
 180    glFlush();
 181    glXWaitGL();
 182
 183    XMapWindow( dpy, win );
 184
 185    event_loop( dpy, pm );
 186    return 0;
 187 }