progs/xdemos/xdemo.c

/*
 * Very simple demo of how to use the Mesa/X11 interface instead of the
 * glx, tk or aux toolkits.  I highly recommend using the GLX interface
 * instead of the X/Mesa interface, however.
 *
 * This program is in the public domain.
 *
 * Brian Paul
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include "GL/xmesa.h"
#include "GL/gl.h"



static GLint Black, Red, Green, Blue;



static void make_window( char *title, int color_flag )
{
   int x = 10, y = 10, width = 400, height = 300;
   Display *dpy;
   int scr;
   Window root, win;
   Colormap cmap;
   XColor xcolor;
   int attr_flags;
   XVisualInfo *visinfo;
   XSetWindowAttributes attr;
   XTextProperty tp;
   XSizeHints sh;
   XEvent e;
   XMesaContext context;
   XMesaVisual visual;
   XMesaBuffer buffer;


   /*
    * Do the usual X things to make a window.
    */

   dpy = XOpenDisplay(NULL);
   if (!dpy) {
      printf("Couldn't open default display!\n");
      exit(1);
   }

   scr = DefaultScreen(dpy);
   root = RootWindow(dpy, scr);

   /* alloc visinfo struct */
   visinfo = (XVisualInfo *) malloc( sizeof(XVisualInfo) );

   /* Get a visual and colormap */
   if (color_flag) {
      /* Open TrueColor window */

/*
      if (!XMatchVisualInfo( dpy, scr, 24, TrueColor, visinfo )) {
	 printf("Couldn't get 24-bit TrueColor visual!\n");
	 exit(1);
      }
*/
      if (!XMatchVisualInfo( dpy, scr, 8, PseudoColor, visinfo )) {
	 printf("Couldn't get 8-bit PseudoColor visual!\n");
	 exit(1);
      }

      cmap = XCreateColormap( dpy, root, visinfo->visual, AllocNone );
      Black = Red = Green = Blue = 0;
   }
   else {
      /* Open color index window */

      if (!XMatchVisualInfo( dpy, scr, 8, PseudoColor, visinfo )) {
	 printf("Couldn't get 8-bit PseudoColor visual\n");
	 exit(1);
      }

      cmap = XCreateColormap( dpy, root, visinfo->visual, AllocNone );

      /* Allocate colors */
      xcolor.red   = 0x0;
      xcolor.green = 0x0;
      xcolor.blue  = 0x0;
      xcolor.flags = DoRed | DoGreen | DoBlue;
      if (!XAllocColor( dpy, cmap, &xcolor )) {
	 printf("Couldn't allocate black!\n");
	 exit(1);
      }
      Black = xcolor.pixel;

      xcolor.red   = 0xffff;
      xcolor.green = 0x0;
      xcolor.blue  = 0x0;
      xcolor.flags = DoRed | DoGreen | DoBlue;
      if (!XAllocColor( dpy, cmap, &xcolor )) {
	 printf("Couldn't allocate red!\n");
	 exit(1);
      }
      Red = xcolor.pixel;

      xcolor.red   = 0x0;
      xcolor.green = 0xffff;
      xcolor.blue  = 0x0;
      xcolor.flags = DoRed | DoGreen | DoBlue;
      if (!XAllocColor( dpy, cmap, &xcolor )) {
	 printf("Couldn't allocate green!\n");
	 exit(1);
      }
      Green = xcolor.pixel;

      xcolor.red   = 0x0;
      xcolor.green = 0x0;
      xcolor.blue  = 0xffff;
      xcolor.flags = DoRed | DoGreen | DoBlue;
      if (!XAllocColor( dpy, cmap, &xcolor )) {
	 printf("Couldn't allocate blue!\n");
	 exit(1);
      }
      Blue = xcolor.pixel;
   }

   /* set window attributes */
   attr.colormap = cmap;
   attr.event_mask = ExposureMask | StructureNotifyMask;
   attr.border_pixel = BlackPixel( dpy, scr );
   attr.background_pixel = BlackPixel( dpy, scr );
   attr_flags = CWColormap | CWEventMask | CWBorderPixel | CWBackPixel;

   /* Create the window */
   win = XCreateWindow( dpy, root, x,y, width, height, 0,
			    visinfo->depth, InputOutput,
			    visinfo->visual,
			    attr_flags, &attr);
   if (!win) {
      printf("Couldn't open window!\n");
      exit(1);
   }

   XStringListToTextProperty(&title, 1, &tp);
   sh.flags = USPosition | USSize;
   XSetWMProperties(dpy, win, &tp, &tp, 0, 0, &sh, 0, 0);
   XMapWindow(dpy, win);
   while (1) {
      XNextEvent( dpy, &e );
      if (e.type == MapNotify && e.xmap.window == win) {
	 break;
      }
   }


   /*
    * Now do the special Mesa/Xlib stuff!
    */

   visual = XMesaCreateVisual( dpy, visinfo,
                              (GLboolean) color_flag,
                               GL_FALSE,  /* alpha_flag */
                               GL_FALSE,  /* db_flag */
                               GL_FALSE,  /* stereo flag */
                               GL_FALSE,  /* ximage_flag */
                               0,         /* depth size */
                               0,         /* stencil size */
                               0,0,0,0,   /* accum_size */
                               0,         /* num samples */
                               0,         /* level */
                               0          /* caveat */
                              );
   if (!visual) {
      printf("Couldn't create Mesa/X visual!\n");
      exit(1);
   }

   /* Create a Mesa rendering context */
   context = XMesaCreateContext( visual,
                                 NULL       /* share_list */
                               );
   if (!context) {
      printf("Couldn't create Mesa/X context!\n");
      exit(1);
   }

   buffer = XMesaCreateWindowBuffer( visual, win );
   if (!buffer) {
      printf("Couldn't create Mesa/X buffer!\n");
      exit(1);
   }


   XMesaMakeCurrent( context, buffer );

   /* Ready to render! */
}



static void draw_cube( void )
{
   /* X faces */
   glIndexi( Red );
   glColor3f( 1.0, 0.0, 0.0 );
   glBegin( GL_POLYGON );
   glVertex3f( 1.0, 1.0, 1.0 );
   glVertex3f( 1.0, -1.0, 1.0 );
   glVertex3f( 1.0, -1.0, -1.0 );
   glVertex3f( 1.0, 1.0, -1.0 );
   glEnd();

   glBegin( GL_POLYGON );
   glVertex3f( -1.0, 1.0, 1.0 );
   glVertex3f( -1.0, 1.0, -1.0 );
   glVertex3f( -1.0, -1.0, -1.0 );
   glVertex3f( -1.0, -1.0, 1.0 );
   glEnd();

   /* Y faces */
   glIndexi( Green );
   glColor3f( 0.0, 1.0, 0.0 );
   glBegin( GL_POLYGON );
   glVertex3f(  1.0, 1.0,  1.0 );
   glVertex3f(  1.0, 1.0, -1.0 );
   glVertex3f( -1.0, 1.0, -1.0 );
   glVertex3f( -1.0, 1.0,  1.0 );
   glEnd();

   glBegin( GL_POLYGON );
   glVertex3f(  1.0, -1.0,  1.0 );
   glVertex3f( -1.0, -1.0,  1.0 );
   glVertex3f( -1.0, -1.0, -1.0 );
   glVertex3f(  1.0, -1.0, -1.0 );
   glEnd();

   /* Z faces */
   glIndexi( Blue );
   glColor3f( 0.0, 0.0, 1.0 );
   glBegin( GL_POLYGON );
   glVertex3f(  1.0,  1.0,  1.0 );
   glVertex3f( -1.0,  1.0,  1.0 );
   glVertex3f( -1.0, -1.0,  1.0 );
   glVertex3f(  1.0, -1.0,  1.0 );
   glEnd();

   glBegin( GL_POLYGON );
   glVertex3f(  1.0, 1.0, -1.0 );
   glVertex3f(  1.0,-1.0, -1.0 );
   glVertex3f( -1.0,-1.0, -1.0 );
   glVertex3f( -1.0, 1.0, -1.0 );
   glEnd();
}




static void display_loop( void )
{
   GLfloat xrot, yrot, zrot;

   xrot = yrot = zrot = 0.0;

   glClearColor( 0.0, 0.0, 0.0, 0.0 );
   glClearIndex( Black );

   glMatrixMode( GL_PROJECTION );
   glLoadIdentity();
   glFrustum( -1.0, 1.0,  -1.0, 1.0,  1.0, 10.0 );
   glTranslatef( 0.0, 0.0, -5.0 );

   glMatrixMode( GL_MODELVIEW );
   glLoadIdentity();

   glCullFace( GL_BACK );
   glEnable( GL_CULL_FACE );

   glShadeModel( GL_FLAT );

   while (1) {
      glClear( GL_COLOR_BUFFER_BIT );
      glPushMatrix();
      glRotatef( xrot, 1.0, 0.0, 0.0 );
      glRotatef( yrot, 0.0, 1.0, 0.0 );
      glRotatef( zrot, 0.0, 0.0, 1.0 );

      draw_cube();

      glPopMatrix();
      glFinish();

      xrot += 10.0;
      yrot += 7.0;
      zrot -= 3.0;
   }

}




int main( int argc, char *argv[] )
{
   int mode = 0;

   if (argc >= 2)
   {
        if (strcmp(argv[1],"-ci")==0)
           mode = 0;
        else if (strcmp(argv[1],"-rgb")==0)
           mode = 1;
        else
        {
           printf("Bad flag: %s\n", argv[1]);
           printf("Specify -ci for 8-bit color index or -rgb for RGB mode\n");
           exit(1);
        }
   }
   else
   {
        printf("Specify -ci for 8-bit color index or -rgb for RGB mode\n");
        printf("Defaulting to  8-bit color index\n");
   }

   make_window( argv[0], mode );

   display_loop();
   return 0;
}