Initial revision

progs/xdemos/glxpixmap.c

@@ -0,0 +1,160 @@
+/* $Id: glxpixmap.c,v 1.1 1999/08/19 00:55:43 jtg Exp $ */
+
+
+/*
+ * A demonstration of using the GLXPixmap functions.  This program is in
+ * the public domain.
+ *
+ * Brian Paul
+ */
+
+
+/*
+ * $Id: glxpixmap.c,v 1.1 1999/08/19 00:55:43 jtg Exp $
+ */
+
+
+#include <GL/gl.h>
+#include <GL/glx.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+
+
+static GLXContext ctx;
+static XVisualInfo *visinfo;
+static GC gc;
+
+
+
+static Window make_rgb_window( Display *dpy,
+				  unsigned int width, unsigned int height )
+{
+   int attrib[] = { GLX_RGBA,
+		    GLX_RED_SIZE, 1,
+		    GLX_GREEN_SIZE, 1,
+		    GLX_BLUE_SIZE, 1,
+		    None };
+   int scrnum;
+   XSetWindowAttributes attr;
+   unsigned long mask;
+   Window root;
+   Window win;
+
+   scrnum = DefaultScreen( dpy );
+   root = RootWindow( dpy, scrnum );
+
+   visinfo = glXChooseVisual( dpy, scrnum, attrib );
+   if (!visinfo) {
+      printf("Error: couldn't get an RGB, Double-buffered visual\n");
+      exit(1);
+   }
+
+   /* window attributes */
+   attr.background_pixel = 0;
+   attr.border_pixel = 0;
+   /* TODO: share root colormap if possible */
+   attr.colormap = XCreateColormap( dpy, root, visinfo->visual, AllocNone);
+   attr.event_mask = StructureNotifyMask | ExposureMask;
+   mask = CWBackPixel | CWBorderPixel | CWColormap | CWEventMask;
+
+   win = XCreateWindow( dpy, root, 0, 0, width, height,
+		        0, visinfo->depth, InputOutput,
+		        visinfo->visual, mask, &attr );
+
+   /* make an X GC so we can do XCopyArea later */
+   gc = XCreateGC( dpy, win, 0, NULL );
+
+   ctx = glXCreateContext( dpy, visinfo, NULL, True );
+
+   return win;
+}
+
+
+static GLXPixmap make_pixmap( Display *dpy, Window win,
+			       unsigned int width, unsigned int height )
+{
+   Pixmap pm;
+   GLXPixmap glxpm;
+   XWindowAttributes attr;
+
+   pm = XCreatePixmap( dpy, win, width, height, visinfo->depth );
+   XGetWindowAttributes( dpy, win, &attr );
+
+   /*
+    * IMPORTANT:
+    *   Use the glXCreateGLXPixmapMESA funtion when using Mesa because
+    *   Mesa needs to know the colormap associated with a pixmap in order
+    *   to render correctly.  This is because Mesa allows RGB rendering
+    *   into any kind of visual, not just TrueColor or DirectColor.
+    */
+#ifdef GLX_MESA_pixmap_colormap
+   glxpm = glXCreateGLXPixmapMESA( dpy, visinfo, pm, attr.colormap );
+#else
+   /* This will work with Mesa too if the visual is TrueColor or DirectColor */
+   glxpm = glXCreateGLXPixmap( dpy, visinfo, pm );
+#endif
+
+   return glxpm;
+}
+
+
+
+static void event_loop( Display *dpy, GLXPixmap pm )
+{
+   XEvent event;
+
+   while (1) {
+      XNextEvent( dpy, &event );
+
+      switch (event.type) {
+	 case Expose:
+	    printf("Redraw\n");
+	    /* copy the image from GLXPixmap to window */
+	    XCopyArea( dpy, pm, event.xany.window,  /* src, dest */
+		       gc, 0, 0, 300, 300,          /* gc, src pos, size */
+		       0, 0 );                      /* dest pos */
+	    break;
+	 case ConfigureNotify:
+	    /* nothing */
+	    break;
+      }
+   }
+}
+
+
+
+int main( int argc, char *argv[] )
+{
+   Display *dpy;
+   Window win;
+   GLXPixmap pm;
+
+   dpy = XOpenDisplay(NULL);
+
+   win = make_rgb_window( dpy, 300, 300 );
+   pm = make_pixmap( dpy, win, 300, 300 );
+
+#ifdef JUNK
+   glXMakeCurrent( dpy, win, ctx );  /*to make sure ctx is properly initialized*/
+#endif
+
+   glXMakeCurrent( dpy, pm, ctx );
+
+   /* Render an image into the pixmap */
+   glShadeModel( GL_FLAT );
+   glClearColor( 0.5, 0.5, 0.5, 1.0 );
+   glClear( GL_COLOR_BUFFER_BIT );
+   glViewport( 0, 0, 300, 300 );
+   glOrtho( -1.0, 1.0, -1.0, 1.0, -1.0, 1.0 );
+   glColor3f( 0.0, 1.0, 1.0 );
+   glRectf( -0.75, -0.75, 0.75, 0.75 );
+   glFlush();
+
+   /* when a redraw is needed we'll just copy the pixmap image to the window */
+
+   XMapWindow( dpy, win );
+
+   event_loop( dpy, pm );
+   return 0;
+}