New glxsnoop demo to display another window's z/stencil/back buffer.

diff --git a/progs/xdemos/Makefile b/progs/xdemos/Makefile
index c585026..4c4ecac 100644 (file)
--- a/progs/xdemos/Makefile
+++ b/progs/xdemos/Makefile
@@ -17,6 +17,7 @@ PROGS = glthreads \
        glxinfo \
        glxpixmap \
        glxpbdemo \
+       glxsnoop \
        glxswapcontrol \
        manywin \
        offset \

diff --git a/progs/xdemos/glxsnoop.c b/progs/xdemos/glxsnoop.c
new file mode 100644 (file)
index 0000000..2e95134
--- /dev/null
+++ b/progs/xdemos/glxsnoop.c
@@ -0,0 +1,377 @@
+/**
+ * Display/snoop the z/stencil/back/front buffers of another app's window.
+ * Also, an example of the need for shared ancillary renderbuffers.
+ *
+ * Hint: use 'xwininfo' to get a window's ID.
+ *
+ * Brian Paul
+ * 11 Oct 2007
+ */
+
+#define GL_GLEXT_PROTOTYPES
+
+#include <GL/gl.h>
+#include <GL/glx.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <X11/keysym.h>
+
+
+#define Z_BUFFER 1
+#define STENCIL_BUFFER 2
+#define BACK_BUFFER 3
+#define FRONT_BUFFER 4
+
+
+static int Buffer = BACK_BUFFER;
+static int WindowID = 0;
+static const char *DisplayName = NULL;
+static GLXContext Context = 0;
+static int Width, Height;
+
+
+/**
+ * Grab the z/stencil/back/front image from the srcWin and display it
+ * (possibly converted to grayscale) in the dstWin.
+ */
+static void
+redraw(Display *dpy, Window srcWin, Window dstWin )
+{
+   GLubyte *image = malloc(Width * Height * 4);
+
+   glXMakeCurrent(dpy, srcWin, Context);
+   glPixelStorei(GL_PACK_ALIGNMENT, 1);
+   if (Buffer == BACK_BUFFER) {
+      glReadBuffer(GL_BACK);
+      glReadPixels(0, 0, Width, Height, GL_RGBA, GL_UNSIGNED_BYTE, image);
+   }
+   else if (Buffer == FRONT_BUFFER) {
+      glReadBuffer(GL_FRONT);
+      glReadPixels(0, 0, Width, Height, GL_RGBA, GL_UNSIGNED_BYTE, image);
+   }
+   else if (Buffer == Z_BUFFER) {
+      GLfloat *z = malloc(Width * Height * sizeof(GLfloat));
+      int i;
+      glReadPixels(0, 0, Width, Height, GL_DEPTH_COMPONENT, GL_FLOAT, z);
+      for (i = 0; i < Width * Height; i++) {
+         image[i*4+0] =
+         image[i*4+1] =
+         image[i*4+2] = (GLint) (255.0 * z[i]);
+         image[i*4+3] = 255;
+      }
+      free(z);
+   }
+   else if (Buffer == STENCIL_BUFFER) {
+      GLubyte *sten = malloc(Width * Height * sizeof(GLubyte));
+      int i, min = 100, max = -1;
+      float step;
+      int sz;
+      glGetIntegerv(GL_STENCIL_BITS, &sz);
+      glReadPixels(0, 0, Width, Height,
+                   GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, sten);
+      /* find min/max for converting stencil to grayscale */
+      for (i = 0; i < Width * Height; i++) {
+         if (sten[i] < min)
+            min = sten[i];
+         if (sten[i] > max)
+            max = sten[i];
+      }
+      if (min == max)
+         step = 0;
+      else
+         step = 255.0 / (float) (max - min);
+      for (i = 0; i < Width * Height; i++) {
+         image[i*4+0] =
+         image[i*4+1] =
+         image[i*4+2] = (GLint) ((sten[i] - min) * step);
+         image[i*4+3] = 255;
+      }
+      free(sten);
+   }
+
+   glXMakeCurrent(dpy, dstWin, Context);
+   glWindowPos2iARB(0, 0);
+   glDrawBuffer(GL_FRONT);
+   glDrawPixels(Width, Height, GL_RGBA, GL_UNSIGNED_BYTE, image);
+   glFlush();
+
+   free(image);
+}
+
+
+static void
+set_window_title(Display *dpy, Window win, const char *title)
+{
+   XSizeHints sizehints;
+   sizehints.flags = 0;
+   XSetStandardProperties(dpy, win, title, title,
+                          None, (char **)NULL, 0, &sizehints);
+}
+
+
+static Window
+make_gl_window(Display *dpy, XVisualInfo *visinfo, int width, int height)
+{
+   int scrnum;
+   XSetWindowAttributes attr;
+   unsigned long mask;
+   Window root;
+   Window win;
+   int x = 0, y = 0;
+   char *name = NULL;
+
+   scrnum = DefaultScreen( dpy );
+   root = RootWindow( dpy, scrnum );
+
+   /* window attributes */
+   attr.background_pixel = 0;
+   attr.border_pixel = 0;
+   attr.colormap = XCreateColormap( dpy, root, visinfo->visual, AllocNone);
+   attr.event_mask = StructureNotifyMask | ExposureMask | KeyPressMask;
+   mask = CWBackPixel | CWBorderPixel | CWColormap | CWEventMask;
+
+   win = XCreateWindow( dpy, root, x, y, width, height,
+                       0, visinfo->depth, InputOutput,
+                       visinfo->visual, mask, &attr );
+
+   /* set hints and properties */
+   {
+      XSizeHints sizehints;
+      sizehints.x = x;
+      sizehints.y = y;
+      sizehints.width  = width;
+      sizehints.height = height;
+      sizehints.flags = USSize | USPosition;
+      XSetNormalHints(dpy, win, &sizehints);
+      XSetStandardProperties(dpy, win, name, name,
+                              None, (char **)NULL, 0, &sizehints);
+   }
+
+   return win;
+}
+
+
+static void
+update_window_title(Display *dpy, Window win)
+{
+   char title[1000], *buf;
+
+   switch (Buffer) {
+   case Z_BUFFER:
+      buf = "Z";
+      break;
+   case STENCIL_BUFFER:
+      buf = "Stencil";
+      break;
+   case BACK_BUFFER:
+      buf = "Back";
+      break;
+   case FRONT_BUFFER:
+      buf = "Front";
+      break;
+   default:
+      buf = "";
+   }
+
+   sprintf(title, "glxsnoop window 0x%x (%s buffer)", (int) WindowID, buf);
+
+   set_window_title(dpy, win, title);
+}
+
+
+static void
+keypress(Display *dpy, Window win, char key)
+{
+   switch (key) {
+   case 27:
+      /* escape */
+      exit(0);
+      break;
+   case 's':
+      Buffer = STENCIL_BUFFER;
+      break;
+   case 'z':
+      Buffer = Z_BUFFER;
+      break;
+   case 'f':
+      Buffer = FRONT_BUFFER;
+      break;
+   case 'b':
+      Buffer = BACK_BUFFER;
+      break;
+   default:
+      return;
+   }
+
+   update_window_title(dpy, win);
+   redraw(dpy, WindowID, win);
+}
+
+
+static void
+event_loop(Display *dpy, Window win)
+{
+   XEvent event;
+
+   while (1) {
+      XNextEvent( dpy, &event );
+
+      switch (event.type) {
+      case Expose:
+         redraw(dpy, WindowID, win);
+         break;
+      case ConfigureNotify:
+         /*resize( event.xconfigure.width, event.xconfigure.height );*/
+         break;
+      case KeyPress:
+         {
+            char buffer[10];
+            int r, code;
+            code = XLookupKeysym(&event.xkey, 0);
+            if (code == XK_Left) {
+            }
+            else {
+               r = XLookupString(&event.xkey, buffer, sizeof(buffer),
+                                 NULL, NULL);
+               keypress(dpy, win, buffer[0]);
+            }
+         }
+      default:
+         /* nothing */
+         ;
+      }
+   }
+}
+
+
+static VisualID
+get_window_visualid(Display *dpy, Window win)
+{
+   XWindowAttributes attr;
+
+   if (XGetWindowAttributes(dpy, win, &attr)) {
+      return attr.visual->visualid;
+   }
+   else {
+      return 0;
+   }
+}
+
+
+static void
+get_window_size(Display *dpy, Window win, int *w, int *h)
+{
+   XWindowAttributes attr;
+
+   if (XGetWindowAttributes(dpy, win, &attr)) {
+      *w = attr.width;
+      *h = attr.height;
+   }
+   else {
+      *w = *h = 0;
+   }
+}
+
+
+static XVisualInfo *
+visualid_to_visualinfo(Display *dpy, VisualID vid)
+{
+   XVisualInfo *vinfo, templ;
+   long mask;
+   int n;
+
+   templ.visualid = vid;
+   mask = VisualIDMask;
+
+   vinfo = XGetVisualInfo(dpy, mask, &templ, &n);
+   return vinfo;
+}
+
+
+static void
+key_usage(void)
+{
+   printf("Keyboard:\n");
+   printf("  z - display Z buffer\n");
+   printf("  s - display stencil buffer\n");
+   printf("  f - display front color buffer\n");
+   printf("  b - display back buffer\n");
+}
+
+
+static void
+usage(void)
+{
+   printf("Usage: glxsnoop [-display dpy] windowID\n");
+   key_usage();
+}
+
+
+static void
+parse_opts(int argc, char *argv[])
+{
+   int i;
+
+   for (i = 1; i < argc; i++) {
+      if (strcmp(argv[i], "-h") == 0) {
+         usage();
+         exit(0);
+      }
+      else if (strcmp(argv[i], "-display") == 0) {
+         DisplayName = argv[i + 1];
+         i++;
+      }
+      else {
+         if (argv[i][0] == '0' && argv[i][1] == 'x') {
+            /* hex */
+            WindowID = strtol(argv[i], NULL, 16);
+         }
+         else {
+            WindowID = atoi(argv[i]);
+         }
+         break;
+      }
+   }
+
+   if (!WindowID) {
+      usage();
+      exit(0);
+   }
+}
+
+
+int
+main( int argc, char *argv[] )
+{
+   Display *dpy;
+   VisualID vid;
+   XVisualInfo *visinfo;
+   Window win;
+
+   parse_opts(argc, argv);
+
+   key_usage();
+
+   dpy = XOpenDisplay(DisplayName);
+
+   /* find the VisualID for the named window */
+   vid = get_window_visualid(dpy, WindowID);
+   get_window_size(dpy, WindowID, &Width, &Height);
+
+   visinfo = visualid_to_visualinfo(dpy, vid);
+
+   Context = glXCreateContext( dpy, visinfo, NULL, True );
+   if (!Context) {
+      printf("Error: glXCreateContext failed\n");
+      exit(1);
+   }
+
+   win = make_gl_window(dpy, visinfo, Width, Height);
+   XMapWindow(dpy, win);
+   update_window_title(dpy, win);
+
+   event_loop( dpy, win );
+
+   return 0;
+}