Ack, that looks messy. Anyway, here's my current code----all the objects and checks are sucessful, right up to the creation of the GdkPixbuf, but the damn thing is blank---no image in it. I even glClear()'d the buffer to green so I'd know it was getting *something*, but.....nope.
configure-event handler:
gboolean reshapeGL(GtkWidget *widget, GdkEventConfigure *evnt, gpointer data)
{
GUIWindow* me = (GUIWindow*)data;
GdkGLContext *glcontext = gtk_widget_get_gl_context (widget);
GdkGLDrawable *gldrawable = gtk_widget_get_gl_drawable (widget);
assert(pthread_equal(me->mainthread, pthread_self()));
if (!gdk_gl_drawable_gl_begin (gldrawable, glcontext))
return FALSE;
me->lock();
me->viewport.x = evnt->x;
me->viewport.width = evnt->width;
me->viewport.y = evnt->y;
me->viewport.height = evnt->height;
me->unlock();
gdk_gl_drawable_gl_end (gldrawable);
if (me->osPixmap)
gdk_gl_pixmap_destroy(me->osPixmap);
if (me->osContext)
gdk_gl_context_destroy(me->osContext);
GdkPixmap *pixmap = gdk_pixmap_new (widget->window,
widget->allocation.width,
widget->allocation.height,
-1);
GdkGLConfig *glconfig = gdk_gl_config_new_by_mode (
GdkGLConfigMode(GDK_GL_MODE_RGB |
GDK_GL_MODE_SINGLE));
me->osPixmap = gdk_pixmap_set_gl_capability (pixmap,
glconfig,
NULL);
me->osContext = gdk_gl_context_new (GDK_GL_DRAWABLE(me->osPixmap),
glcontext,
FALSE,
GDK_GL_RGBA_TYPE);
g_object_unref(glconfig);
return FALSE;
}
And here's my function to generate the Pixbuf:
gboolean doTakeScreenshot(gpointer data)
{
GUIWindow *me = (GUIWindow*)data;
assert(pthread_equal(me->mainthread, pthread_self()));
me->lock();
GdkGLDrawable *osDrawable = GDK_GL_DRAWABLE(me->osPixmap);
if (!osDrawable || !me->osContext)
{
fprintf(stderr, "Warning, no offscreen pixbuf configured in GUIWindow::doTakeScreenshot.\n");
me->signal(&me->screenshot_complete);
me->unlock();
return FALSE;
}
if (!me->screenshot_dest)
{
fprintf(stderr, "Warning, no screenshot destination found in GUIWindow::doTakeScreenshot.\n");
me->signal(&me->screenshot_complete);
me->unlock();
return FALSE;
}
if (!gdk_gl_drawable_gl_begin (osDrawable, me->osContext))
{
me->signal(&me->screenshot_complete);
me->unlock();
return FALSE;
}
glViewport(me->viewport.x,me->viewport.y,me->viewport.width,me->viewport.height);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
fprintf(stderr,"Taking screenshot of window %d.\n",me->window_id);
// Need to flip the y axis for screenshots
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(me->ortho.x,me->ortho.x+me->ortho.width,
me->ortho.y+me->ortho.height,me->ortho.y,0,1);
glMatrixMode(GL_MODELVIEW);
glClearColor(0,1,0,1);
glClear(GL_COLOR_BUFFER_BIT);
glColor3d(1,0,0);
glBegin(GL_LINES);
glVertex2d(me->ortho.x,me->ortho.y+me->ortho.height);
glVertex2d(me->ortho.x+me->ortho.width,me->ortho.y);
glEnd();
gdk_gl_drawable_wait_gl(osDrawable);
gdk_gl_drawable_gl_end (osDrawable);
me->osBuffer = gdk_pixbuf_get_from_drawable(me->osBuffer,
gdk_gl_pixmap_get_pixmap(me->osPixmap),
NULL,//gdk_color_get_system(),
0,0,0,0,-1,-1);
if (me->osBuffer)
{
color_img *img = me->screenshot_dest;
int pbheight = gdk_pixbuf_get_height (me->osBuffer);
int pbwidth = gdk_pixbuf_get_width (me->osBuffer);
int pbstride = gdk_pixbuf_get_rowstride (me->osBuffer);
int pbchannels = gdk_pixbuf_get_n_channels(me->osBuffer);
unsigned char *pixels = gdk_pixbuf_get_pixels(me->osBuffer);
assert(pbchannels == 3);
for (int i = 0; i < pbheight; i++)
{
for (int j = 0; j < pbwidth; j++)
{
memcpy(img->data[i][j],pixels + i*pbstride + j*pbchannels, pbchannels);
img->data[i][j][3] = 255;
}
}
}
me->signal(&me->screenshot_complete);
me->unlock();
return FALSE;
}
I breakpoint on the line after the gdk_pixbuf_get_pixels() call, and check the first few bytes----always 0. They should be (0,1,0) patterns since that's what I cleared the background too, or (1,0,0) if I happened to get a pixel with the red line on it.
Any idea what's wrong? If I don't hear back I'm scrapping the pixmap code as worthless and going to the tried-and-true render-to-texture via EXT_framebuffer_object approach. Even if that does require introducing a GLEW dependency.
----- Original Message -----
From: Stephane Popinet <s.popinet@xxxxxxxxxx>
Date: Wednesday, August 26, 2009 5:20 pm
Subject: Re: [GtkGLExt] GdkGLPixmap troubles
> Hi Lindley, Jean,
>
> > Exporting a GL view is just a nightmare. Things seem to depend
> upon the
> > used driver. The solutioin I use can be seen at
> >
> http://svn.savannah.gnu.org/viewvc/trunk/gchemutils/libs/gcu/glview.cc?annotate=1098&root=gchemutils> starting from line 368. Not sure it works in all cases.
>
> Yes, I can confirm that doing offscreen openGL rendering in a portable
> way truly is a nightmare. It depends on the openGL driver and some
> drivers are so dodgy that they even tell you that they support
> offscreen openGL rendering when they don't.
>
> OSMesa is a good alternative, however it is not that well
> supported either...
>
> I would imagine offscreen openGL rendering to be something many people
> want to do but I am puzzled by the lack of ressources on the topic on
> the web. Are people using some other mechanism we are not aware of?
>
> Thanks for your code Jean, I will have a look and see if I can use it
> to improve mine (http://gfs.sf.net).
>
> cheers
>
> Stephane
> _______________________________________________
> gtkglext-list mailing list
> gtkglext-list@xxxxxxxxx
> http://mail.gnome.org/mailman/listinfo/gtkglext-list
>
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