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1. Help, ./configure does not find Mesa, I do have Mesa libaries installed.
- Mesa may need additional libraries to link with, depending on what
options were used while compiling Mesa libraries. Currently configure tries
to link Mesa with whatever libraries GTK needs and if this fails it tries
Mesa+needed by GTK+pthreads libraries. Try passing extra libraries to
./configure in LIBS envinronment variable.
- configure scripts are still a bit flaky, patches are gratefully accepted.
2. How do I make any widget opengl widget?
Your widget needs OpenGL capable visual and you also
need to set colormap for it. Widget must also have
X window (not all widgets have it).
/* get visual using gdk_gl_choose_visual */
visual = gdk_gl_choose_visual(visual_attributes);
/* set visual and colormap */
gtk_widget_push__colormap(gdk_colormap_new(visual, TRUE));
gtk_widget_push_visual(visual);
/* create your widget */
widget = gtk_foobar_new();
/* disable backing store (only in GTK-1.4) */
gtk_widget_set_double_buffered(widget, FALSE);
/* restore old values */
gtk_widget_pop_visual();
gtk_widget_pop_colormap();
3. How do I render to such widget?
Create gl context and connect it to widgets GdkDrawable.
context = gdk_gl_context(visual);
/* connect to gdk window of widget */
if (gdk_gl_make_current(widget->window, context)) {
do opengl stuff...
}
4. How do I render to off screen pixmap?
See examples/glpixmap.c, remember that pixmaps can not be rendered to with
direct context.
5. Can I use gdk_gl functions and GtkGLArea widget in the same program?
Yes, just remember that gtk_gl_area_make_current makes internal context of
GtkGLArea widget current context (and leaves it so).
6. How do I capture keypress events for GtkGLArea widget?
This is not a GtkGLArea specific question, but here is the answer anyway,
- You forgot to set event mask:
gtk_widget_set_events(glarea, GDK_KEY_PRESS_MASK);
- You forgot to grab focus:
GTK_WIDGET_SET_FLAGS(glarea, GTK_CAN_FOCUS);
gtk_widget_grab_focus(GTK_WIDGET(glarea));
- keypresses/releases have default handlers, you may need to prevent
them from running:
/* do this in your signal keypress handler and return TRUE from handler */
gtk_signal_emit_stop_by_name(GTK_OBJECT(glarea),"key_press_event");
7. I noticed that gtk_gl_area_begingl(), gtk_gl_area_endgl(), and gtk_gl_area_swapbuffers()
are deprecated?
- they are still there, but you should use gtk_gl_area_make_current() instead
then you can avoid calling matching gtk_gl_area_endgl().
- just formalizing what has been true for a long time, gtk_gl_area_endgl is
no longer necessary and gtk_gl_area_begingl() just makes widgets context
current.
- gtk_gl_area_swapbuffers() just fixes minor spelling error.
- old versions wont go away.
- to convert your code you can replace them with following functions.
gtk_gl_area_begingl() => gtk_gl_area_make_current()
gtk_gl_area_endgl() => glFlush() or nothing
gtk_gl_area_swapbuffers() => gtk_gl_area_swap_buffers()
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