Re: Animation in GTK

["Timothy M. Shead" <tshead k-3d com>]

CyborgHead netscape net wrote:

> Hi
>     I am writing a game and have to use GTK. THe game is similar to 
Robot Battle for Windows (www.RobotBattle.com) On screen there are up to 
6 tanks, numerous bullets, mines and health kits. The graphics are very 
simple, looking from above.
>     I tried numerous ways to program the simple amimation needed to 
represent the battle between the robots. My first was was as follows
>
> //Colour Background
> gdk_gc_set_foreground( plot_gc , color + 0 );       
> gdk_draw_polygon( GTK_WIDGET(work_area)->window, plot_gc, fillin, 
map_vertices, 4);
> //Color Tank
> gdk_gc_set_foreground( plot_gc , color + 2 );
> gdk_draw_polygon( GTK_WIDGET(work_area)->window, plot_gc, fillin, 
tank, 4);
> //Color Gun
> gdk_gc_set_foreground( plot_gc , color + 3 );
> gdk_draw_polygon( GTK_WIDGET(work_area)->window, plot_gc, TRUE, gun, 4);
>    
> //Draw Wheels
> gdk_gc_set_foreground( plot_gc , color + 1 );
> gdk_draw_polygon( GTK_WIDGET(work_area)->window, plot_gc, TRUE, 
wheel1,4);
> gdk_gc_set_foreground( plot_gc , color + 1 );
> gdk_draw_polygon( GTK_WIDGET(work_area)->window, plot_gc, TRUE,wheel2,4);
> gdk_colormap_free_colors( colormap, color, 4 );
>
> This doesn't work, it flickers continully.
> I then tried to place the onscreen image in a pixmap, but this is to 
slow. I think that pixmaps are only supposed to be used for static 
images, not realtime movement. The position if the tanks is updated many 
times a second by a idle function.
>
> Does anyone know how to get smooth fast animation using GTK. It does 
not have to look great, just once you can see what is going on.

I'd suggest using OpenGL, since it's

a) A simple, clean API.
b) Your code will be portable to other platforms / toolkits.
c) OpenGL's transformations will simplify your code significantly -
drawing the tanks and their turrets at different angles becomes trivial.
d) Easily double-buffered.

Incorporating OpenGL in a GTK+ program is easy - try using GtkGLArea or
the SDPGTK library (www.k-3d.com).

Tim Shead