diff options
| -rw-r--r-- | documentation/opengl.html | 27 |
1 files changed, 22 insertions, 5 deletions
diff --git a/documentation/opengl.html b/documentation/opengl.html index 807908a68..5ed567992 100644 --- a/documentation/opengl.html +++ b/documentation/opengl.html @@ -17,13 +17,31 @@ include the file <TT><GL/gl.h></TT>, define some extra drawing functions provided by FLTK, and include the <TT><windows.h></TT> header file needed by WIN32 applications. </P> <H2>Making a Subclass of Fl_Gl_Window</H2> - To make a subclass of Fl_Gl_Window, you must provide: +To make a subclass of Fl_Gl_Window, you must provide: <UL> <LI>A class definition. </LI> <LI>A <TT>draw()</TT> method. </LI> <LI>A <TT>handle()</TT> method (if you need to recieve input from the user). </LI> </UL> +If your subclass provides static controls in the window, they must be +redrawn whenever the <tt>FL_DAMAGE_ALL</tt> bit is set in the value +returned by <tt>damage()</tt>. For double-buffered windows you will +need to surround the drawing code with the following code to make sure +that both buffers are redrawn: +<ul><pre> +#ifndef MESA +glDrawBuffer(GL_FRONT_AND_BACK); +#endif // !MESA +... draw stuff here ... +#ifndef MESA +glDrawBuffer(GL_BACK); +#endif // !MESA +</pre></ul> +<B>Note:</B> If you are using the Mesa graphics library, the call to +<tt>glDrawBuffer()</tt> is not required and will slow down drawing +considerably. The preprocessor instructions shown above will optimize +your code based upon the graphics library used. <H3>Defining the Subclass</H3> To define the subclass you just subclass the <TT>Fl_Gl_Window</TT> class: <UL> @@ -163,12 +181,11 @@ for maximum portability: </P> <UL> <LI>You must choose a default visual with <A href=functions.html#gl_visual> <TT>Fl::gl_visual()</TT></A>. </LI> -<LI>You cannot pass <TT>FL_DOUBLE</TT> to <TT>Fl::gl_visual()</TT>. </LI> -<LI>You cannot use <TT>Fl_Double_Window</TT> or <TT>Fl_Overlay_Window</TT> -. </LI> +<LI>You cannot pass <TT>FL_DOUBLE</TT> to <TT>Fl::gl_visual()</TT>.</LI> +<LI>You cannot use <TT>Fl_Double_Window</TT> or <TT>Fl_Overlay_Window</TT>.</LI> </UL> Do <I>not</I> call <TT>gl_start()</TT> or <TT>gl_finish()</TT> when -drawing into an <TT>Fl_Gl_Window</TT>! +drawing into an <TT>Fl_Gl_Window</TT>! <H2>OpenGL Drawing Functions</H2> FLTK provides some useful OpenGL drawing functions. They can be freely mixed with any OpenGL calls, and are defined by including <TT> |