fltk/FL/Fl_Gl_Window.H

//
// "$Id$"
//
// OpenGL header file for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2008 by Bill Spitzak and others.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Library General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
// USA.
//
// Please report all bugs and problems on the following page:
//
//     http://www.fltk.org/str.php
//

/** \file
   Fl_Gl_Window widget . */

#ifndef Fl_Gl_Window_H
#define Fl_Gl_Window_H

#include "Fl_Window.H"

#ifndef GLContext
typedef void* GLContext; // actually a GLXContext or HGLDC
#endif

class Fl_Gl_Choice; // structure to hold result of glXChooseVisual

/**
  The Fl_Gl_Window widget sets things up so OpenGL works, and
  also keeps an OpenGL "context" for that window, so that changes to the
  lighting and projection may be reused between redraws. Fl_Gl_Window
  also flushes the OpenGL streams and swaps buffers after draw()
  returns.
  <P>OpenGL hardware typically provides some overlay bit planes, which
  are very useful for drawing UI controls atop your 3D graphics.  If the
  overlay hardware is not provided, FLTK tries to simulate the overlay,
  This works pretty well if your graphics are double buffered, but not
  very well for single-buffered. </P>
  <P>Please note that the FLTK drawing and clipping functions
  will not work inside an Fl_Gl_Window. All drawing
  should be done using OpenGL calls exclusively.
  Even though Fl_Gl_Window is derived from Fl_Group, 
  it is not useful to add other FLTK Widgets as children,
  unless those Widgets are modified to draw using OpenGL calls.
*/
class FL_EXPORT Fl_Gl_Window : public Fl_Window {

  int mode_;
  const int *alist;
  Fl_Gl_Choice *g;
  GLContext context_;
  char valid_f_;
  char damage1_; // damage() of back buffer
  virtual void draw_overlay();
  void init();

  void *overlay;
  void make_overlay();
  friend class _Fl_Gl_Overlay;

  static int can_do(int, const int *);
  int mode(int, const int *);

public:

  void show();
  void show(int a, char **b) {Fl_Window::show(a,b);}
  void flush();
  void hide();
  void resize(int,int,int,int);

  /**
    Is turned off when FLTK creates a new
    context for this window or when the window resizes, and is turned on <I>
    after</I> draw() is called.  You can use this inside your 
    draw() method to avoid unneccessarily initializing the OpenGL
    context.  Just do this:
    \code
    void mywindow::draw() {
     if (!valid()) {
       glViewport(0,0,w(),h());
       glFrustum(...);
       ...other initialization...
     }
     if (!context_valid()) {
       ...load textures, etc. ...
     }
     ... draw your geometry here ...
    }
    \endcode
    
    You can turn valid() on by calling valid(1).  You
    should only do this after fixing the transformation inside a draw()
    or after make_current().  This is done automatically after 
    draw() returns.
  */
  char valid() const {return valid_f_ & 1;}
  /**
    See char Fl_Gl_Window::valid() const 
  */
  void valid(char v) {if (v) valid_f_ |= 1; else valid_f_ &= 0xfe;}
  void invalidate();

  /**
    Will only be set if the 
    OpenGL context is created or recreated. It differs from
    Fl_Gl_Window::valid() which is also set whenever the context
    changes size.
  */
  char context_valid() const {return valid_f_ & 2;}
  /**
    See char Fl_Gl_Window::context_valid() const 
  */
  void context_valid(char v) {if (v) valid_f_ |= 2; else valid_f_ &= 0xfd;}

  static int can_do(int m) {return can_do(m,0);}
  static int can_do(const int *m) {return can_do(0, m);}
  /**
    See static int Fl_Gl_Window::can_do(int) 
  */
  int can_do() {return can_do(mode_,alist);}
  /**
    Set or change the OpenGL capabilites of the window.  The value can be
    any of the following OR'd together:
    <UL>
    <LI>FL_RGB - RGB color (not indexed) </LI>
    <LI>FL_RGB8 - RGB color with at least 8 bits of each color </LI>
    <LI>FL_INDEX - Indexed mode </LI>
    <LI>FL_SINGLE - not double buffered </LI>
    <LI>FL_DOUBLE - double buffered </LI>
    <LI>FL_ACCUM - accumulation buffer </LI>
    <LI>FL_ALPHA - alpha channel in color </LI>
    <LI>FL_DEPTH - depth buffer </LI>
    <LI>FL_STENCIL - stencil buffer </LI>
    <LI>FL_MULTISAMPLE - multisample antialiasing </LI>
    </UL>
    FL_RGB and FL_SINGLE have a value of zero, so they
    are &quot;on&quot; unless you give FL_INDEX or FL_DOUBLE.
    <P>If the desired combination cannot be done, FLTK will try turning off 
    FL_MULTISAMPLE.  If this also fails the show() will call 
    Fl::error() and not show the window. </P>
    <P>You can change the mode while the window is displayed.  This is most
    useful for turning double-buffering on and off.  Under X this will
    cause the old X window to be destroyed and a new one to be created.  If
    this is a top-level window this will unfortunately also cause the
    window to blink, raise to the top, and be de-iconized, and the xid()
    will change, possibly breaking other code.  It is best to make the GL
    window a child of another window if you wish to do this!
  */
  Fl_Mode mode() const {return (Fl_Mode)mode_;}
  int mode(int a) {return mode(a,0);}
  int mode(const int *a) {return mode(0, a);}
  void* context() const {return context_;}
  void context(void*, int destroy_flag = 0);
  void make_current();
  void swap_buffers();
  void ortho();

  /**
    Returns true if the hardware overlay is possible.  If this is false,
    FLTK will try to simulate the overlay, with significant loss of update
    speed.  Calling this will cause FLTK to open the display.
  */
  int can_do_overlay();
  /**
    This method causes draw_overlay to be called at a later time.
    Initially the overlay is clear, if you want the window to display
    something in the overlay when it first appears, you must call this
    immediately after you show() your window.
  */
  void redraw_overlay();
  void hide_overlay();
  /**
    The make_overlay_current() method selects the OpenGL context
    for the widget's overlay.  It is called automatically prior to the 
    draw_overlay() method being called and can also be used to
    implement feedback and/or selection within the handle()
    method.
  */
  void make_overlay_current();

  ~Fl_Gl_Window();
  /**
    Creates a new Fl_Gl_Window widget using the given position,
    size, and label string. The default boxtype is FL_NO_BOX. The
    default mode is FL_RGB|FL_DOUBLE|FL_DEPTH.
  */
  Fl_Gl_Window(int W, int H, const char *l=0) : Fl_Window(W,H,l) {init();}
  Fl_Gl_Window(int X, int Y, int W, int H, const char *l=0)
    : Fl_Window(X,Y,W,H,l) {init();}
};

#endif

//
// End of "$Id$".
//