fltk/FL/gl.h

//
// OpenGL header file for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2018 by Bill Spitzak and others.
//
// You must include this instead of GL/gl.h to get the Microsoft
// APIENTRY stuff included (from <windows.h>) prior to the OpenGL
// header files.
//
// This file also provides "missing" OpenGL functions, and
// gl_start() and gl_finish() to allow OpenGL to be used in any window
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file.  If this
// file is missing or damaged, see the license at:
//
//     https://www.fltk.org/COPYING.php
//
// Please see the following page on how to report bugs and issues:
//
//     https://www.fltk.org/bugs.php
//

/**
 \file gl.h
 This file defines wrapper functions for OpenGL in FLTK

 To use OpenGL from within an FLTK application you MUST use gl_visual()
 to select the default visual before doing show() on any windows. Mesa
 will crash if you try to use a visual not returned by glxChooseVisual.

 Historically, this did not always work well with Fl_Double_Window's!
 It can try to draw into the front buffer.
 Depending on the system this might either
 crash or do nothing (when pixmaps are being used as back buffer
 and GL is being done by hardware), work correctly (when GL is done
 with software, such as Mesa), or draw into the front buffer and
 be erased when the buffers are swapped (when double buffer hardware
 is being used)
 */

#ifndef FL_gl_H
#  define FL_gl_H

#  include "Enumerations.H" // for color names
#  ifdef _WIN32
#    include <windows.h>
#  endif
#  ifndef APIENTRY
#    if defined(__CYGWIN__)
#      define APIENTRY __attribute__ ((__stdcall__))
#    else
#      define APIENTRY
#    endif
#  endif

#  ifdef __APPLE__ // PORTME: OpenGL path abstraction
#    if !defined(__gl3_h_) // make sure OpenGL/gl3.h was not included before
#      include <OpenGL/gl.h>
#    endif
#  else
#    include <GL/gl.h>
#  endif  // __APPLE__ // PORTME: OpenGL Path abstraction

FL_EXPORT void gl_start();
FL_EXPORT void gl_finish();

FL_EXPORT void gl_color(Fl_Color i);
/** back compatibility */
inline void gl_color(int c) {gl_color((Fl_Color)c);}

FL_EXPORT void gl_rect(int x,int y,int w,int h);
FL_EXPORT void gl_rectf(int x,int y,int w,int h);

FL_EXPORT void gl_font(int fontid, int size);
FL_EXPORT int  gl_height();
FL_EXPORT int  gl_descent();
FL_EXPORT double gl_width(const char *);
FL_EXPORT double gl_width(const char *, int n);
FL_EXPORT double gl_width(uchar);

FL_EXPORT void gl_draw(const char*);
FL_EXPORT void gl_draw(const char*, int n);
FL_EXPORT void gl_draw(const char*, int x, int y);
FL_EXPORT void gl_draw(const char*, float x, float y);
FL_EXPORT void gl_draw(const char*, int n, int x, int y);
FL_EXPORT void gl_draw(const char*, int n, float x, float y);
FL_EXPORT void gl_draw(const char*, int x, int y, int w, int h, Fl_Align);
FL_EXPORT void gl_measure(const char*, int& x, int& y);
FL_EXPORT void gl_texture_pile_height(int max);
FL_EXPORT int  gl_texture_pile_height();
FL_EXPORT void gl_texture_reset();

FL_EXPORT void gl_draw_image(const uchar *, int x,int y,int w,int h, int d=3, int ld=0);

#endif // !FL_gl_H