{
  $Id$

  Translation of the Mesa GL headers for FreePascal
  Copyright (C) 1999 Sebastian Guenther


  Mesa 3-D graphics library
  Version:  3.0
  Copyright (C) 1995-1998  Brian Paul

  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., 675 Mass Ave, Cambridge, MA 02139, USA.
}

{$MODE delphi}  // objfpc would not work because of direct proc var assignments

{You have to enable Macros (compiler switch "-Sm") for compiling this unit!
 This is necessary for supporting different platforms with different calling
 conventions via a single unit.}

unit GL;

interface

{$DEFINE GL1_0}
{$DEFINE GL1_1}
{$DEFINE GL1_2}
{$DEFINE MESA}                 {enable if you want to use some special mesa extensions}
{$DEFINE EXTENSIONS}           {enable if you need one/all of extensions}
{$DEFINE SGI_EXTENSIONS}       {enable if you need one/all of extensions}

{$MACRO ON}

{$IFDEF Linux}
  {$LINKLIB c}
{$ELSE}
  {$MESSAGE Unsupported platform.}
{$ENDIF}


// =======================================================
//   Unit specific extensions
// =======================================================

function InitGLFromLibrary(libname: PChar): Boolean;

// determines automatically which libraries to use:
function InitGL: Boolean;


var
  GLDumpUnresolvedFunctions,
  GLInitialized: Boolean;


// =======================================================
//   GL consts, types and functions
// =======================================================


// -------------------------------------------------------
//   GL types
// -------------------------------------------------------

type
  PSingle   = ^Single;
  PDouble   = ^Double;

  GLvoid    = Pointer;
  GLboolean = Byte;

  GLbyte    = ShortInt; // 1-byte signed
  GLshort   = Integer;  // 2-byte signed
  GLint     = LongInt;  // 4-byte signed

  GLubyte   = Byte;     // 1-byte unsigned
  GLushort  = Word;     // 2-byte unsigned
  GLuint    = DWord;    // 4-byte signed

  GLsizei   = LongInt;  // 4-byte signed

  GLfloat   = Single;   // single precision float
  GLclampf  = Single;   // single precision float in [0,1]
  GLdouble  = Double;   // double precision float
  GLclampd  = Double;   // double precision float in [0,1]

  GLenum    = DWord;

  PGLBoolean = ^GLBoolean;
  PGLFloat   = ^GLfloat;
  PGLDouble  = ^GLDouble;

type
  GLbitfield = DWord;  { was an enum - no corresponding thing in pascal }
const
  GL_CURRENT_BIT        = $00000001;
  GL_POINT_BIT          = $00000002;
  GL_LINE_BIT           = $00000004;
  GL_POLYGON_BIT        = $00000008;
  GL_POLYGON_STIPPLE_BIT= $00000010;
  GL_PIXEL_MODE_BIT     = $00000020;
  GL_LIGHTING_BIT       = $00000040;
  GL_FOG_BIT            = $00000080;
  GL_DEPTH_BUFFER_BIT   = $00000100;
  GL_ACCUM_BUFFER_BIT   = $00000200;
  GL_STENCIL_BUFFER_BIT = $00000400;
  GL_VIEWPORT_BIT       = $00000800;
  GL_TRANSFORM_BIT      = $00001000;
  GL_ENABLE_BIT         = $00002000;
  GL_COLOR_BUFFER_BIT   = $00004000;
  GL_HINT_BIT           = $00008000;
  GL_EVAL_BIT           = $00010000;
  GL_LIST_BIT           = $00020000;
  GL_TEXTURE_BIT        = $00040000;
  GL_SCISSOR_BIT        = $00080000;
  GL_ALL_ATTRIB_BITS    = $000fffff;


// -------------------------------------------------------
//   GL constants
// -------------------------------------------------------

{$IFDEF GL1_0}
%GLDeclsIF10
{$ENDIF GL1_0}

{$IFDEF GL1_1}
%GLDeclsIF11
{$ENDIF GL1_1}

{$IFDEF GL1_2}
%GLDeclsIF12
{$ENDIF GL1_2}

const
  // Utility
  GL_VENDOR                             = $1F00;
  GL_RENDERER                           = $1F01;
  GL_VERSION                            = $1F02;
  GL_EXTENSIONS                         = $1F03;

  // Errors
  GL_INVALID_VALUE                      = $0501;
  GL_INVALID_ENUM                       = $0500;
  GL_INVALID_OPERATION                  = $0502;
  GL_STACK_OVERFLOW                     = $0503;
  GL_STACK_UNDERFLOW                    = $0504;
  GL_OUT_OF_MEMORY                      = $0505;


// -------------------------------------------------------
//   GL extensions constants
// -------------------------------------------------------

{$IFDEF EXTENSIONS}
%GLDeclsIF10Ext
{$ENDIF EXTENSIONS}

{$IFDEF SGI_EXTENSIONS}
%GLDeclsIF10SGI
{$ENDIF SGI_EXTENSIONS}

{$IFDEF MESA}
%GLDeclsIF10Mesa
{$ENDIF MESA}


// -------------------------------------------------------
//   GL procedures and functions
// -------------------------------------------------------

{$IFDEF GL1_0}
var
%GLProcsPD10
{$ENDIF GL1_0}

{$IFDEF GL1_1}
var
%GLProcsPD11
{$ENDIF GL1_1}

{$IFDEF GL1_2}
var
%GLProcsPD12
{$ENDIF GL1_2}


// -------------------------------------------------------
//   GL Extensions
// -------------------------------------------------------

{$IFDEF EXTENSIONS}
var
%GLProcsPD10Ext
{$ENDIF EXTENSIONS}

// library dependent extensions

{$IFDEF SGI_EXTENSIONS}
var
%GLProcsPD10SGI
{$ENDIF SGI_EXTENSIONS}

{$ifdef MESA}
var
%GLProcsPD10Mesa
{$endif MESA}


// =======================================================
// =======================================================

implementation


{$LINKLIB m}

function dlopen(AFile: PChar; mode: LongInt): Pointer; external 'dl';
function dlclose(handle: Pointer): LongInt; external 'dl';
function dlsym(handle: Pointer; name: PChar): Pointer; external 'dl';

function LoadLibrary(name: PChar): Pointer;
begin
  Result := dlopen(name, $101 {RTLD_GLOBAL or RTLD_LAZY});
end;

function GetProc(handle: Pointer; name: PChar): Pointer;
begin
  Result := dlsym(handle, name);
  if (Result = nil) and  GLDumpUnresolvedFunctions then
    WriteLn('Unresolved: ', name);
end;

var
  libGL : Pointer;

function InitGLFromLibrary(libname: PChar): Boolean;
begin
  Result := False;
  libGL := LoadLibrary(libname);
  if not Assigned(libGL) then exit;

{$ifdef GL1_0}
%GLProcsPL10
{$endif GL1_0}

{$ifdef GL1_1}
%GLProcsPL11
{$endif GL1_1}

{$ifdef GL1_2}
%GLProcsPL12
{$endif GL1_2}

{$ifdef EXTENSIONS}
%GLProcsPL10Ext
{$endif EXTENSIONS}

{$ifdef SGI_EXTENSIONS}
%GLProcsPL10SGI
{$endif SGI_EXTENSIONS}

{$ifdef MESA}
%GLProcsPL10Mesa
{$endif MESA}

  GLInitialized := True;
  Result := True;
end;

function InitGL: Boolean;
begin
  Result := InitGLFromLibrary('libGL.so') or
            InitGLFromLibrary('libGL.so.1') or
            InitGLFromLibrary('libMesaGL.so') or
            InitGLFromLibrary('libMesaGL.so.3');
end;

initialization
  InitGL;
finalization
  if Assigned(libGL)  then dlclose(libGL);
end.
{
  $Log$
  Revision 1.1  2000-09-03 21:25:45  peter
    * new updated version
    * gtkglarea unit and demo
    * win32 opengl headers
    * morph3d demo

  Revision 1.1  2000/07/13 06:34:17  michael
  + Initial import

  Revision 1.2  2000/05/31 00:34:28  alex
  made templates work

}