{=============================================================================}
{= Copyright (c) Mark J. Kilgard, 1994.                                      =}
{=============================================================================}

{=============================================================================}
{= (c) Copyright 1993, 1994, Silicon Graphics, Inc.                          =}
{= ALL RIGHTS RESERVED                                                       =}
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{= written prior permission.                                                 =}
{=                                                                           =}
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{=                                                                           =}
{= US Government Users Restricted Rights                                     =}
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{=                                                                           =}
{= OpenGL(TM) is a trademark of Silicon Graphics, Inc.                       =}
{=============================================================================}
unit Scene;

interface

implementation

uses
    MGLTypes,
    MGLGl,
    MGLGlut,
    DemoList,
    CmdLine;

// Initialize material property and light source.
procedure   MyInit;
const
    // light_position is NOT default value
    light_ambient   : array[0..3] of GLfloat = ( 0.0, 0.0, 0.0, 1.0 );
    light_diffuse   : array[0..3] of GLfloat = ( 1.0, 1.0, 1.0, 1.0 );
    light_specular  : array[0..3] of GLfloat = ( 1.0, 1.0, 1.0, 1.0 );
    light_position  : array[0..3] of GLfloat = ( 1.0, 1.0, 1.0, 0.0 );
begin
    glLightfv (GL_LIGHT0, GL_AMBIENT, @light_ambient);
    glLightfv (GL_LIGHT0, GL_DIFFUSE, @light_diffuse);
    glLightfv (GL_LIGHT0, GL_SPECULAR, @light_specular);
    glLightfv (GL_LIGHT0, GL_POSITION, @light_position);

    glEnable (GL_LIGHTING);
    glEnable (GL_LIGHT0);
    glDepthFunc(GL_LESS);
    glEnable(GL_DEPTH_TEST);
end;

procedure   Display; cdecl;
begin
    glClear (GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);

    glPushMatrix ();
    glRotatef (20.0, 1.0, 0.0, 0.0);

    glPushMatrix ();
    glTranslatef (-0.75, 0.5, 0.0);
    glRotatef (90.0, 1.0, 0.0, 0.0);
    glutSolidTorus (0.275, 0.85, 15, 15);
    glPopMatrix ();

    glPushMatrix ();
    glTranslatef (-0.75, -0.5, 0.0);
    glRotatef (270.0, 1.0, 0.0, 0.0);
    glutSolidCone (1.0, 2.0, 15, 15);
    glPopMatrix ();

    glPushMatrix ();
    glTranslatef (0.75, 0.0, -1.0);
    glutSolidSphere (1.0, 15, 15);
    glPopMatrix ();

    glPopMatrix ();
    glFlush ();
end;

procedure   MyReshape(w, h: int); cdecl;
begin
    glViewport (0, 0, w, h);
    glMatrixMode (GL_PROJECTION);
    glLoadIdentity ();
    if w <= h then
        glOrtho (-2.5, 2.5, -2.5*h/w, 2.5*h/w, -10.0, 10.0)
    else
        glOrtho (-2.5*w/h, 2.5*w/h, -2.5, 2.5, -10.0, 10.0);
    glMatrixMode (GL_MODELVIEW);
end;

// Main Loop
// Open window with initial window size, title bar,
// RGBA display mode, and handle input events.
procedure   Demo;
begin
    InitGLUT;
    glutInitDisplayMode (GLUT_SINGLE or GLUT_RGB or GLUT_DEPTH);
    glutInitWindowSize (500, 500);
    glutCreateWindow ('Scene');
    MyInit ();
    glutReshapeFunc (MyReshape);
    glutDisplayFunc(Display);
    glutMainLoop();
end;

initialization
    RegisterDemo(
                 'Book',
                 'Scene',
                 'This program demonstrates the use of the GL lighting model. '+
                 'Objects are drawn using a grey material characteristic. '+
                 'A single light source illuminates the objects.',
                 Demo
                );
end.
