/*
 * (c) Copyright 1993, Silicon Graphics, Inc.
 *               1993-1995 Microsoft Corporation
 *
 * ALL RIGHTS RESERVED
 *
 * Please refer to OpenGL/readme.txt for additional information
 *
 */

/*
 *  plane.c
 *  This program demonstrates the use of local versus 
 *  infinite lighting on a flat plane.
 */
#include "glos.h"

#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glaux.h>

void myinit(void);
void drawPlane(void);
void CALLBACK display(void);
void CALLBACK myReshape(GLsizei w, GLsizei h);

/*  Initialize material property, light source, and lighting model.
 */
void myinit(void)
{
    GLfloat mat_ambient[] = { 0.0, 0.0, 0.0, 1.0 };
/*   mat_specular and mat_shininess are NOT default values  */
    GLfloat mat_diffuse[] = { 0.4, 0.4, 0.4, 1.0 };
    GLfloat mat_specular[] = { 1.0, 1.0, 1.0, 1.0 };
    GLfloat mat_shininess[] = { 15.0 };

    GLfloat light_ambient[] = { 0.0, 0.0, 0.0, 1.0 };
    GLfloat light_diffuse[] = { 1.0, 1.0, 1.0, 1.0 };
    GLfloat light_specular[] = { 1.0, 1.0, 1.0, 1.0 };
    GLfloat lmodel_ambient[] = { 0.2, 0.2, 0.2, 1.0 };

    glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient);
    glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);
    glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
    glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);
    glLightfv(GL_LIGHT0, GL_AMBIENT, light_ambient);
    glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse);
    glLightfv(GL_LIGHT0, GL_SPECULAR, light_specular);
    glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);

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

void drawPlane(void)
{
    glBegin (GL_QUADS);
    glNormal3f (0.0, 0.0, 1.0);
    glVertex3f (-1.0, -1.0, 0.0);
    glVertex3f (0.0, -1.0, 0.0);
    glVertex3f (0.0, 0.0, 0.0);
    glVertex3f (-1.0, 0.0, 0.0);

    glNormal3f (0.0, 0.0, 1.0);
    glVertex3f (0.0, -1.0, 0.0);
    glVertex3f (1.0, -1.0, 0.0);
    glVertex3f (1.0, 0.0, 0.0);
    glVertex3f (0.0, 0.0, 0.0);

    glNormal3f (0.0, 0.0, 1.0);
    glVertex3f (0.0, 0.0, 0.0);
    glVertex3f (1.0, 0.0, 0.0);
    glVertex3f (1.0, 1.0, 0.0);
    glVertex3f (0.0, 1.0, 0.0);

    glNormal3f (0.0, 0.0, 1.0);
    glVertex3f (0.0, 0.0, 0.0);
    glVertex3f (0.0, 1.0, 0.0);
    glVertex3f (-1.0, 1.0, 0.0);
    glVertex3f (-1.0, 0.0, 0.0);
    glEnd();
}

void CALLBACK display (void)
{
    GLfloat infinite_light[] = { 1.0, 1.0, 1.0, 0.0 };
    GLfloat local_light[] = { 1.0, 1.0, 1.0, 1.0 };

    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glPushMatrix ();
    glTranslatef (-1.5, 0.0, 0.0);
    glLightfv (GL_LIGHT0, GL_POSITION, infinite_light);
    drawPlane ();
    glPopMatrix ();

    glPushMatrix ();
    glTranslatef (1.5, 0.0, 0.0);
    glLightfv (GL_LIGHT0, GL_POSITION, local_light);
    drawPlane ();
    glPopMatrix ();
    glFlush ();
}

void CALLBACK myReshape (GLsizei w, GLsizei h)
{
    h = (h == 0) ? 1 : h;
    glViewport (0, 0, w, h);
    glMatrixMode (GL_PROJECTION);
    glLoadIdentity ();
    if (w <= h) 
    glOrtho (-1.5, 1.5, -1.5*(GLdouble)h/(GLdouble)w, 
        1.5*(GLdouble)h/(GLdouble)w, -10.0, 10.0);
    else 
    glOrtho (-1.5*(GLdouble)w/(GLdouble)h, 
        1.5*(GLdouble)w/(GLdouble)h, -1.5, 1.5, -10.0, 10.0);
    glMatrixMode (GL_MODELVIEW);
}

/*  Main Loop
 *  Open window with initial window size, title bar, 
 *  RGBA display mode, and handle input events.
 */
int main(int argc, char** argv)
{
    auxInitDisplayMode (AUX_SINGLE | AUX_RGB | AUX_DEPTH16);
    auxInitPosition (0, 0, 500, 200);
    auxInitWindow ("Local vs Infinite Lighting");
    myinit();
    auxReshapeFunc (myReshape);
    auxMainLoop(display);
    return(0);
}