/* Demonstrates the difference between directional and positional lights.
   It uses a sphere, so that we're guaranteed to get specular highlights. 
   
Written by Scott D. Anderson
scott.anderson@acm.org
Fall 2004
*/

#include <stdio.h>
#include <math.h>
#include <tw.h>

void display(void) {
    twDisplayInit();
    twCamera();

    GLfloat light0Pos[] = {0, 0, 1, 0};
    twGrayLight(GL_LIGHT0,light0Pos,1,1,1);

    GLfloat light1Pos[] = {0, 0, 1, 1};
    twGrayLight(GL_LIGHT1,light1Pos,1,1,1);

    glEnable(GL_LIGHTING);
    glShadeModel(GL_SMOOTH);
    twAmbient(0.2);

    twTriple objColor = {0.2, 0.3, 0.4};
    twColor(objColor,0.9,20);        

    glEnable(GL_LIGHT0);
    glDisable(GL_LIGHT1);
    glPushMatrix();
    glTranslatef(-1,0,0);
    glutSolidSphere(1,30,30);        // left ball
    glPopMatrix();

    glEnable(GL_LIGHT1);
    glDisable(GL_LIGHT0);
    glPushMatrix();
    glTranslatef(1,0,0);
    glutSolidSphere(1,30,30);        // right ball
    glPopMatrix();

    glFlush();
    glutSwapBuffers();
}

int main(int argc, char** argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    twInitWindowSize(500,300);
    glutCreateWindow(argv[0]);
    glutDisplayFunc(display);
    const float SIZE = 0.7;
    twBoundingBox(-2*SIZE,+2*SIZE,-SIZE,+SIZE,-SIZE,+SIZE); // a lie, to get us closer
    twMainInit();
    glutMainLoop();
    return 0;
}