/* Demonstrates the difference between diffuse and specular lighting.  The
   left ball only gets specular light, the right ball only gets diffuse
   light.  Neither has any ambient light.  
   
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, 1};
    twGrayLight(GL_LIGHT0,light0Pos,1,0,1);

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

    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 gets specular light (light0)
    glPopMatrix();

    glEnable(GL_LIGHT1);
    glDisable(GL_LIGHT0);
    glPushMatrix();
    glTranslatef(1,0,0);
    glutSolidSphere(1,30,30);        // right ball gets diffuse light (light1)
    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);
    twBoundingBox(-1,1,-0.7,0.7,-0.7,0.7); // a lie, to get us closer in
    twMainInit();
    glutMainLoop();
    return 0;
}