/* Demonstrates the projection concepts of distortion, letterboxing, and
   clipping.  Displays two TeddyBears in a 2x1x1 bounding box, and
   defines keyboard callbacks to switch among distortion, letterboxing and
   clipping.
   
Written by Caroline Geiersbach and Scott D. Anderson
scott.anderson@acm.org
Summer 2003
*/

#include <stdio.h>
#include <stdlib.h>		//  for exit and atoi
#include <math.h>
#include <GL/glut.h>
#include <tw.h>

GLfloat pos[] = {16, 16, 16, 1};

// This is the proper display function
void display1(void) {
  glClearColor(0.8,0.8,0.8,1);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  twCamera();			// step 1 camera
  twGrayLight(GL_LIGHT0, pos, 0.2, 1, 1); // step 2 lights

  // step 3 objects
  twTeddyBear();

  glFlush();
  glutSwapBuffers();
}

// This one does the camera last
void display2(void) {
  glClearColor(0.8,0.8,0.8,1);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  twGrayLight(GL_LIGHT0, pos, 0.2, 1, 1); // step 2 lights

  twTeddyBear();		// step 3 objects

  twCamera();			// step 1 camera
  glFlush();
  glutSwapBuffers();
}

// This one does the lights after the objects
void display3(void) {
  glClearColor(0.8,0.8,0.8,1);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  twCamera();			// step 1 camera

  twTeddyBear();		// step 3 objects

  twGrayLight(GL_LIGHT0, pos, 0.2, 1, 1); // step 2 lights

  glFlush();
  glutSwapBuffers();
}

int main(int argc, char** argv) {
    int option;
    
    if( argc < 2 ) {
	printf("Usage: %s {1,2,3}\n1 for Normal Order (Camera, Lights, Objects)\n2 for Camera Last\n3 for Lights Last\n",argv[0]);
	exit(0);
    } else {
	option = atoi(argv[1]);
	printf("option = %d\n",option);
    }
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    twInitWindowSize(500,500);
    glutCreateWindow(argv[0]);
    twBoundingBox(-0.3,0.3,-0.4,0.4,-0.15,0.15);
    switch(option) {
    case 1: glutDisplayFunc(display1); break;
    case 2: glutDisplayFunc(display2); break;
    case 3: glutDisplayFunc(display3); break;
    }
    twMainInit();
    glutMainLoop();
    return 0;
}