/*
 * hw02.c: 
 *   
 *  For a cube specified in three-space by the coordinates of its vertices,
 *  perform two rotations and one tanslation.  Then project the cube into
 *  the image plane.
 *
 * 2/15/2002 jph
 *
 */

#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <string.h>

/*
 * Type for a point in upright pinhole camera model (NOTES p. 1.17)
 */
struct point {
  float     X;        /* X-coordinate in the real world */
  float     Y;        /* Y-coordinate in the real world */
  float     Z;        /* Z-coordinate in the real world */
  float     x;        /* x-coordinate in the image plane */
  float     y;        /* y-coordinate in the image plane */
};
typedef struct point point;
typedef point *Ppoint;


/*----------------------------------------------------------------------*/
/*   MAIN                                                               */
/*----------------------------------------------------------------------*/

main(argc,argv) 

  int     argc;
  char   *argv[];
{

  int      i;                     /* loop counter */
  point    P[8];                  /* array of cube corners */
  float    f;                     /* camera focal length in meters */
  double   Theta;                 /* rotation angle */
  double   Xold;                  /* old X coordinate of a point */
  double   Yold;                  /* old Y coordinate of a point */
  double   Zold;                  /* old Z coordinate of a point */

 /*
  * Initialize the world coordinates of the eight cube corners
  */
  P[0].X = 0.00; P[0].Y = 0.00; P[0].Z = 0.00;
  P[1].X = 0.00; P[1].Y = 0.00; P[1].Z = 0.05;
  P[2].X = 0.05; P[2].Y = 0.00; P[2].Z = 0.05;
  P[3].X = 0.05; P[3].Y = 0.00; P[3].Z = 0.00;
  P[4].X = 0.00; P[4].Y = 0.05; P[4].Z = 0.00;
  P[5].X = 0.00; P[5].Y = 0.05; P[5].Z = 0.05;
  P[6].X = 0.05; P[6].Y = 0.05; P[6].Z = 0.05;
  P[7].X = 0.05; P[7].Y = 0.05; P[7].Z = 0.00;

 /*
  * First rotation - update X & Z coordinates of all eight points
  */
  Theta = (double)30.0 * (double)2.0 * M_PI / (double)360.0;
  for (i=0; i < 8; i++) {
    Zold = (double)P[i].Z;
    Xold = (double)P[i].X;
    P[i].Z = (float)(cos(Theta)*Zold - sin(Theta)*Xold);
    P[i].X = (float)(sin(Theta)*Zold + cos(Theta)*Xold);
  }

 /*
  * Second rotation - update Y & Z coordinates of all eight points
  */
  Theta = (double)-20.0 * (double)2.0 * M_PI / (double)360.0;
  for (i=0; i < 8; i++) {
    Yold = (double)P[i].Y;
    Zold = (double)P[i].Z;
    P[i].Y = (float)(cos(Theta)*Yold - sin(Theta)*Zold);
    P[i].Z = (float)(sin(Theta)*Yold + cos(Theta)*Zold);
  }

 /*
  * Translation:  update Z coordinates of all eight points
  */
  for (i=0; i < 8; i++) {
    P[i].Z += (float)1.0;
  }

 /*
  * Project all eight points into the image plane
  */
  f = (float)0.05;
  for (i=0; i < 8; i++) {
    if (P[i].Z == (float)0.0) {
      printf("\nError: point %d has Z=0.0\n\n",i);
      exit(-1);
    } else {
      P[i].x = f/P[i].Z * P[i].X;
      P[i].y = f/P[i].Z * P[i].Y;
    }
  }

 /*
  * Report
  */
  printf("\n\n");
  for (i=0; i < 8; i++) {
    printf("P%d: x=%9.5f         y=%9.5f\n",i+1,P[i].x,P[i].y);
  }
  printf("\n\n");
  return;
} /*----------------  Main  ----------------------------------------------*/