www.pudn.com > CG2Programs.rar > transformObject3.c

/* transformObject3, Chapter 11, pp. 423-425 */

/* EXAMPLE STARTS HERE */
#include 
#include "graphics.h"

#define PI 3.14159

typedef float Matrix4x4[4][4];

Matrix4x4 theMatrix;

void matrix4x4SetIdentity (Matrix4x4 m)
{
  int r,c;

  for (r=0; r<4; r++) 
    for (c=0; c<4; c++)
      m[r][c] = (r == c);
}

/* Multiplies matrix a times b, putting result in b */
void matrix4x4PreMultiply (Matrix4x4 a, Matrix4x4 b)
{
  int r,c;
  Matrix4x4 tmp;

  for (r=0; r<4; r++)
    for (c=0; c<4; c++)
      tmp[r][c] = a[r][0]*b[0][c] + a[r][1]*b[1][c] +
	a[r][2]*b[2][c] + a[r][3]*b[3][c];
  for (r=0; r<4; r++)
    for (c=0; c<4; c++)
      b[r][c] = tmp[r][c];
}

void translate3 (float tx, float ty, float tz)
{
  Matrix4x4 m;

  matrix4x4SetIdentity (m);
  m[0][3] = tx; m[1][3] = ty; m[2][3] = tz; 
  matrix4x4PreMultiply (m, theMatrix);
}

void scale3 (float sx, float sy, float sz, wcPt3 center)
{
  Matrix4x4 m;

  matrix4x4SetIdentity (m);
  m[0][0] = sx;
  m[0][3] = (1 - sx) * center.x;
  m[1][1] = sy;
  m[1][3] = (1 - sy) * center.y;
  m[2][2] = sz;
  m[2][3] = (1 - sz) * center.z;
  matrix4x4PreMultiply (m, theMatrix);
}

void rotate3 (wcPt3 p1, wcPt3 p2, float radianAngle)
{
  float length = sqrt ((p2.x - p1.x) * (p2.x - p1.x) +
		       (p2.y - p1.y) * (p2.y - p1.y) +
		       (p2.z - p1.z) * (p2.z - p1.z));
  float cosA2 = cosf (radianAngle / 2.0);
  float sinA2 = sinf (radianAngle / 2.0);
  float a = sinA2 * (p2.x - p1.x) / length;
  float b = sinA2 * (p2.y - p1.y) / length;
  float c = sinA2 * (p2.z - p1.z) / length;
  Matrix4x4 m;

  translate3 (-p1.x, -p1.y, -p1.z);
  matrix4x4SetIdentity (m);
  m[0][0] = 1.0 - 2*b*b - 2*c*c;
  m[0][1] = 2*a*b - 2*cosA2*c;
  m[0][2] = 2*a*c + 2*cosA2*b;
  m[1][0] = 2*a*b + 2*cosA2*c;
  m[1][1] = 1.0 - 2*a*a - 2*c*c;
  m[1][2] = 2*b*c - 2*cosA2*a;
  m[2][0] = 2*a*c - 2*cosA2*b;
  m[2][1] = 2*b*c + 2*cosA2*a;
  m[2][2] = 1.0 - 2*a*a - 2*b*b;
  matrix4x4PreMultiply (m, theMatrix);
  translate3 (p1.x, p1.y, p1.z);
}

void transformPoints3 (int nPts, wcPt3 * pts)
{
  int k, j;
  float tmp[3];

  for (k=0; k