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

/*  bezier, Chapter 10, p. 329  */

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

void computeCoefficients (int n, int * c)
{
  int k, i;

  for (k=0; k<=n; k++) {
    /* Compute n!/(k!(n-k)!) */
    c[k] = 1;
    for (i=n; i>=k+1; i--)
      c[k] *= i;
    for (i=n-k; i>=2; i--)
      c[k] /= i;
  }
}

void computePoint
  (float u, wcPt3 * pt, int nControls, wcPt3 * controls, int * c)
{
  int k, n = nControls - 1;
  float blend;

  pt->x = 0.0; pt->y = 0.0; pt->z = 0.0;

  /* Add in influence of each control point */
  for (k=0; kx += controls[k].x * blend;
    pt->y += controls[k].y * blend;
    pt->z += controls[k].z * blend;
  }
}

void bezier (wcPt3 * controls, int nControls, int m, wcPt3 * curve)
{
  /* Allocate space for the coefficients */
  int * c = (int *) malloc (nControls * sizeof (int));
  int i;

  computeCoefficients (nControls-1, c);
  for (i=0; i<=m; i++) 
    computePoint (i / (float) m, &curve[i], nControls, controls, c);
  free (c);
}
/* EXAMPLE ENDS HERE */

#define N_CONTROLS 4
#define N_PTS      128  

void main (int argc, char ** argv)
{
  wcPt3 pts[] = { 50, 50, 0, 150, 150, 0, 250, 40, 0, 300, 200, 0 };
  wcPt3 curvePts[N_PTS+1];
  int i;
  long windowID = openGraphics (*argv, 350, 250);
  float pt[3];

  setBackground (WHITE);
  setColor (BLACK);

  bezier (pts, N_CONTROLS, N_PTS, curvePts);

  /* Use 'gl' to draw the lines */
  bgnline ();
  for (i=0; i