bionic (3) calc_spline.3alleg4.gz

NAME

       calc_spline - Calculates a series of values along a Bezier spline. Allegro game programming library.

SYNOPSIS

       #include <allegro.h>

       void calc_spline(const int points[8], int npts, int *x, int *y);

DESCRIPTION

       Calculates  a series of npts values along a Bezier spline, storing them in the output x and y arrays. The
       Bezier curve is specified by the four x/y control points in the points  array:  points[0]  and  points[1]
       contain  the  coordinates  of the first control point, points[2] and points[3] are the second point, etc.
       Control points 0 and 3 are the ends of the spline, and points 1 and 2  are  guides.  The  curve  probably
       won't  pass  through  points  1 and 2, but they affect the shape of the curve between points 0 and 3 (the
       lines p0-p1 and p2-p3 are tangents to the spline). The easiest way to think  of  it  is  that  the  curve
       starts  at  p0,  heading  in  the  direction  of  p1,  but curves round so that it arrives at p3 from the
       direction of p2.  In addition to their role as graphics primitives,  spline  curves  can  be  useful  for
       constructing smooth paths around a series of control points, as in exspline.c.

SEE ALSO

       spline(3alleg4), exspline(3alleg4)