Some Catmull-Rom code scraped from the web

gistfile1.c

void PointOnCurve(TrackPoint &out, float t, TrackPoint p0, TrackPoint p1, TrackPoint p2, TrackPoint p3)
{
  float t2 = t * t;
  float t3 = t2 * t;
  float tension = 0.5f;

  out.x = 0.5f * ( ( 2.0f * p1.x ) +
    ( -p0.x + p2.x ) * t +
    ( 2.0f * p0.x - 5.0f * p1.x + 4 * p2.x - p3.x ) * t2 +
    ( -p0.x + 3.0f * p1.x - 3.0f * p2.x + p3.x ) * t3 );

  out.y = 0.5f * ( ( 2.0f * p1.y ) +
    ( -p0.y + p2.y ) * t +
    ( 2.0f * p0.y - 5.0f * p1.y + 4 * p2.y - p3.y ) * t2 +
    ( -p0.y + 3.0f * p1.y - 3.0f * p2.y + p3.y ) * t3 );
}