A 2d line segment (stripped to only include used methods).
Esempio n. 1
0
        /// <summary>
        /// Enumerates the times and places, if any, where a moving line crosses a point during a time step.
        /// The line's endpoints move at a constant rate along their linear paths.
        /// </summary>
        public static IEnumerable<Sweep> WhenLineSweepsPoint(LineSegment pathOfLineStartPoint,
            LineSegment pathOfLineEndPoint,
            Point point)
        {
            var a = point - pathOfLineStartPoint.Start;
            var b = -pathOfLineStartPoint.Delta;
            var c = pathOfLineEndPoint.Start - pathOfLineStartPoint.Start;
            var d = pathOfLineEndPoint.Delta - pathOfLineStartPoint.Delta;

            return from t in QuadraticRoots(b.Cross(d), a.Cross(d) + b.Cross(c), a.Cross(c))
                   where t >= 0 && t <= 1
                   let start = pathOfLineStartPoint.LerpAcross(t)
                   let end = pathOfLineEndPoint.LerpAcross(t)
                   let s = point.LerpProjectOnto(new LineSegment(start, end))
                   where s >= 0 && s <= 1
                   orderby t
                   select new Sweep(timeProportion: t, acrossProportion: s);
        }
Esempio n. 2
0
 ///<summary>
 ///The proportion that, when lerped across the given line, results in the given point.
 ///If the point is not on the line segment, the result is the closest point on the extended line.
 ///</summary>
 public static double LerpProjectOnto(this Point point, LineSegment line)
 {
     var b = point - line.Start;
     var d = line.Delta;
     return (b * d) / (d * d);
 }