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public LerpAcross ( double proportion ) : |
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| proportion | double | |
| return | ||
/// <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);
}
/// <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));
}
