/// <summary>
/// Gets the arc length of the arc in the interval [t0, t1].
/// </summary>
/// <remarks>
/// This function calculates an integration for the first and the last curve pieces of the arc.
/// Then adds the precalculated arc lengths for the curves in the middle.
/// </remarks>
/// <param name="t0">The start parameter in [0, 1].</param>
/// <param name="t1">The end parameter in [0, 1].</param>
/// <returns>The arc length.</returns>
public float GetArcLength(float t0, float t1)
{
_UpdateLengths();
if (t0 == t1)
{
return(0);
}
if (t0 > t1)
{
float tmp = t0;
t0 = t1;
t1 = tmp;
}
int curve0 = (int)(t0 * curveCount);
int curve1 = t1 == 1 ? curveCount - 1 : (int)(t1 * curveCount);
t0 = t0 * curveCount - curve0;
t1 = t1 * curveCount - curve1;
curve0 *= 3;
curve1 *= 3;
if (curve0 == curve1)
{
return(Bezier.Integrate(_points[curve0], _points[curve0 + 1], _points[curve0 + 2], _points[curve0 + 3], t0, t1));
}
else
{
float result = 0;
result += Bezier.Integrate(_points[curve0], _points[curve0 + 1], _points[curve0 + 2], _points[curve0 + 3], t0, 1);
for (int i = curve0 / 3 + 1; i < curve1 / 3; i++)
{
result += _curveLengths[i];
}
result += Bezier.Integrate(_points[curve1], _points[curve1 + 1], _points[curve1 + 2], _points[curve1 + 3], 0, t1);
return(result);
}
}
/// <summary>
/// Gets the length of the get curve.
/// </summary>
/// <param name="curveIndex">The curve index.</param>
/// <returns>The curve length.</returns>
private float _GetCurveLength(int curveIndex)
{
int i = curveIndex * 3;
return(Bezier.Integrate(_points[i], _points[i + 1], _points[i + 2], _points[i + 3], 0, 1));
}