|
private static CalculatePointOfDerivative ( IList |
||
| points | IList |
The points. |
| t | float | The t parameter, value between 0.0f and 1.0f. |
| Résultat | System.Vector2 | |
private static Vector2 CalculatePointOfDerivative(IList<Vector2> points, float t)
{
Vector2 r = new Vector2();
double c = 1.0d - (double)t;
float temp;
int i = 0;
foreach (Vector2 pt in points)
{
temp = (float)MathHelper.BinomialCoefficient(points.Count - 2, i) * (float)(System.Math.Pow(t, i) *
System.Math.Pow(c, (points.Count - 2) - i));
r.X += temp * pt.X;
r.Y += temp * pt.Y;
i++;
}
return r;
}
/// <summary>
/// Calculates the point on the given bezier curve with the specified t parameter.
/// </summary>
/// <param name="points">The points.</param>
/// <param name="t">The t parameter, a value between 0.0f and 1.0f.</param>
/// <param name="parallel">The parallel value.</param>
/// <returns>Resulting point.</returns>
/// <remarks>The <paramref name="parallel"/> parameter defines whether the curve should be calculated as a
/// parallel curve to the original bezier curve. A value of 0.0f represents
/// the original curve, 5.0f represents a curve that has always a distance
/// of 5.0f to the orignal curve.</remarks>
public static Vector2 CalculatePoint(IList <Vector2> points, float t, float parallel)
{
Vector2 r = new Vector2();
double c = 1.0d - (double)t;
float temp;
int i = 0;
foreach (Vector2 pt in points)
{
temp = (float)MathHelper.BinomialCoefficient(points.Count - 1, i) * (float)(System.Math.Pow(t, i) *
System.Math.Pow(c, (points.Count - 1) - i));
r.X += temp * pt.X;
r.Y += temp * pt.Y;
i++;
}
if (parallel == 0.0f)
{
return(r);
}
Vector2 perpendicular = new Vector2();
if (t != 0.0f)
{
perpendicular = r - BezierCurve.CalculatePointOfDerivative(points, t);
}
else
{
perpendicular = points[1] - points[0];
}
return(r + Vector2.Normalize(perpendicular).PerpendicularRight *parallel);
}
