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#region --- License ---
/* Licensed under the MIT/X11 license.
* Copyright (c) 2006-2008 the OpenTK Team.
* This notice may not be removed from any source distribution.
* See license.txt for licensing detailed licensing details.
*
* Contributions by Georg W�chter.
*/
#endregion
using System;
using System.Collections.Generic;
using System.Text;
namespace OpenTK.Math
{
/// <summary>
/// Represents a quadric bezier curve with two anchor and one control point.
/// </summary>
[Obsolete("OpenTK.Math functions have been moved to the root OpenTK namespace (reason: XNA compatibility")]
[Serializable]
public struct BezierCurveQuadric
{
#region Fields
/// <summary>
/// Start anchor point.
/// </summary>
public Vector2 StartAnchor;
/// <summary>
/// End anchor point.
/// </summary>
public Vector2 EndAnchor;
/// <summary>
/// Control point, controls the direction of both endings of the curve.
/// </summary>
public Vector2 ControlPoint;
/// <summary>
/// The parallel value.
/// </summary>
/// <remarks>This value 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 i.e. stands for a curve that has always a distance
/// of 5.f to the orignal curve at any point.</remarks>
public float Parallel;
#endregion
#region Constructors
/// <summary>
/// Constructs a new <see cref="BezierCurveQuadric"/>.
/// </summary>
/// <param name="startAnchor">The start anchor.</param>
/// <param name="endAnchor">The end anchor.</param>
/// <param name="controlPoint">The control point.</param>
public BezierCurveQuadric(Vector2 startAnchor, Vector2 endAnchor, Vector2 controlPoint)
{
this.StartAnchor = startAnchor;
this.EndAnchor = endAnchor;
this.ControlPoint = controlPoint;
this.Parallel = 0.0f;
}
/// <summary>
/// Constructs a new <see cref="BezierCurveQuadric"/>.
/// </summary>
/// <param name="parallel">The parallel value.</param>
/// <param name="startAnchor">The start anchor.</param>
/// <param name="endAnchor">The end anchor.</param>
/// <param name="controlPoint">The control point.</param>
public BezierCurveQuadric(float parallel, Vector2 startAnchor, Vector2 endAnchor, Vector2 controlPoint)
{
this.Parallel = parallel;
this.StartAnchor = startAnchor;
this.EndAnchor = endAnchor;
this.ControlPoint = controlPoint;
}
#endregion
#region Functions
/// <summary>
/// Calculates the point with the specified t.
/// </summary>
/// <param name="t">The t value, between 0.0f and 1.0f.</param>
/// <returns>Resulting point.</returns>
public Vector2 CalculatePoint(float t)
{
Vector2 r = new Vector2();
float c = 1.0f - t;
r.X = (c * c * StartAnchor.X) + (2 * t * c * ControlPoint.X) + (t * t * EndAnchor.X);
r.Y = (c * c * StartAnchor.Y) + (2 * t * c * ControlPoint.Y) + (t * t * EndAnchor.Y);
if (Parallel == 0.0f)
return r;
Vector2 perpendicular = new Vector2();
if (t == 0.0f)
perpendicular = ControlPoint - StartAnchor;
else
perpendicular = r - CalculatePointOfDerivative(t);
return r + Vector2.Normalize(perpendicular).PerpendicularRight * Parallel;
}
/// <summary>
/// Calculates the point with the specified t of the derivative of this function.
/// </summary>
/// <param name="t">The t, value between 0.0f and 1.0f.</param>
/// <returns>Resulting point.</returns>
private Vector2 CalculatePointOfDerivative(float t)
{
Vector2 r = new Vector2();
r.X = (1.0f - t) * StartAnchor.X + t * ControlPoint.X;
r.Y = (1.0f - t) * StartAnchor.Y + t * ControlPoint.Y;
return r;
}
/// <summary>
/// Calculates the length of this bezier curve.
/// </summary>
/// <param name="precision">The precision.</param>
/// <returns>Length of curve.</returns>
/// <remarks>The precision gets better when the <paramref name="precision"/>
/// value gets smaller.</remarks>
public float CalculateLength(float precision)
{
float length = 0.0f;
Vector2 old = CalculatePoint(0.0f);
for (float i = precision; i < (1.0f + precision); i += precision)
{
Vector2 n = CalculatePoint(i);
length += (n - old).Length;
old = n;
}
return length;
}
#endregion
}
}
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