151 lines
4.8 KiB
C#
151 lines
4.8 KiB
C#
#region --- License ---
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/* Licensed under the MIT/X11 license.
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* Copyright (c) 2006-2008 the OpenTK Team.
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* This notice may not be removed from any source distribution.
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* See license.txt for licensing detailed licensing details.
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*
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* Contributions by Georg W<>chter.
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*/
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#endregion
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using System;
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using System.Collections.Generic;
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using System.Text;
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namespace OpenTK
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{
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/// <summary>
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/// Represents a quadric bezier curve with two anchor and one control point.
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/// </summary>
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[Serializable]
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public struct BezierCurveQuadric
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{
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#region Fields
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/// <summary>
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/// Start anchor point.
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/// </summary>
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public Vector2 StartAnchor;
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/// <summary>
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/// End anchor point.
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/// </summary>
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public Vector2 EndAnchor;
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/// <summary>
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/// Control point, controls the direction of both endings of the curve.
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/// </summary>
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public Vector2 ControlPoint;
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/// <summary>
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/// The parallel value.
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/// </summary>
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/// <remarks>This value defines whether the curve should be calculated as a
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/// parallel curve to the original bezier curve. A value of 0.0f represents
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/// the original curve, 5.0f i.e. stands for a curve that has always a distance
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/// of 5.f to the orignal curve at any point.</remarks>
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public float Parallel;
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#endregion
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#region Constructors
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/// <summary>
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/// Constructs a new <see cref="BezierCurveQuadric"/>.
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/// </summary>
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/// <param name="startAnchor">The start anchor.</param>
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/// <param name="endAnchor">The end anchor.</param>
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/// <param name="controlPoint">The control point.</param>
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public BezierCurveQuadric(Vector2 startAnchor, Vector2 endAnchor, Vector2 controlPoint)
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{
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this.StartAnchor = startAnchor;
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this.EndAnchor = endAnchor;
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this.ControlPoint = controlPoint;
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this.Parallel = 0.0f;
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}
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/// <summary>
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/// Constructs a new <see cref="BezierCurveQuadric"/>.
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/// </summary>
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/// <param name="parallel">The parallel value.</param>
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/// <param name="startAnchor">The start anchor.</param>
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/// <param name="endAnchor">The end anchor.</param>
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/// <param name="controlPoint">The control point.</param>
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public BezierCurveQuadric(float parallel, Vector2 startAnchor, Vector2 endAnchor, Vector2 controlPoint)
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{
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this.Parallel = parallel;
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this.StartAnchor = startAnchor;
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this.EndAnchor = endAnchor;
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this.ControlPoint = controlPoint;
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}
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#endregion
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#region Functions
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/// <summary>
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/// Calculates the point with the specified t.
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/// </summary>
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/// <param name="t">The t value, between 0.0f and 1.0f.</param>
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/// <returns>Resulting point.</returns>
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public Vector2 CalculatePoint(float t)
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{
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Vector2 r = new Vector2();
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float c = 1.0f - t;
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r.X = (c * c * StartAnchor.X) + (2 * t * c * ControlPoint.X) + (t * t * EndAnchor.X);
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r.Y = (c * c * StartAnchor.Y) + (2 * t * c * ControlPoint.Y) + (t * t * EndAnchor.Y);
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if (Parallel == 0.0f)
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return r;
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Vector2 perpendicular = new Vector2();
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if (t == 0.0f)
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perpendicular = ControlPoint - StartAnchor;
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else
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perpendicular = r - CalculatePointOfDerivative(t);
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return r + Vector2.Normalize(perpendicular).PerpendicularRight * Parallel;
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}
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/// <summary>
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/// Calculates the point with the specified t of the derivative of this function.
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/// </summary>
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/// <param name="t">The t, value between 0.0f and 1.0f.</param>
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/// <returns>Resulting point.</returns>
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private Vector2 CalculatePointOfDerivative(float t)
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{
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Vector2 r = new Vector2();
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r.X = (1.0f - t) * StartAnchor.X + t * ControlPoint.X;
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r.Y = (1.0f - t) * StartAnchor.Y + t * ControlPoint.Y;
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return r;
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}
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/// <summary>
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/// Calculates the length of this bezier curve.
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/// </summary>
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/// <param name="precision">The precision.</param>
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/// <returns>Length of curve.</returns>
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/// <remarks>The precision gets better when the <paramref name="precision"/>
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/// value gets smaller.</remarks>
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public float CalculateLength(float precision)
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{
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float length = 0.0f;
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Vector2 old = CalculatePoint(0.0f);
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for (float i = precision; i < (1.0f + precision); i += precision)
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{
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Vector2 n = CalculatePoint(i);
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length += (n - old).Length;
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old = n;
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}
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return length;
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}
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#endregion
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}
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}
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