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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,127 @@ | ||
| using System; | ||
| using System.Collections.Generic; | ||
| using System.Linq; | ||
| using System.Text; | ||
| using OpenTK; | ||
|
|
||
| namespace JollyBit.Canvas.Shapes | ||
| { | ||
| /// <summary> | ||
| /// A static class with methods for createing bezier curves. Consult http://www.caffeineowl.com/graphics/2d/vectorial/bezierintro.html for a good bezier curves reference. | ||
| /// </summary> | ||
| public static class BezierCurvesHelper | ||
| { | ||
| #region Utility Functions | ||
| /// <summary> | ||
| /// Calculates the minimum distance between a line and a point. | ||
| /// </summary> | ||
| /// <param name="lineStart">The point at which the line starts</param> | ||
| /// <param name="lineEnd">The point at which the line ends</param> | ||
| /// <param name="point">The point</param> | ||
| /// <param name="whatSideOfLine">A negative number if point is on right side of line else returns a positive number. Return zero if the point is on the line. | ||
| /// The same value as CalcWhatSideOfLinePointIsOn would return.</param> | ||
| /// <returns></returns> | ||
| public static float CalcSquaredDistanceBetweenLineAndPoint(ref Vector2 lineStart, ref Vector2 lineEnd, ref Vector2 point, out float whatSideOfLine) | ||
| { | ||
| //http://softsurfer.com/Archive/algorithm_0102/algorithm_0102.htm | ||
| whatSideOfLine = CalcWhatSideOfLinePointIsOn(lineStart, lineEnd, point); | ||
| Vector2 lineDiff; | ||
| Vector2.Subtract(ref lineEnd, ref lineStart, out lineDiff); | ||
| return (whatSideOfLine * whatSideOfLine) / lineDiff.LengthSquared; | ||
| } | ||
|
|
||
| /// <summary> | ||
| /// Calculates the minimum distance between a line and a point. | ||
| /// </summary> | ||
| /// <param name="lineStart">The point at which the line starts</param> | ||
| /// <param name="lineEnd">The point at which the line ends</param> | ||
| /// <param name="point">The point</param> | ||
| public static float CalcSquaredDistanceBetweenLineAndPoint(ref Vector2 lineStart, ref Vector2 lineEnd, ref Vector2 point) | ||
| { | ||
| float whatSideOfLine; | ||
| return CalcSquaredDistanceBetweenLineAndPoint(ref lineStart, ref lineEnd, ref point, out whatSideOfLine); | ||
| } | ||
|
|
||
| /// <summary> | ||
| /// Returns a negative number if point is on right side of line else returns a positive number. Return zero if the point is on the line. | ||
| /// </summary> | ||
| public static float CalcWhatSideOfLinePointIsOn(Vector2 lineStart, Vector2 lineEnd, Vector2 point) | ||
| { | ||
| return (lineEnd.X - lineStart.X) * (point.Y - lineStart.Y) - (lineEnd.Y - lineStart.Y) * (point.X - lineStart.X); | ||
| } | ||
|
|
||
| #endregion | ||
|
|
||
| #region QuadraticBezierCurve | ||
| public static IEnumerable<Vector2> CreateQuadraticBezierCurve(Vector2 anchorPoint1, Vector2 anchorPoint2, Vector2 controlPoint, float flatness) | ||
| { | ||
| flatness = flatness * flatness; | ||
| yield return anchorPoint1; | ||
| foreach (var item in _createQuadraticBezierCurve(anchorPoint1, anchorPoint2, controlPoint, flatness)) yield return item; | ||
| yield return anchorPoint2; | ||
| } | ||
| private static IEnumerable<Vector2> _createQuadraticBezierCurve(Vector2 anchorPoint1, Vector2 anchorPoint2, Vector2 controlPoint, float flatnessSquared) | ||
| { | ||
| //1) Check if flat enough | ||
| if (CalcSquaredDistanceBetweenLineAndPoint(ref anchorPoint1, ref anchorPoint2, ref controlPoint) > flatnessSquared) | ||
| { | ||
| //2) Compute nessary values | ||
| //segControl1 = (a1+c)/2 | ||
| Vector2 segControl1; | ||
| Vector2.Add(ref anchorPoint1, ref controlPoint, out segControl1); | ||
| Vector2.Divide(ref segControl1, 2f, out segControl1); | ||
| //segControl2 = (a1+c)/2 | ||
| Vector2 segControl2; | ||
| Vector2.Add(ref anchorPoint2, ref controlPoint, out segControl2); | ||
| Vector2.Divide(ref segControl2, 2f, out segControl2); | ||
| //segAnchor = (segControl1 + segControl2)/2 = (2c+a1+a2)/4 | ||
| Vector2 segAnchor; | ||
| Vector2.Add(ref segControl1, ref segControl2, out segAnchor); | ||
| Vector2.Divide(ref segAnchor, 2f, out segAnchor); | ||
|
|
||
| //3) Recurse segments | ||
| foreach (var item in _createQuadraticBezierCurve(anchorPoint1, segAnchor, segControl1, flatnessSquared)) yield return item; | ||
| yield return segAnchor; | ||
| foreach (var item in _createQuadraticBezierCurve(segAnchor, anchorPoint2, segControl2, flatnessSquared)) yield return item; | ||
| } | ||
| } | ||
| #endregion | ||
|
|
||
| #region CubicBezierCurve | ||
| //public static IEnumerable<Vector2> CreateCubicBezierCurve(Vector2 anchorPoint1, Vector2 anchorPoint2, Vector2 controlPoint1, Vector2 controlPoint2, float flatness) | ||
| //{ | ||
| // flatness = flatness * flatness; | ||
| // yield return anchorPoint1; | ||
| // foreach (var item in _createCubicBezierCurve(anchorPoint1, anchorPoint2, controlPoint1, controlPoint2, flatness)) yield return item; | ||
| // yield return anchorPoint2; | ||
| //} | ||
| //private static IEnumerable<Vector2> _createCubicBezierCurve(Vector2 anchorPoint1, Vector2 anchorPoint2, Vector2 controlPoint1, Vector2 controlPoint2, float flatnessSquared) | ||
| //{ | ||
| // //1) Check if flat enough | ||
| // //if (CalcSquaredDistanceBetweenLineAndPoint(ref anchorPoint1, ref anchorPoint2, ref controlPoint) > flatnessSquared) | ||
| // //{ | ||
| // //2) Compute nessary values | ||
| // //segControl1 = (a1+c)/2 | ||
| // Vector2 segControl1; | ||
| // Vector2.Add(ref anchorPoint1, ref controlPoint, out segControl1); | ||
| // Vector2.Divide(ref segControl1, 2f, out segControl1); | ||
| // //segControl2 = (a1+c)/2 | ||
| // Vector2 segControl2; | ||
| // Vector2.Add(ref anchorPoint2, ref controlPoint, out segControl2); | ||
| // Vector2.Divide(ref segControl2, 2f, out segControl2); | ||
| // //segAnchor = (a1 + 3•c1 + 3•c2 + a2)/8 | ||
| // Vector2 segAnchor; | ||
| // Vector2.Multiply(ref controlPoint, 2f, out segAnchor); | ||
| // Vector2.Add(ref segAnchor, ref anchorPoint1, out segAnchor); | ||
| // Vector2.Add(ref segAnchor, ref anchorPoint2, out segAnchor); | ||
| // Vector2.Divide(ref segAnchor, 4f, out segAnchor); | ||
|
|
||
| // //3) Recurse segments | ||
| // foreach (var item in _createQuadraticBezierCurve(anchorPoint1, segAnchor, segControl1, flatnessSquared)) yield return item; | ||
| // yield return segAnchor; | ||
| // foreach (var item in _createQuadraticBezierCurve(segAnchor, anchorPoint2, segControl2, flatnessSquared)) yield return item; | ||
| // //} | ||
| //} | ||
| #endregion | ||
| } | ||
| } |
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