private List <BezierCurvePoint> CalculateCurveControlPoints(List <BezierCurvePoint> points)
{
var dx1 = points[0].X - points[1].X;
var dy1 = points[0].Y - points[1].Y;
var dx2 = points[1].X - points[2].X;
var dy2 = points[1].Y - points[2].Y;
var m1 = new BezierCurvePoint((points[0].X + points[1].X) / 2, (points[0].Y + points[1].Y) / 2);
var m2 = new BezierCurvePoint((points[1].X + points[2].X) / 2, (points[1].Y + points[2].Y) / 2);
var l1 = Math.Sqrt(dx1 * dx1 + dy1 * dy1);
var l2 = Math.Sqrt(dx2 * dx2 + dy2 * dy2);
var dxm = m1.X - m2.X;
var dym = m1.Y - m2.Y;
var k = l2 / (l1 + l2);
var cm = new BezierCurvePoint(m2.X + dxm * k, m2.Y + dym * k);
var tx = points[1].X - cm.X;
var ty = points[1].Y - cm.Y;
return(new List <BezierCurvePoint>()
{
new BezierCurvePoint(m1.X + tx, m1.Y + ty),
new BezierCurvePoint(m2.X + tx, m2.Y + ty),
});
}
private void AddPoint(BezierCurvePoint point)
{
this.Points.Add(point);
if (this.Points.Count > 2)
{
if (this.Points.Count == 3)
{
this.Points.Insert(0, this.Points[0]);
}
var startPoint = this.Points[1];
var controlPoint1 = this.CalculateCurveControlPoints(new List <BezierCurvePoint>()
{
this.Points[0], this.Points[1], this.Points[2],
})[1];
var controlPoint2 = this.CalculateCurveControlPoints(new List <BezierCurvePoint>()
{
this.Points[1], this.Points[2], this.Points[3],
})[0];
var endPoint = this.Points[2];
var curve = new BezierCurve(startPoint, controlPoint1, controlPoint2, endPoint);
this.AddCurve(curve);
this.Points.RemoveAt(0);
}
}
public BezierCurve(
BezierCurvePoint startPoint,
BezierCurvePoint controlPoint1,
BezierCurvePoint controlPoint2,
BezierCurvePoint endPoint)
{
this.StartPoint = startPoint;
this.ControlPoint1 = controlPoint1;
this.ControlPoint2 = controlPoint2;
this.EndPoint = endPoint;
}
private void DrawPoint(BezierCurvePoint point, double width)
{
this.MyCanvas.Children.Add(
new Ellipse()
{
HorizontalAlignment = HorizontalAlignment.Left,
VerticalAlignment = VerticalAlignment.Top,
Width = width,
Height = width,
Fill = this.penColor,
Stroke = this.penColor,
Margin = new Thickness(point.X, point.Y, 0, 0),
});
}
private void DrawCurve(BezierCurve curve, double startWidth, double endWidth)
{
var widthDelta = endWidth - startWidth;
var drawSteps = Math.Floor(curve.Length);
for (int i = 0; i < drawSteps; i++)
{
var t = i / drawSteps;
var tt = t * t;
var ttt = tt * t;
var u = 1 - t;
var uu = u * u;
var uuu = uu * u;
var x = curve.StartPoint.X * uuu + 3 * curve.ControlPoint1.X * uu * t + 3 * curve.ControlPoint2.X * u * tt + curve.EndPoint.X * ttt;
var y = curve.StartPoint.Y * uuu + 3 * curve.ControlPoint1.Y * uu * t + 3 * curve.ControlPoint2.Y * u * tt + curve.EndPoint.Y * ttt;
var point = new BezierCurvePoint(x, y);
var width = startWidth + ttt * widthDelta;
this.DrawPoint(point, width);
}
}
private void StrokeDraw(BezierCurvePoint point)
{
this.DrawPoint(point, this.LastWidth);
}
private double DistanceTo(BezierCurvePoint point)
{
return(Math.Sqrt(Math.Pow(this.X - point.X, 2) + Math.Pow(this.Y - point.Y, 2)));
}
public double VelocityFrom(BezierCurvePoint start)
{
return(this.Time != start.Time ? this.DistanceTo(start) / (this.Time - start.Time).Milliseconds : 0);
}
