public static bool CatmullRomSegmentToCurve4(this PathWriter _writer,
double x0, double y0, //p0 //explicit x0 y0
double x1, double y1, //p1
double x2, double y2, //p2
double x3, double y3) //p3
{
//just experiment only,
//not correct now
//https://en.wikipedia.org/wiki/Centripetal_Catmull%E2%80%93Rom_spline
//https://stackoverflow.com/questions/30748316/catmull-rom-interpolation-on-svg-paths
double t0 = 0.0f,
t1 = CatmullRomGetT(t0, x0, y0, x1, y1),
t2 = CatmullRomGetT(t1, x1, y1, x2, y2),
t3 = CatmullRomGetT(t2, x2, y2, x3, y3);
if ((t0 == t1) || (t1 == t2) || (t2 == t3))
{
//invalid
_writer.LineTo(x1, y1);
_writer.LineTo(x2, y2);
return(false);
}
double c1 = (t2 - t1) / (t2 - t0),
c2 = (t1 - t0) / (t2 - t0),
d1 = (t3 - t2) / (t3 - t1),
d2 = (t2 - t1) / (t3 - t1);
double m1x = (t2 - t1) * (c1 * (x1 - x0) / (t1 - t0) + c2 * (x2 - x1) / (t2 - t1));
double m2x = (t2 - t1) * (d1 * (x2 - x1) / (t2 - t1) + d2 * (x3 - x2) / (t3 - t2));
double m1y = (t2 - t1) * (c1 * (y1 - y0) / (t1 - t0) + c2 * (y2 - y1) / (t2 - t1));
double m2y = (t2 - t1) * (d1 * (y2 - y1) / (t2 - t1) + d2 * (y3 - y2) / (t3 - t2));
//Q0 = P1
//Q1 = P1 + M1 / 3
//Q2 = P2 - M2 / 3
//Q3 = P2
_writer.LineTo(x1, y1);
_writer.Curve4(x1 + m1x / 3, y1 + m1y / 3, x2 - m2x / 3, y2 - m2y / 3, x2, y2);
return(true);
}
/// <summary>
/// draw line
/// </summary>
/// <param name="x1"></param>
/// <param name="y1"></param>
/// <param name="x2"></param>
/// <param name="y2"></param>
/// <param name="color"></param>
public override void DrawLine(double x1, double y1, double x2, double y2)
{
//BitmapExt
if (this.RenderQuality == RenderQualtity.Fast)
{
this._bxt.DrawLine(
(int)Math.Round(x1),
(int)Math.Round(y1),
(int)Math.Round(x2),
(int)Math.Round(y2),
this.strokeColor.ToARGB()
);
return;
}
//----------------------------------------------------------
//Agg
if (_orientation == DrawBoardOrientation.LeftBottom)
{
//as original
_lineGen.Clear();
_lineGen.MoveTo(x1, y1);
_lineGen.LineTo(x2, y2);
var v1 = GetFreeVxs();
_aggsx.Render(stroke.MakeVxs(_lineGen.Vxs, v1), this.strokeColor);
ReleaseVxs(ref v1);
}
else
{
//left-top
int h = this.Height;
_lineGen.Clear();
_lineGen.MoveTo(x1, h - y1);
_lineGen.LineTo(x2, h - y2);
var v1 = GetFreeVxs();
_aggsx.Render(stroke.MakeVxs(_lineGen.Vxs, v1), this.strokeColor);
ReleaseVxs(ref v1);
}
}
static void SplineCurveSegment(
PathWriter writer,
double x1, double y1,
double x2, double y2,
double x3, double y3,
double x4, double y4,
float tension)
{
//from SplineExtensions.cs
//MIT, 2009-2015, Rene Schulte and WriteableBitmapEx Contributors, https://github.com/teichgraf/WriteableBitmapEx
//
// Project: WriteableBitmapEx - WriteableBitmap extensions
// Description: Collection of draw spline extension methods for the WriteableBitmap class.
//
// Changed by: $Author: unknown $
// Changed on: $Date: 2015-03-05 18:18:24 +0100 (Do, 05 Mrz 2015) $
// Changed in: $Revision: 113191 $
// Project: $URL: https://writeablebitmapex.svn.codeplex.com/svn/trunk/Source/WriteableBitmapEx/WriteableBitmapSplineExtensions.cs $
// Id: $Id: WriteableBitmapSplineExtensions.cs 113191 2015-03-05 17:18:24Z unknown $
//
//
// Copyright © 2009-2015 Rene Schulte and WriteableBitmapEx Contributors
// Determine distances between controls points (bounding rect) to find the optimal stepsize
double minX = Math.Min(x1, Math.Min(x2, Math.Min(x3, x4)));
double minY = Math.Min(y1, Math.Min(y2, Math.Min(y3, y4)));
double maxX = Math.Max(x1, Math.Max(x2, Math.Max(x3, x4)));
double maxY = Math.Max(y1, Math.Max(y2, Math.Max(y3, y4)));
// Get slope
double lenx = maxX - minX;
double len = maxY - minY;
if (lenx > len)
{
len = lenx;
}
// Prevent division by zero
if (len != 0)
{
// Init vars
double step = STEP_FACTOR / len;
double tx1 = x2;
double ty1 = y2;
// Calculate factors
double sx1 = tension * (x3 - x1);
double sy1 = tension * (y3 - y1);
double sx2 = tension * (x4 - x2);
double sy2 = tension * (y4 - y2);
double ax = sx1 + sx2 + 2 * x2 - 2 * x3;
double ay = sy1 + sy2 + 2 * y2 - 2 * y3;
double bx = -2 * sx1 - sx2 - 3 * x2 + 3 * x3;
double by = -2 * sy1 - sy2 - 3 * y2 + 3 * y3;
// Interpolate
writer.LineTo(tx1, ty1);
double tx2, ty2;
for (double t = step; t <= 1; t += step)
{
double tSq = t * t;
tx2 = (ax * tSq * t + bx * tSq + sx1 * t + x2);
ty2 = (ay * tSq * t + by * tSq + sy1 * t + y2);
// Draw line //
//DrawLine(context, w, h, tx1, ty1, tx2, ty2, color);
writer.LineTo(tx2, ty2);
tx1 = tx2;
ty1 = ty2;
}
// Prevent rounding gap
writer.LineTo(x3, y3);
//DrawLine(context, w, h, tx1, ty1, x3, y3, color);
}
}