public static void Draw(Context grw, Arc3PointsElement arc)
{
const double eps = 0.000001;
double arcStart;
double arcEnd;
if (arc.Foregraund != null)
{
grw.SetSourceRGB(
arc.Foregraund.Red,
arc.Foregraund.Green,
arc.Foregraund.Blue);
}
var arcCenter = new PointD(0, 0);
var yDeltaA = arc.Middle.GeometryY - arc.Start.GeometryY;
var xDeltaA = arc.Middle.GeometryX - arc.Start.GeometryX;
var yDeltaB = arc.End.GeometryY - arc.Middle.GeometryY;
var xDeltaB = arc.End.GeometryX - arc.Middle.GeometryX;
//common case - no perpendicular & collinear lines
if ((Math.Abs(xDeltaA) > eps)
&& (Math.Abs(xDeltaB) > eps)
&& (Math.Abs(yDeltaA) > eps)
&& (Math.Abs(yDeltaB) > eps))
{
var aSlope = yDeltaA / xDeltaA;
var bSlope = yDeltaB / xDeltaB;
if (Math.Abs(aSlope - bSlope) <= eps)
{
//throw new ArgumentException("3 points lie at one line");
return;
}
arcCenter.X = (aSlope * bSlope * (arc.Start.GeometryY - arc.End.GeometryY)
+ bSlope * (arc.Start.GeometryX + arc.Middle.GeometryX)
- aSlope * (arc.Middle.GeometryX + arc.End.GeometryX)) / (2 * (bSlope - aSlope));
arcCenter.Y = -1 * (arcCenter.X - (arc.Start.GeometryX + arc.Middle.GeometryX) / 2)
/ aSlope + (arc.Start.GeometryY + arc.Middle.GeometryY) / 2;
}
else
{
//vertical or horizontal cases
if (Math.Abs(xDeltaA) <= eps)
{
//1st is vertical
if (Math.Abs(xDeltaB) <= eps)
{
//2nd is vertical too
//throw new ArgumentException("Both lines are vertical");
return;
}
if (Math.Abs(yDeltaB) > eps)
{
// 2nd is not horizontal
//throw new NotImplementedException("Only first vertical");
return;
}
//square angle
arcCenter.X = 0.5 * (arc.Middle.GeometryX + arc.End.GeometryX);
arcCenter.Y = 0.5 * (arc.Start.GeometryY + arc.Middle.GeometryY);
}
if (Math.Abs(yDeltaA) <= eps)
{
//1st is horizontal
if (Math.Abs(yDeltaB) <= eps)
{
//2nd is horizontal too
//throw new ArgumentException("Both line are horizontal");
return;
}
if (Math.Abs(xDeltaB) > eps)
{
//1st is not horizontal
//throw new NotImplementedException("Only first horizontal");
return;
}
//square angle
arcCenter.X = 0.5 * (arc.Start.GeometryX + arc.Middle.GeometryX);
arcCenter.Y = 0.5 * (arc.Middle.GeometryY + arc.End.GeometryY);
}
}
//radius
var arcRadius = Math.Sqrt(Math.Pow(arc.Start.GeometryX - arcCenter.X, 2)
+ Math.Pow(arc.Start.GeometryY - arcCenter.Y, 2));
//arc angles
var xStartDelta = arc.Start.GeometryX - arcCenter.X;
var yStartDelta = arc.Start.GeometryY - arcCenter.Y;
var xEndDelta = arc.End.GeometryX - arcCenter.X;
var yEndDelta = arc.End.GeometryY - arcCenter.Y;
//start of arc
if (Math.Abs(xStartDelta) < eps)
{
if (yStartDelta < 0.0)
{
arcStart = -0.5 * Math.PI;
}
else
{
arcStart = 0.5 * Math.PI;
}
}
else
{
arcStart = Math.Atan2(yStartDelta, xStartDelta);
}
//end of arc
if (Math.Abs(xEndDelta) < eps)
{
if (yEndDelta < 0.0)
{
arcEnd = -0.5 * Math.PI;
}
else
{
arcEnd = 0.5 * Math.PI;
}
}
else
{
arcEnd = Math.Atan2(yEndDelta, xEndDelta);
}
if (Math.Sign((arc.Middle.GeometryX - arc.Start.GeometryX)
* (arc.Middle.GeometryY - arc.End.GeometryY)
- (arc.Middle.GeometryY - arc.Start.GeometryY)
* (arc.Middle.GeometryX - arc.End.GeometryX)) < 0)
{
grw.Arc(
arcCenter.X,
arcCenter.Y,
arcRadius,
arcStart,
arcEnd);
}
else
{
grw.ArcNegative(
arcCenter.X,
arcCenter.Y,
arcRadius,
arcStart,
arcEnd);
}
grw.Stroke();
}
public static void Draw(Context grw, Arc3PointsElement arc)
{
const double eps = 0.000001;
double arcStart;
double arcEnd;
if (arc.Foregraund != null)
{
grw.SetSourceRGB(
arc.Foregraund.Red,
arc.Foregraund.Green,
arc.Foregraund.Blue);
}
var arcCenter = new PointD(0, 0);
var yDeltaA = arc.Middle.GeometryY - arc.Start.GeometryY;
var xDeltaA = arc.Middle.GeometryX - arc.Start.GeometryX;
var yDeltaB = arc.End.GeometryY - arc.Middle.GeometryY;
var xDeltaB = arc.End.GeometryX - arc.Middle.GeometryX;
//common case - no perpendicular & collinear lines
if ((Math.Abs(xDeltaA) > eps) &&
(Math.Abs(xDeltaB) > eps) &&
(Math.Abs(yDeltaA) > eps) &&
(Math.Abs(yDeltaB) > eps))
{
var aSlope = yDeltaA / xDeltaA;
var bSlope = yDeltaB / xDeltaB;
if (Math.Abs(aSlope - bSlope) <= eps)
{
//throw new ArgumentException("3 points lie at one line");
return;
}
arcCenter.X = (aSlope * bSlope * (arc.Start.GeometryY - arc.End.GeometryY)
+ bSlope * (arc.Start.GeometryX + arc.Middle.GeometryX)
- aSlope * (arc.Middle.GeometryX + arc.End.GeometryX)) / (2 * (bSlope - aSlope));
arcCenter.Y = -1 * (arcCenter.X - (arc.Start.GeometryX + arc.Middle.GeometryX) / 2)
/ aSlope + (arc.Start.GeometryY + arc.Middle.GeometryY) / 2;
}
else
{
//vertical or horizontal cases
if (Math.Abs(xDeltaA) <= eps)
{
//1st is vertical
if (Math.Abs(xDeltaB) <= eps)
{
//2nd is vertical too
//throw new ArgumentException("Both lines are vertical");
return;
}
if (Math.Abs(yDeltaB) > eps)
{
// 2nd is not horizontal
//throw new NotImplementedException("Only first vertical");
return;
}
//square angle
arcCenter.X = 0.5 * (arc.Middle.GeometryX + arc.End.GeometryX);
arcCenter.Y = 0.5 * (arc.Start.GeometryY + arc.Middle.GeometryY);
}
if (Math.Abs(yDeltaA) <= eps)
{
//1st is horizontal
if (Math.Abs(yDeltaB) <= eps)
{
//2nd is horizontal too
//throw new ArgumentException("Both line are horizontal");
return;
}
if (Math.Abs(xDeltaB) > eps)
{
//1st is not horizontal
//throw new NotImplementedException("Only first horizontal");
return;
}
//square angle
arcCenter.X = 0.5 * (arc.Start.GeometryX + arc.Middle.GeometryX);
arcCenter.Y = 0.5 * (arc.Middle.GeometryY + arc.End.GeometryY);
}
}
//radius
var arcRadius = Math.Sqrt(Math.Pow(arc.Start.GeometryX - arcCenter.X, 2)
+ Math.Pow(arc.Start.GeometryY - arcCenter.Y, 2));
//arc angles
var xStartDelta = arc.Start.GeometryX - arcCenter.X;
var yStartDelta = arc.Start.GeometryY - arcCenter.Y;
var xEndDelta = arc.End.GeometryX - arcCenter.X;
var yEndDelta = arc.End.GeometryY - arcCenter.Y;
//start of arc
if (Math.Abs(xStartDelta) < eps)
{
if (yStartDelta < 0.0)
{
arcStart = -0.5 * Math.PI;
}
else
{
arcStart = 0.5 * Math.PI;
}
}
else
{
arcStart = Math.Atan2(yStartDelta, xStartDelta);
}
//end of arc
if (Math.Abs(xEndDelta) < eps)
{
if (yEndDelta < 0.0)
{
arcEnd = -0.5 * Math.PI;
}
else
{
arcEnd = 0.5 * Math.PI;
}
}
else
{
arcEnd = Math.Atan2(yEndDelta, xEndDelta);
}
if (Math.Sign((arc.Middle.GeometryX - arc.Start.GeometryX)
* (arc.Middle.GeometryY - arc.End.GeometryY)
- (arc.Middle.GeometryY - arc.Start.GeometryY)
* (arc.Middle.GeometryX - arc.End.GeometryX)) < 0)
{
grw.Arc(
arcCenter.X,
arcCenter.Y,
arcRadius,
arcStart,
arcEnd);
}
else
{
grw.ArcNegative(
arcCenter.X,
arcCenter.Y,
arcRadius,
arcStart,
arcEnd);
}
/* grw.MoveTo (
* arc.Start.GeometryX,
* arc.Start.GeometryY);
* grw.LineTo (
* arc.Middle.GeometryX,
* arc.Middle.GeometryY);
* grw.LineTo (
* arc.End.GeometryX,
* arc.End.GeometryY);*/
grw.Stroke();
}
