//Helper method that calculates the angles of the first and last points
//of the curve
private void calculateAngles(Point p1, Point p2, Point p3, double length)
{
this.startangle = Dewlib.RestrictRange(Math.Atan2(p1.y - center.y, p1.x - center.x), 0, 2 * Math.PI);
double midangle = Dewlib.RestrictRange(Math.Atan2(p2.y - center.y, p2.x - center.x), 0, 2 * Math.PI);
//NOT the last point of this curve
//Only used to calculate the direction of the curve
double lastangle = Dewlib.RestrictRange(Math.Atan2(p3.y - center.y, p3.x - center.x), 0, 2 * Math.PI);
if (startangle >= midangle && midangle >= lastangle)
{
clockwise = false;
}
else if (startangle >= lastangle && lastangle >= midangle)
{
clockwise = true;
}
else if (midangle >= startangle && startangle >= lastangle)
{
clockwise = true;
}
else if (midangle >= lastangle && lastangle >= startangle)
{
clockwise = false;
}
else if (lastangle >= startangle && startangle >= midangle)
{
clockwise = false;
}
else if (lastangle >= midangle && midangle >= startangle)
{
clockwise = true;
}
//Use the arclength to calculate the final angle since the last control point
//of the slider is NOT the last point of the curve
//This is an angle differential since the formula assumes a start from an angle of 0
double anglediff = length / radius;
if (clockwise)
{
this.endangle = Dewlib.RestrictRange(startangle + anglediff, 0, 2 * Math.PI);
}
else
{
this.endangle = Dewlib.RestrictRange(startangle - anglediff, 0, 2 * Math.PI);
}
}
//Gets a point on the approximated curve on the circle
//Goes from 0 to 1, where 0 is the starting point and 1 is the ending point
public Point GetPoint(double t)
{
//TODO: Make exception more useful
if (t < 0 || t > 1)
{
throw new ArgumentOutOfRangeException();
}
double angle;
double anglediff;
if (clockwise)
{
if (endangle - startangle > 0)
{
anglediff = endangle - startangle;
}
else
{
anglediff = endangle + ((2 * Math.PI) - startangle);
}
angle = Dewlib.RestrictRange(t * anglediff + startangle, 0, 2 * Math.PI);
}
else
{
if (startangle - endangle > 0)
{
anglediff = startangle - endangle;
}
else
{
anglediff = startangle + ((2 * Math.PI) - endangle);
}
angle = Dewlib.RestrictRange(-t * anglediff + startangle, 0, 2 * Math.PI);
}
Point accessed = new Point();
accessed.x = center.x + radius * Math.Cos(angle);
accessed.y = center.y + radius * Math.Sin(angle);
return(accessed);
}
