public Fraction Tangent(LineFr that) // tan(theta) = (m1 - m2)/(1 + (m1*m2))
{
if (isParallelTo(that))
{
return(Fraction.Zero);
}
if (IsVertical())
{
if (that.IsHorizontal())
{
return(-1);
}
return(Slope.Inverse());
}
if (that.IsVertical())
{
if (that.IsHorizontal())
{
return(-1);
}
return(Slope);
}
if (isPerpendicularTo(that))
{
return(-1);
}
return((Slope - that.Slope) / (1 + Slope * that.Slope));
}
private Fraction XIntercept(LineFr that) // y = slope* x + constant: (b2 - b1) / (m1 - m2)
{
if (IsVertical())
{
return(Constant);
}
if (that.IsVertical())
{
return(that.Constant);
}
return((that.Constant - Constant) / (Slope - that.Slope));
}
public bool isPerpendicularTo(LineFr that)
{
if (IsVertical())
{
return(that.IsHorizontal());
}
if (that.IsVertical())
{
return(IsHorizontal());
}
return(Slope * that.Slope == -1);
}
public bool IsRightOf(LineFr line)
{
if (line.Contains(this))
{
return(false);
}
if (line.IsHorizontal())
{
return(Y < line.YIntercept());
}
if (line.IsVertical())
{
return(X > line.XIntercept());
}
var linePointNullable = line.Intersection(LineFr.Vertical(Fraction.Zero));
if (linePointNullable == null)
{
throw new ArgumentException("Wartość linePoint nie może wynosić null");
}
var linePoint = (PointFr)linePointNullable;
var temp = new LineFr(this, linePoint);
if (Y < linePoint.Y)
{
if (line.Slope < 0) // a
{
return(temp.Slope < 0 && temp.Slope > line.Slope);
}
return(temp.Slope < 0 || temp.Slope > line.Slope); // b
}
if (Y > linePoint.Y)
{
if (line.Slope < 0) // c
{
return(temp.Slope >= 0 || temp.Slope < line.Slope);
}
return(temp.Slope >= 0 && temp.Slope < line.Slope); // d
}
return(IsRightOf(linePoint)); // 'this' ma taką samą współrzędną y jak 'linePoint'
}