private static bool TestQuadrant(CornerQuadrant quadrant, double x, double y)
{
switch (quadrant)
{
case CornerQuadrant.UpperRight:
return x > -VGConstants.FuzzGeneral && y < VGConstants.FuzzGeneral;
case CornerQuadrant.UpperLeft:
return x < VGConstants.FuzzGeneral && y < VGConstants.FuzzGeneral;
case CornerQuadrant.LowerLeft:
return x < VGConstants.FuzzGeneral && y > -VGConstants.FuzzGeneral;
//case CornerQuadrant.LowerRight:
default:
return x > -VGConstants.FuzzGeneral && y > -VGConstants.FuzzGeneral;
}
}
private static PointD? FindCornerHit(PointD cornerCenter, PointD samplePoint, double slope, double radius, CornerQuadrant quadrant)
{
double ccx = cornerCenter.X;
double ccy = cornerCenter.Y;
double px = samplePoint.X - ccx;
double py = samplePoint.Y - ccy;
double quadA = 1 + slope * slope;
double sharedQuadPart = py - slope * px;
double quadB = (slope + slope) * sharedQuadPart;
double quadC = sharedQuadPart * sharedQuadPart - radius * radius;
double discriminant = quadB * quadB - 4 * quadA * quadC;
double solvedX;
double solvedY;
if (VGConstants.FuzzZero(discriminant, VGConstants.FuzzGeneral))
{
solvedX = -quadB / (quadA + quadA);
solvedY = slope * (solvedX - px) + py;
return TestQuadrant(quadrant, solvedX, solvedY) ? new PointD(solvedX + ccx, solvedY + ccy) : new PointD?();
}
else if (discriminant < 0)
{
return null;
}
else
{
discriminant = Math.Sqrt(discriminant);
solvedX = (-quadB + discriminant) / (quadA + quadA);
solvedY = slope * (solvedX - px) + py;
bool solvedInQuadrant = TestQuadrant(quadrant, solvedX, solvedY);
double solvedXAlternate = (-quadB - discriminant) / (quadA + quadA);
double solvedYAlternate = slope * (solvedXAlternate - px) + py;
bool solvedInQuadrantAlternate = TestQuadrant(quadrant, solvedXAlternate, solvedYAlternate);
if (solvedInQuadrant)
{
if (solvedInQuadrantAlternate)
{
double xDif = px - solvedX;
double yDif = py - solvedY;
double xDifAlternate = px - solvedXAlternate;
double yDifAlternate = py - solvedYAlternate;
if ((xDif * xDif + yDif * yDif) > (xDifAlternate * xDifAlternate + yDifAlternate * yDifAlternate))
{
solvedX = solvedXAlternate;
solvedY = solvedYAlternate;
}
}
}
else if (solvedInQuadrantAlternate)
{
solvedX = solvedXAlternate;
solvedY = solvedYAlternate;
}
else
{
return null;
}
}
return new PointD(solvedX + ccx, solvedY + ccy);
}