public static Direction GetNormal(PointUV uv, double p, double q, double circleAngle, Vector inverseOffset, bool isInverted)
{
double delta = 0.001;
var deltaU = VectorUV.Create(delta, 0);
var deltaV = VectorUV.Create(0, delta);
PointUV uv00 = uv - deltaU;
PointUV uv01 = uv + deltaU;
PointUV uv10 = uv - deltaV;
PointUV uv11 = uv + deltaV;
Point pCenter = Lawson.Evaluate(uv, p, q, circleAngle, inverseOffset, isInverted);
var pxxs = new Point[] {
Lawson.Evaluate(uv00, p, q, circleAngle, inverseOffset, isInverted),
Lawson.Evaluate(uv01, p, q, circleAngle, inverseOffset, isInverted),
Lawson.Evaluate(uv10, p, q, circleAngle, inverseOffset, isInverted),
Lawson.Evaluate(uv11, p, q, circleAngle, inverseOffset, isInverted)
};
var sum = Vector.Zero;
foreach (Point pxx in pxxs)
{
sum += pxx - pCenter;
}
if (sum != Vector.Zero)
{
return(sum.Direction);
}
return(Vector.Cross(pxxs[1] - pxxs[0], pxxs[1] - pxxs[2]).Direction);
}
public static Direction GetNormal(PointUV uv, double p, double q, double circleAngle, Vector inverseOffset, bool isInverted)
{
double delta = 0.001;
var deltaU = VectorUV.Create(delta, 0);
var deltaV = VectorUV.Create(0, delta);
PointUV uv00 = uv - deltaU;
PointUV uv01 = uv + deltaU;
PointUV uv10 = uv - deltaV;
PointUV uv11 = uv + deltaV;
Vector du =
Lawson.Evaluate(uv00, p, q, circleAngle, inverseOffset, isInverted) -
Lawson.Evaluate(uv01, p, q, circleAngle, inverseOffset, isInverted)
;
Vector dv =
Lawson.Evaluate(uv10, p, q, circleAngle, inverseOffset, isInverted) -
Lawson.Evaluate(uv11, p, q, circleAngle, inverseOffset, isInverted)
;
return(Vector.Cross(du, dv).Direction);
}