private static double SolveLineFactorT(double[] N, double[] pe, double[] p0, double[] pdiff, out LineClipType type)
{
double dominator = N[0] * pdiff[0] + N[1] * pdiff[1];
if (dominator < 0.0)
{
type = LineClipType.entering;
}
else
{
type = LineClipType.leaving;
}
if (dominator == 0.0)
{
return(1e10); // paralell lines...
}
return((N[0] * (pe[0] - p0[0]) + N[1] * (pe[1] - p0[1])) / dominator);
}
private static IPoint[] LiamBarsky(IEnvelope envelope, IPoint p1, IPoint p2, out LineClipType type)
{
IPoint[] points = new Point[2];
int code1 = CalculateLRBT(envelope, p1);
int code2 = CalculateLRBT(envelope, p2);
type = LineClipType.inside;
if (code1 == 0 && code2 == 0)
{
points[0] = p1;
points[1] = p2;
return(points);
}
if ((code1 & code2) != 0)
{
type = LineClipType.outside;
return(null);
}
double[] pdiff = { p2.X - p1.X, p2.Y - p1.Y };
double[] p0 = { p1.X, p1.Y };
double tpe = 1e10; //0.0;
double tpl = 1e10; //1.0;
for (int edge = 0; edge < 4; edge++)
{
double[] N = new double[2];
double[] pe = new double[2];
switch (edge)
{
case 0:
N[0] = -1.0; N[1] = 0.0;
pe[0] = envelope.minx; pe[1] = 0.0;
break;
case 1:
N[0] = 0.0; N[1] = -1.0;
pe[0] = 0.0; pe[1] = envelope.miny;
break;
case 2:
N[0] = 1.0; N[1] = 0.0;
pe[0] = envelope.maxx; pe[1] = 0.0;
break;
case 3:
N[0] = 0.0; N[1] = 1.0;
pe[0] = 0.0; pe[1] = envelope.maxy;
break;
}
double t = SolveLineFactorT(N, pe, p0, pdiff, out type);
if (t >= 0 && t <= 1.0)
{
if (type == LineClipType.entering && (t > tpe || tpe == 1e10))
{
tpe = t;
}
else if (type == LineClipType.leaving && (t < tpl || tpl == 1e10))
{
tpl = t;
}
}
}
if (tpe == 1e10 && tpl == 1e10)
{
type = LineClipType.outside;
return(null);
}
double tpe_ = (tpe != 1e10) ? tpe : 0.0;
double tpl_ = (tpl != 1e10) ? tpl : 1.0;
points[0] = new Point(p1.X + tpe_ * pdiff[0], p1.Y + tpe_ * pdiff[1]);
points[1] = new Point(p1.X + tpl_ * pdiff[0], p1.Y + tpl_ * pdiff[1]);
code1 = CalculateLRBT(envelope, points[0]);
code2 = CalculateLRBT(envelope, points[0]);
if (code1 != 0 || code2 != 0)
{
type = LineClipType.outside;
return(null);
}
if (tpl_ < 1.0)
{
type = LineClipType.leaving;
return(points);
}
else if (tpe_ > 0.0)
{
type = LineClipType.entering;
return(points);
}
return(null);
}