//------------------------------------------------------------------------------
double Area(OutRec outRec, bool UseFull64BitRange)
{
OutPt op = outRec.pts;
if (op == null) return 0;
if (UseFull64BitRange)
{
Int128 a = new Int128(0);
do
{
a += Int128.Int128Mul(op.pt.X + op.prev.pt.X, op.prev.pt.Y - op.pt.Y);
op = op.next;
} while (op != outRec.pts);
return a.ToDouble() / 2;
}
else
{
double a = 0;
do {
a = a + (op.pt.X + op.prev.pt.X) * (op.prev.pt.Y - op.pt.Y);
op = op.next;
} while (op != outRec.pts);
return a/2;
}
}
//------------------------------------------------------------------------------
public static double Area(Polygon poly)
{
int highI = poly.Count - 1;
if (highI < 2) return 0;
bool UseFullInt64Range = false;
RangeTest rt = TestRange(poly);
switch (rt)
{
case RangeTest.rtHi:
UseFullInt64Range = true;
break;
case RangeTest.rtError:
throw new ClipperException("Coordinate exceeds range bounds.");
}
if (UseFullInt64Range)
{
Int128 a = new Int128(0);
a = Int128.Int128Mul(poly[highI].X, poly[0].Y) -
Int128.Int128Mul(poly[0].X, poly[highI].Y);
for (int i = 0; i < highI; ++i)
a += Int128.Int128Mul(poly[i].X, poly[i + 1].Y) -
Int128.Int128Mul(poly[i + 1].X, poly[i].Y);
return a.ToDouble() / 2;
}
else
{
double area = (double)poly[highI].X * (double)poly[0].Y -
(double)poly[0].X * (double)poly[highI].Y;
for (int i = 0; i < highI; ++i)
area += (double)poly[i].X * (double)poly[i + 1].Y -
(double)poly[i + 1].X * (double)poly[i].Y;
return area / 2;
}
}
//------------------------------------------------------------------------------
public static double Area(Polygon poly)
{
int highI = poly.Count - 1;
if (highI < 2) return 0;
if (FullRangeNeeded(poly))
{
Int128 a = new Int128(0);
a = Int128.Int128Mul(poly[highI].X + poly[0].X, poly[0].Y - poly[highI].Y);
for (int i = 1; i <= highI; ++i)
a += Int128.Int128Mul(poly[i - 1].X + poly[i].X, poly[i].Y - poly[i - 1].Y);
return a.ToDouble() / 2;
}
else
{
double area = ((double)poly[highI].X + poly[0].X) * ((double)poly[0].Y - poly[highI].Y);
for (int i = 1; i <= highI; ++i)
area += ((double)poly[i - 1].X + poly[i].X) * ((double)poly[i].Y - poly[i -1].Y);
return area / 2;
}
}
