/*---------------------------------------------------------------------
* Performs the Graham scan on an array of angularly sorted points P.
* ---------------------------------------------------------------------*/
private cVertexList Graham()
{
cVertexList top;
int i;
// cVertex p1, p2; /* Top two points on stack. */
/* Initialize stack. */
top = new cVertexList();
cVertex v1 = new cVertex(list.head.Point.X, list.head.Point.Y);
v1.IndexInModel = list.head.IndexInModel;
v1.IsProcessed = list.head.IsProcessed;
cVertex v2 = new cVertex(list.head.NextVertex.Point.X, list.head.NextVertex.Point.Y);
v2.IndexInModel = list.head.NextVertex.IndexInModel;
v2.IsProcessed = list.head.NextVertex.IsProcessed;
Push(v1, top);
Push(v2, top);
// Bottom two elements will never be removed.
i = 2;
while (i < list.n)
{
cVertex v3 = new cVertex(list.GetElement(i).Point.X, list.GetElement(i).Point.Y);
v3.IsProcessed = list.GetElement(i).IsProcessed;
v3.IndexInModel = list.GetElement(i).IndexInModel;
if (v1.Point.Left(top.head.PrevVertex.Point, top.head.PrevVertex.PrevVertex.Point, v3.Point))
{
Push(v3, top);
i++;
}
else
{
if (top.n > 2)
{
Pop(top);
}
}
}
return(top);
}
private void Sort(cVertexList a, int lo0, int hi0)
{
if (lo0 >= hi0)
{
return;
}
cVertex mid = new cVertex();
mid = a.GetElement(hi0);
int lo = lo0;
int hi = hi0 - 1;
while (lo <= hi)
{
while (lo <= hi && ((Compare(a.GetElement(lo), mid) == 1) || (Compare(a.GetElement(lo), mid) == 0)))
{
lo++;
}
while (lo <= hi && ((Compare(a.GetElement(hi), mid) == -1) || (Compare(a.GetElement(hi), mid) == 0)))
{
hi--;
}
if (lo < hi)
{
Swap(a.GetElement(lo), a.GetElement(hi));
}
}
Swap(a.GetElement(lo), a.GetElement(hi0));
Sort(a, lo0, lo - 1);
Sort(a, lo + 1, hi0);
}
private int ReadVertices()
{
cVertex v = P.head;
int i = 0;
do
{
v.IndexInModel = i++;
v.IsProcessed = true;
v = v.NextVertex;
} while (v != P.head);
v = B.head;
do
{
cVertex temp = new cVertex(v.Point.X, v.Point.Y);
P.InsertBeforeHead(temp);
v = v.NextVertex;
} while (v != B.head);
v = P.GetElement(n); i = 0;
do
{
/* Reflect secondary polygon */
v.Point.X = -v.Point.X;
v.Point.Y = -v.Point.Y;
v.IndexInModel = i++;
v.IsProcessed = false;
v = v.NextVertex;
} while (v != P.head);
double xmin, ymin, xmax, ymax; /* Primary min & max */
double sxmin, symin, sxmax, symax; /* Secondary min & max */
int mp, ms; /* i index of max (u-r) primary and secondary points */
xmin = ymin = xmax = ymax = 0;
sxmin = symin = sxmax = symax = 0;
mp = ms = 0; v = P.head;
xmin = xmax = v.Point.X;
ymin = ymax = v.Point.Y;
mp = 0; i = 1;
v = v.NextVertex;
cVertex startB = P.GetElement(n);
do
{
if (v.Point.X > xmax)
{
xmax = v.Point.X;
}
else if (v.Point.X < xmin)
{
xmin = v.Point.X;
}
if (v.Point.Y > ymax)
{
ymax = v.Point.Y; mp = i;
}
else if (v.Point.Y == ymax && (v.Point.X > P.GetElement(mp).Point.X))
{
mp = i;
}
else if (v.Point.Y < ymin)
{
ymin = v.Point.Y;
}
v = v.NextVertex; i++;
} while (v != startB);
/*System.Diagnostics.Debug.WriteLine("Index of upper rightmost primary, i=mp = "+mp);*/
v = startB;
sxmin = sxmax = v.Point.X;
symin = symax = v.Point.Y;
ms = n; v = v.NextVertex; i = 1;
do
{
if (v.Point.X > sxmax)
{
sxmax = v.Point.X;
}
else if (v.Point.X < sxmin)
{
sxmin = v.Point.X;
}
if (v.Point.Y > symax)
{
symax = v.Point.Y; ms = i;
}
else if (v.Point.Y == symax && (v.Point.X > P.GetElement(ms).Point.X))
{
ms = i;
}
else if (v.Point.Y < symin)
{
symin = v.Point.Y;
}
v = v.NextVertex; i++;
} while (v != P.head.NextVertex);
/*System.Diagnostics.Debug.WriteLine("Index of upper rightmost secondary, i=ms = "+ms);*/
/* Compute the start point: upper rightmost of both. */
System.Diagnostics.Debug.WriteLine("p0:");
p0.PrintPoint();
System.Diagnostics.Debug.WriteLine("mp is: " + mp);
System.Diagnostics.Debug.WriteLine("mp element:" + P.GetElement(mp).Point.X + "," + P.GetElement(mp).Point.Y);
AddVec(p0, P.GetElement(mp).Point, p0);
System.Diagnostics.Debug.WriteLine("p0 after addvec:");
p0.PrintPoint();
System.Diagnostics.Debug.WriteLine("ms is: " + ms);
System.Diagnostics.Debug.WriteLine("ms element:" + P.GetElement(ms).Point.X + "," + P.GetElement(ms).Point.Y);
// AddVec( p0, P.GetElement(ms).v, p0 );
System.Diagnostics.Debug.WriteLine("p0 after another addvec:");
p0.PrintPoint();
return(mp);
}