//***************************************************************
// X p a n d I n i t
//***************************************************************
void XpandInit(ref SurfaceGrid Zgrid, ref ScatteredData Data)
{
NumXcoords = Convert.ToInt32(Zgrid.xsize);
NumYcoords = Convert.ToInt32(Zgrid.ysize);
TotalGridPoints = (long)NumXcoords * (long)NumYcoords;
xIndex = yIndex = 0;
NumberDone = TotalRange = TotalShells = 0;
NumDataPoints = Data.Size;
if (NumDataPoints < 3)
{
return;
}
xGridMin = Zgrid.x(0);
xGridMax = Zgrid.x(NumXcoords - 1);
yGridMin = Zgrid.y(0);
yGridMax = Zgrid.y(NumYcoords - 1);
float xRange = Data.xMax - Data.xMin;
float yRange = Data.yMax - Data.yMin;
float Volume = xRange * yRange;
float VolPerPoint = Volume / ((float)NumDataPoints / (float)nSample);
Radius = (float)Math.Sqrt(VolPerPoint / Math.PI);
Diameter = Radius * 2;
DiameterSq = Diameter * Diameter;
xyStopDistSq = DiameterSq * DensityStopRatio * DensityStopRatio;
EdgeSenseDistSq = DiameterSq * EdgeSenseFactor * EdgeSenseFactor;
LocateInit(ref Data, ref Zgrid);
}
//**************************************************************
// X p a n d
// Generate the entire grid in one call.
//*************************************************************
public Xpand(ref SurfaceGrid Zgrid, ref ScatteredData RandomData)
{
XpandInit(ref Zgrid, ref RandomData);
while (XpandPoint(ref Zgrid, ref RandomData))
{
;
}
}
//**************************************************************
// L o c a t e I n i t
//**************************************************************
static void LocateInit(ref ScatteredData Data, ref SurfaceGrid Grid)
{
int ix = 0, iy = 0;
Locator.New(NumDataPoints, NumXcoords, NumYcoords);
for (long i = 0; i < NumDataPoints; i += nSample)
{
if (LocateGridX(ref ix, ref iy, Data.X[i], Data.Y[i], ref Grid))
{
Locator.setnext(i, ix, iy);
}
}
Locator.Sort();
}
//**********************************************************************
// S c a n O n e G r i d
//**********************************************************************
static void ScanOneGrid(int i, int j, ref ScatteredData Data, ref SurfaceGrid Grid)
{
long GotOne;
for (int n = 0; true; n++)
{
GotOne = Locator.Search(i, j, n);
if (GotOne < 0)
{
return;
}
PutInOctant(Grid.x(xIndex), Grid.y(yIndex), ref Data, GotOne);
TotalRange++;
}
}
//******************************************************************
// X p a n d P o i n t
//
// Evaluates one grid intersection only and advances indexes so
// the next call will evaluate the next one.
//******************************************************************
bool XpandPoint(ref SurfaceGrid Zgrid, ref ScatteredData RandomData)
{
float Zvalue;
//assert( xIndex < NumXcoords );
//assert( yIndex < NumYcoords );
if (NumDataPoints < 3)
{
return(false);
}
// Select the closest point in each octant surround the grid point.
SelectPoints(ref RandomData, ref Zgrid);
// Check if point can be included and if so.. calculate it.
if (IncludeGridPoint() > 0)
{
Zvalue = WeightedAverage(ref RandomData);
}
else
{
Zvalue = UndefinedZ;
}
Zgrid.zset(xIndex, yIndex, Zvalue);
// Move to next grid intersection....
++xIndex;
if (xIndex >= NumXcoords)
{
++yIndex; xIndex = 0;
}
if (yIndex >= NumYcoords)
{
Locator.New(0, NumXcoords, NumYcoords); return(false);
}
++NumberDone;
//assert( NumberDone <= TotalGridPoints);
return(true);
}
//**************************************************************
// L o c a t e G r i d X
//**************************************************************
static bool LocateGridX(ref int ix, ref int iy, float xLocn, float yLocn, ref SurfaceGrid Grid)
{
// Finds the closest grid intersection to data point i.
// Return's 1 if successful,
// 0 if data point is too far away from the intersection.
int test = 0,
nx, ny,
top,
bot;
float distance;
// check to see if point too far outside the grid perimeter.
distance = xGridMin - xLocn;
if (xLocn < xGridMin && distance * distance > xyStopDistSq)
{
return(false);
}
distance = xGridMax - xLocn;
if (xLocn > xGridMax && distance * distance > xyStopDistSq)
{
return(false);
}
distance = yGridMin - yLocn;
if (yLocn < yGridMin && distance * distance > xyStopDistSq)
{
return(false);
}
distance = yGridMax - yLocn;
if (yLocn > yGridMax && distance * distance > xyStopDistSq)
{
return(false);
}
// Binary search for closest in x.
nx = NumXcoords;
top = nx - 1;
bot = 0;
while ((top - bot) > 1)
{
test = (top - bot) / 2 + bot;
if (xLocn > Grid.x(test))
{
bot = test;
}
else
{
top = test;
}
}
float dist = Math.Abs(xLocn - Grid.x(test));
if (test < (nx - 1))
{
if (Math.Abs(xLocn - Grid.x(test + 1)) < dist)
{
test++;
}
}
if (test > 0)
{
if (Math.Abs(xLocn - Grid.x(test - 1)) < dist)
{
test--;
}
}
//assert( test >= 0 && test < nx );
ix = test;
// Do the same for closest in y.
ny = NumYcoords;
top = ny - 1;
bot = 0;
while ((top - bot) > 1)
{
test = (top - bot) / 2 + bot;
if (yLocn > Grid.y(test))
{
bot = test;
}
else
{
top = test;
}
}
dist = Math.Abs(yLocn - Grid.y(test));
if (test < (ny - 1))
{
if (Math.Abs(yLocn - Grid.y(test + 1)) < dist)
{
test++;
}
}
if (test > 0)
{
if (Math.Abs(yLocn - Grid.y(test - 1)) < dist)
{
test--;
}
}
//assert( test >= 0 && test < ny);
iy = test;
return(true);
}
// ***************************************************************
// S e l e c t P o i n t s
//*****************************************************************
static void SelectPoints(ref ScatteredData Data, ref SurfaceGrid Grid)
// This routine will search the array of Data points looking for
// the closest point in each of the 8 octants surrounding the grid
// coordinate currently being evaluated (at location x, y).
{
int Start,
End,
Row,
Column;
float TestDist;
bool TopDone = false; // These are logical flags controlling the
bool BottomDone = false; // Shelling process.
bool LeftDone = false;
bool RightDone = false;
int i;
// Zero out the arrays which keep track of closest point and its distance.
for (i = 0; i < 8; i++)
{
PointInOctant[i] = -1;
PointDistSquared[i] = 0.0f;
}
NoFound = 0;
ScanOneGrid(xIndex, yIndex, ref Data, ref Grid); // Do home grid first.
for (int shell = 1; true; shell++) // Now shell outwards from home.
{
Start = xIndex - shell; if (Start < 0)
{
Start = 0; // Thanks to Matt Gessner
}
End = xIndex + shell + 1; if (End > NumXcoords)
{
End = NumXcoords;
}
// Do top row.
if (!TopDone)
{
Row = yIndex + shell;
if (Row >= NumYcoords)
{
TopDone = true;
}
else
{
TestDist = Grid.y(Row) - Grid.y(yIndex);
TestDist = TestDist * TestDist;
if (((NoFound > 0) && ((TestDist > ClosestSquared * ScanStopRatio)) ||
(TestDist > xyStopDistSq)))
{
TopDone = true;
}
else
{
for (i = Start; i < End; i++)
{
ScanOneGrid(i, Row, ref Data, ref Grid);
}
}
}
}
// Do bottom row.
if (!BottomDone)
{
Row = yIndex - shell;
if (Row < 0)
{
BottomDone = true;
}
else
{
TestDist = Grid.y(yIndex) - Grid.y(Row);
TestDist = TestDist * TestDist;
if (((NoFound > 0) && ((TestDist > ClosestSquared * ScanStopRatio)) ||
(TestDist > xyStopDistSq)))
{
BottomDone = true;
}
else
{
for (i = Start; i < End; i++)
{
ScanOneGrid(i, Row, ref Data, ref Grid);
}
}
}
}
Start = yIndex - shell + 1; if (Start < 0)
{
Start = 0; // Thanks to Matt Gessner
}
End = yIndex + shell; if (End > NumYcoords)
{
End = NumYcoords;
}
// Do left column.
if (!LeftDone)
{
Column = xIndex - shell;
if (Column < 0)
{
LeftDone = true;
}
else
{
TestDist = Grid.x(xIndex) - Grid.x(Column);
TestDist = TestDist * TestDist;
if (((NoFound > 0) && ((TestDist > ClosestSquared * ScanStopRatio)) ||
(TestDist > xyStopDistSq)))
{
LeftDone = true;
}
else
{
for (i = Start; i < End; i++)
{
ScanOneGrid(Column, i, ref Data, ref Grid);
}
}
}
}
// Do right column.
if (!RightDone)
{
Column = xIndex + shell;
if (Column >= NumXcoords)
{
RightDone = true;
}
else
{
TestDist = Grid.x(Column) - Grid.x(xIndex);
TestDist = TestDist * TestDist;
if (((NoFound > 0) && ((TestDist > ClosestSquared * ScanStopRatio)) ||
(TestDist > xyStopDistSq)))
{
RightDone = true;
}
else
{
for (i = Start; i < End; i++)
{
ScanOneGrid(Column, i, ref Data, ref Grid);
}
}
}
}
if (TopDone && BottomDone && LeftDone && RightDone)
{
TotalShells += shell; break;
}
}
}
