//************************************************************
// W e i g h t e d A v e r a g e
//************************************************************
static float WeightedAverage(ref ScatteredData Data)
// function calculates the weighted average value for the
// specified grid point. The needed data is all in PointInOctant
// and PointDistSquared.
{
float SumSquared = 0.0f;
float SumWeights = 0.0f;
for (int i = 0; i < 8; i++)
{
long Point = PointInOctant[i];
if (Point > -1)
{
float DistanceSquared = PointDistSquared[i];
// Check for point right on a grid intersection.
if (DistanceSquared == 0.0)
{
return(Data.Z[Point]);
}
SumSquared += 1.0f / DistanceSquared;
SumWeights += (1.0f / DistanceSquared) * Data.Z[Point];
}
}
return(SumWeights / SumSquared);
}
//***************************************************************
// 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))
{
;
}
}
//****************************************************************
// P u t I n O c t a n t
//****************************************************************
static void PutInOctant(float x, float y, ref ScatteredData Data, long DataIndex)
{
float Xdistance = Data.X[DataIndex] - x;
float Ydistance = Data.Y[DataIndex] - y;
// Select the octant the data point is in. They are labeled:
// 31
// 2 0
// 6 4
// 75
int Octant = 0;
if (Ydistance < 0.0)
{
Octant = 4;
}
if (Xdistance < 0.0)
{
Octant += 2;
}
if (Math.Abs(Xdistance) < Math.Abs(Ydistance))
{
Octant += 1;
}
// and get the distance squared and save that information
// for that Octant iff this is the first point found or closer than
// the point previously saved for that octant.
float DistSquared = Xdistance * Xdistance + Ydistance * Ydistance;
if (NoFound == 0)
{
ClosestSquared = DistSquared;
}
if (DistSquared < ClosestSquared)
{
ClosestSquared = DistSquared;
}
NoFound++;
if (PointInOctant[Octant] == -1 ||
DistSquared < PointDistSquared[Octant])
{
PointInOctant[Octant] = DataIndex;
PointDistSquared[Octant] = DistSquared;
}
}
//**************************************************************
// 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);
}
// ***************************************************************
// 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;
}
}
}
