public float DensityAtLocation(MSPoint point)
{
float density = 0.0f;
foreach (MSParticle particle in ParticleList)
{
float distanceToParticleSqr = (particle.Position - point).LengthSqr();
if (distanceToParticleSqr <= particle.RadiusSqr)
{
density += 1.0f;
}
}
return(density);
}
public static MSPoint max(MSPoint p1, MSPoint p2)
{
return(new MSPoint(Math.Max(p1.X, p2.X), Math.Max(p1.Y, p2.Y)));
}
public MSPoint(MSPoint point)
{
X = point.X;
Y = point.Y;
}
public MSLine(MSPoint start, MSPoint end)
{
Start = start;
End = end;
}
public MSLine()
{
Start = new MSPoint(0.0f);
End = new MSPoint(0.0f);
}
public void GenerateLines(MSParticleField particleField)
{
ResetData();
if (particleField.ParticleList.Count <= 0)
{
return;
}
min = new MSPoint(float.MaxValue);
max = new MSPoint(float.MinValue);
MSPoint particleRadius = new MSPoint(0.0f);
// find the extents of the area we need to surround with lines (include the particle radius)
foreach (MSParticle particle in particleField.ParticleList)
{
particleRadius.X = particle.Radius;
particleRadius.Y = particle.Radius;
min = MSPoint.min(particle.Position - particleRadius, min);
max = MSPoint.max(particle.Position + particleRadius, max);
}
// round up/down to the nearest cell size, then expand out another cell - incase the min/max is already aligned to the grid
min.X = min.X - (min.X % cellSize) - cellSize;
min.Y = min.Y - (min.Y % cellSize) - cellSize;
max.X = max.X + (cellSize - (max.X % cellSize)) + cellSize;
max.Y = max.Y + (cellSize - (max.Y % cellSize)) + cellSize;
int xSteps = (int)((max.X - min.X) / cellSize);
int ySteps = (int)((max.Y - min.Y) / cellSize);
// sample the field density at each square's corner
densityArray = new float[xSteps, ySteps];
MSPoint testPoint = new MSPoint(0.0f);
for (int x = 0; x < xSteps; ++x)
{
for (int y = 0; y < ySteps; ++y)
{
testPoint.X = min.X + (float)x * cellSize;
testPoint.Y = min.Y + (float)y * cellSize;
densityArray[x, y] = particleField.DensityAtLocation(testPoint);
}
}
// for each square - look up in the connections table what lines to generate and add them
for (int x = 0; x < xSteps - 1; ++x)
{
for (int y = 0; y < ySteps - 1; ++y)
{
float upperLeft = densityArray[x, y];
float upperRight = densityArray[x + 1, y];
float lowerLeft = densityArray[x, y + 1];
float lowerRight = densityArray[x + 1, y + 1];
int tableIndex = 0;
tableIndex |= upperLeft >= DensityThreshold ? 8 : 0;
tableIndex |= upperRight >= DensityThreshold ? 4 : 0;
tableIndex |= lowerLeft >= DensityThreshold ? 1 : 0;
tableIndex |= lowerRight >= DensityThreshold ? 2 : 0;
List <SquareSide> edges = edgeTable[tableIndex];
foreach (SquareSide edge in edges)
{
int index = 0;
MSPoint[] line = new MSPoint[2];
if ((edge & SquareSide.eTop) > 0)
{
float interpolationFactor = (DensityThreshold - upperLeft) / (upperRight - upperLeft);
line[index] = new MSPoint(
min.X + (float)x * cellSize + cellSize * interpolationFactor
, min.Y + (float)y * cellSize);
++index;
}
if ((edge & SquareSide.eBottom) > 0)
{
float interpolationFactor = (DensityThreshold - lowerLeft) / (lowerRight - lowerLeft);
line[index] = new MSPoint(
min.X + (float)x * cellSize + cellSize * interpolationFactor
, min.Y + (float)(y + 1) * cellSize);
++index;
}
if ((edge & SquareSide.eLeft) > 0)
{
float interpolationFactor = (DensityThreshold - upperLeft) / (lowerLeft - upperLeft);
line[index] = new MSPoint(
min.X + (float)x * cellSize
, min.Y + (float)y * cellSize + cellSize * interpolationFactor);
++index;
}
if ((edge & SquareSide.eRight) > 0)
{
float interpolationFactor = (DensityThreshold - upperRight) / (lowerRight - upperRight);
line[index] = new MSPoint(
min.X + (float)(x + 1) * cellSize
, min.Y + (float)y * cellSize + cellSize * interpolationFactor);
++index;
}
if (index == 2)
{
generatedLines.Add(new MSLine(line[0], line[1]));
}
}
}
}
}
