public void AddSample(Point2 <float> posFilm, Spectrum L, float sampleWeight = 1.0f)
{
// Determine the bounds of the pixels that are affected by the new sample
var posFilmDiscrete = posFilm - new Vector2 <float>(0.5f, 0.5f);
var p0 = (posFilmDiscrete - filter.Radius).Ceiling().ToInt();
var p1 = (posFilmDiscrete + filter.Radius).Floor().ToInt() + Point2 <int> .One;
p0 = Point2 <int> .Max(p0, pixelBounds.Min);
p1 = Point2 <int> .Min(p1, pixelBounds.Max);
// Compute offsets into the filter weight table for each affected pixel
var filterTableSize = (int)Math.Sqrt(filterTable.Length);
var ifx = new int[p1.X - p0.X];
for (var x = p0.X; x < p1.X; ++x)
{
var fx = Math.Abs((x - posFilmDiscrete.X) * filter.InvRadius.X * filterTableSize);
ifx[x - p0.X] = (int)Math.Min(Math.Floor(fx), filterTableSize - 1);
}
var ify = new int[p1.Y - p0.Y];
for (var y = p0.Y; y < p1.Y; ++y)
{
var fy = Math.Abs((y - posFilmDiscrete.Y) * filter.InvRadius.Y * filterTableSize);
ify[y - p0.Y] = (int)Math.Min(Math.Floor(fy), filterTableSize - 1);
}
// Add the effective contribution for each pixel
for (var y = p0.Y; y < p1.Y; ++y)
{
for (var x = p0.X; x < p1.X; ++x)
{
// Evaluate the filter value at the current pixel
var offset = ify[y - p0.Y] * filterTableSize + ifx[x - p0.X];
var filterWeight = filterTable[offset];
//
var tileOffset = (y - pixelBounds.Min.Y) * (int)pixelBounds.Width() + (x - pixelBounds.Min.X);
pixels[tileOffset].contribSum += L * filterWeight * sampleWeight;
pixels[tileOffset].filterWeightSum += filterWeight;
}
}
}
public FilmTile(Bounds2 <int> pixelBounds, Filter filter, float[] filterTable)
{
this.pixelBounds = pixelBounds;
this.filter = filter;
this.filterTable = filterTable;
pixels = new Pixel[(int)pixelBounds.Width() * (int)pixelBounds.Height()];
}