public void SuperSampleRangeList_Single()
{
var ssRanges = new SuperSampleRangeList();
ssRanges.Populate(new[]
{
new EdgeIntersectionRange {
FromX = 6, Width = 0
}
});
Assert.AreEqual(1, ssRanges.Count);
Assert.AreEqual(6, ssRanges[0].FromX);
Assert.AreEqual(0, ssRanges[0].Width);
}
public void SuperSampleRangeList_Adjacent_NoDistance()
{
var ssRanges = new SuperSampleRangeList();
ssRanges.Populate(new[]
{
new EdgeIntersectionRange {
FromX = 5, Width = 10
},
new EdgeIntersectionRange {
FromX = 14, Width = 10
}
});
Assert.AreEqual(1, ssRanges.Count);
Assert.AreEqual(5, ssRanges[0].FromX);
Assert.AreEqual(19, ssRanges[0].Width);
}
public void SuperSampleRangeList_Containing()
{
var ssRanges = new SuperSampleRangeList();
ssRanges.Populate(new[]
{
new EdgeIntersectionRange {
FromX = 10, Width = 20
},
new EdgeIntersectionRange {
FromX = 15, Width = 5
}
});
Assert.AreEqual(1, ssRanges.Count);
Assert.AreEqual(10, ssRanges[0].FromX);
Assert.AreEqual(20, ssRanges[0].Width);
}
public void SuperSampleRangeList_Overlapping()
{
var ssRanges = new SuperSampleRangeList();
ssRanges.Populate(new[]
{
new EdgeIntersectionRange {
FromX = 5, Width = 10
},
new EdgeIntersectionRange {
FromX = 10, Width = 10
}
});
Assert.AreEqual(1, ssRanges.Count);
Assert.AreEqual(5, ssRanges[0].FromX);
Assert.AreEqual(15, ssRanges[0].Width);
}
private ColorRange[] Render()
{
this.edges.Sort();
var writer = new BitmapWriter(BackgroundColor, width, height);
var superSampleBuffer = new SuperSampleBuffer(width);
var layers = new LayerManager[SuperSampling.SamplesPerPixelY];
var superSampleRanges = new SuperSampleRangeList();
// Keeps track of how many of the subpixellayers that are used for
// the currently rendered scanline. Until a range requiring supersampling
// is encountered only a single layer is needed.
var usedLayers = 0;
var color = default(Color);
var intersections = new IntersectionList();
// Create a layer manager for every subpixel scanline
for (var i = 0; i < layers.Length; i++)
{
layers[i] = new LayerManager();
}
for (var ey = 0; ey < height; ey++)
{
var ranges = this.edges[ey];
if (ranges.Count == 0)
{
writer.Skip(width);
continue;
}
for (var i = 0; i < usedLayers; i++)
{
layers[i].Clear();
}
usedLayers = 1;
superSampleRanges.Populate(ranges);
writer.Skip(superSampleRanges[0].FromX);
for (var rangeIndex = 0; rangeIndex < superSampleRanges.Count; rangeIndex++)
{
ref var superSampleRange = ref superSampleRanges[rangeIndex];
// If there is exactly one edge in the supersample range, and it is crossing
// the entire scanline, we can perform the antialiasing by integrating the
// edge function.
if (superSampleRange.Count == 1 && (
superSampleRange[0].From.Y <= ey && superSampleRange[0].To.Y >= ey + 1 ||
superSampleRange[0].From.Y >= ey + 1 && superSampleRange[0].To.Y <= ey
))
{
var edge = superSampleRange[0];
// Determine the lower and upper x value where the edge
// intersects the scanline.
var xey = edge.Intersection(ey);
var xey1 = edge.Intersection(ey + 1);
var x0 = Math.Min(xey, xey1);
var x1 = Math.Max(xey, xey1);
var width = x1 - x0;
// Compute the average color of all subpixel layers before
// and after the edge intersection.
var fromColorAverage = new AverageColor();
var toColorAverage = new AverageColor();
for (var sy = 0; sy < usedLayers; sy++)
{
var subScanlineLayers = layers[sy];
fromColorAverage.Add(subScanlineLayers.CurrentColor);
toColorAverage.Add(subScanlineLayers.Add(edge));
}
var fromColor = fromColorAverage.Color;
color = toColorAverage.Color;
// Render pixels
for (var x = superSampleRange.FromX; x < superSampleRange.ToXExcl; x++)
{
if (x0 >= x + 1)
{
// Pixel not covered
writer.Write(fromColor);
continue;
}
if (x1 <= x)
{
// Pixel fully covered
writer.Write(color);
continue;
}
// toColor coverage in the range [0.0, 1.0]
// Initialize to the fully covered range of the pixel.
var coverage = x1 < x + 1 ? x + 1 - x1 : 0;
// Compute integral for non-vertical edges
if (width > 0.001f)
{
// Range to integrate
var integralFrom = Math.Max(x0, x);
var integralTo = Math.Min(x1, x + 1);
coverage +=
(
(integralTo * integralTo - integralFrom * integralFrom) / 2 +
x0 * (integralFrom - integralTo)
) / width;
}
writer.Write(Color.Mix(fromColor, color, coverage));
}
} // /simplified antialiasing
else
{
// There are more than a single intersecting edge in this range.
// Use super sampling to render the pixels.
intersections.Initialize(ranges.Count);
var y = ey + SuperSampling.SampleHeight / 2;
// Ensure all subpixel layers are initialized
while (usedLayers < SuperSampling.SamplesPerPixelY)
{
layers[0].CopyTo(layers[usedLayers]);
usedLayers++;
}
// Average color of the pixels following the current supersample range.
var forwardColorAverage = new AverageColor();
for (var sy = 0; sy < SuperSampling.SamplesPerPixelY; sy++, y += SuperSampling.SampleHeight)
{
var subScanlineLayers = layers[sy];
color = subScanlineLayers.CurrentColor;
superSampleRange.GetIntersections(ref intersections, y);
for (var i = 0; i < intersections.Count; i++)
{
ref var intersection = ref intersections[i];
superSampleBuffer.Add(color, intersection.X - superSampleRange.FromX);
color = subScanlineLayers.Add(intersection.Edge);
}
// Write an extra pixel that will contain the color that
// will be forwarded until the next supersample range.
superSampleBuffer.Add(color, superSampleRange.Width);
superSampleBuffer.Rewind();
forwardColorAverage.Add(color);
} // /subpixel
// Get color to be forwarded
color = forwardColorAverage.Color;
// Blend subpixels
superSampleBuffer.WriteTo(ref writer, superSampleRange.Width);
superSampleBuffer.Clear();
} // /supersampling
// Forward last color
if (rangeIndex + 1 < superSampleRanges.Count)
{
var nextRangeX = superSampleRanges[rangeIndex + 1].FromX;
writer.Write(color, nextRangeX - superSampleRange.ToXExcl);
}
else
{
writer.Write(color, width - superSampleRange.ToXExcl);
}
} // /range
