public void BorderHandling_IsCorrect()
{
var weights = new float[] { 1, 1, 2, 2 };
var dist = new PiecewiseConstant(weights);
var(idx, rel) = dist.Sample(0.0f);
Assert.Equal(0, idx);
Assert.Equal(0.0f, rel, 6);
(idx, rel) = dist.Sample(1.0f);
Assert.Equal(3, idx);
Assert.Equal(1.0f, rel, 6);
(idx, rel) = dist.Sample(0.999f);
Assert.Equal(3, idx);
Assert.Equal(0.999f, rel, 2);
(idx, rel) = dist.Sample(0.0001f);
Assert.Equal(0, idx);
Assert.Equal(0.0001f * 6.0f, rel, 6);
}
public void AsymptoticDistribution()
{
var weights = new float[] { 1, 1, 2, 2 };
var dist = new PiecewiseConstant(weights);
var counters = new float[] { 0, 0, 0, 0 };
int numSteps = 100;
for (float u = 0.0f; u < 1.0f; u += 1.0f / numSteps)
{
counters[dist.Sample(u).Item1] += 6.0f / numSteps;
}
Assert.Equal(1.0f, counters[0], 1);
Assert.Equal(1.0f, counters[1], 1);
Assert.Equal(2.0f, counters[2], 1);
Assert.Equal(2.0f, counters[3], 1);
}
public void ShouldBeUniformWithin()
{
var weights = new float[] { 1, 1, 2, 2 };
var dist = new PiecewiseConstant(weights);
int numSteps = 1000;
var counters = new float[numSteps];
for (float u = 0.0f; u < 1.0f; u += 1.0f / numSteps)
{
var(_, pos) = dist.Sample(u);
counters[(int)Math.Max(Math.Min(pos * numSteps, numSteps), 0)] += 1.0f / numSteps;
}
int nonzero = 0;
foreach (float c in counters)
{
nonzero += c > 0 ? 1 : 0;
}
Assert.True(nonzero > numSteps * 0.8);
}
public void Singularity_ShouldBeSampledExclusively()
{
var weights = new float[] { 283, 0, 0, 0, 0 };
var dist = new PiecewiseConstant(weights);
var(idx, rel) = dist.Sample(0.0f);
Assert.Equal(0, idx);
(idx, rel) = dist.Sample(1.0f);
Assert.Equal(0, idx);
(idx, rel) = dist.Sample(0.999f);
Assert.Equal(0, idx);
(idx, rel) = dist.Sample(0.0001f);
Assert.Equal(0, idx);
(idx, rel) = dist.Sample(0.1f);
Assert.Equal(0, idx);
(idx, rel) = dist.Sample(0.8f);
Assert.Equal(0, idx);
}