Bonus Chapter: Rendering Soft Shadows

uvec and vvec are associated to the area light edges, you can set them to any direction and the area light becomes oriented accordingly.

ascotti Jamis Thanks Got! I was thinking in 2D and working in 2D. It now makes sense. Because I was not thinking correctly when creating an area light I was dividing the X and Z coordinate to create uvec and vvec by usteps and vsteps. Instead of dividing the whole vector by the steps. Doooh! Then when I was working on the scenarios using Y coordinate I was confused.

there are multiple questions, I will give feedback and add some questions

Your first question I don't have enough information, but I was wondering if your sequencer you built for testing is a ring implementation? Does it start over if it reaches the end of the sequence?

For Scenario Outline: lighting() samples are you looping through the samples of each point in the area light? Is the light_vector using the light_position of the current instance of the cell from the loop of cells in the area light? I will share my lighting function, but keep in mind I pass the computation as a parameter instead of the individual properties of the computations. So you might be wondering why I'm not passing many parameters to the function. Also using c#.

Lighting

You mentioned that pattern_at_shape uses light.position but I don't see that in the code I have written. What I see is that pattern_at_shape translates a word location to a local location, but no dependency on light.position. Can you elaborate on this?

Regarding the jitter true/false, this will allow for the area light to have jitter or not. How I implemented this was to build off the concept of the sequence used in testing. Testing uses a deterministic ring sequence. I also built a non-deterministic sequence which returns a random number. The test ask for a sequence of numbers, sequence(0.1, 0.5, 1.0). If jitter is false then I use a sequence with only one number, .5. Which mean .5 is returned ever time Next() is called. If jitter is true, I assign the attribute/property jitter_by with a non-deterministic sequence that returns a random number.

NoneDeterministicSequence

DeterministicSequence

C#

If (jitter)
{
   areaLight.JitterBy = new NoneDeterministicSequence();
}
else
{
   areaLight.JitterBy = new DeterministicSequence(0.5);
}
Here is a sample of the outcome with my implementation

I reviewed some code, but nothing sticks out. Have you tried either debugging and stepping through code to see if the expected values are present, or output trace information?

The math would indicate that there are 4 samples and the IsShadow should be true for 2 iteration of the 4 which would give you the 0.5 results. I'm going to assume that 3 of the iterations not returning true giving you only 1 IsShadow true which will then give you 0.25 as a result.

Below are the values of the IntensityAt function, which you might also want to evaluate the PointOnLight function making sure you are getting the correct jitter values.