Logging material (Spot diagrams)

[mattngc]

Using a plane primitive, create a new material which logs every intersections but passes rays through unaffected. Record some ray properties, maybe colour by wavelength?

This could be implemented as a decorator with an interstitial logging material that wraps an existing material and logs all ray interactions with the material.

[mattngc]

Might be interesting in lens system designs to colour a material surface by ray density.

[CnlPepper]

A cython version of this, and a decorator to apply it.

class LoggingMaterial(Material):

def __init__(self, material, log):
    super().__init__()
    self.material = material
    self.log = log
    self.importance = material.importance

def evaluate_surface(self, world, ray, primitive, hit_point, exiting,
                     inside_point, outside_point, normal,
                     world_to_primitive, primitive_to_world):

    self.log.append(hit_point.transform(primitive_to_world))

    return self.material.evaluate_surface(
        world, ray, primitive, hit_point, exiting,
        inside_point, outside_point, normal,
        world_to_primitive, primitive_to_world
    )

def evaluate_volume(self, spectrum, world, ray, primitive, start_point, end_point,
                    world_to_primitive, primitive_to_world):

    return self.material.evaluate_volume(
        spectrum, world, ray, primitive, start_point, end_point,
        world_to_primitive, primitive_to_world
    )

Would probably want to collect more information than just the hit point, e.g. spectral range of ray etc... Could be options on the logging material.