Developer Discovers Shared Sampling Function Breaks Diffuse Rendering When Changing Aperture Shape

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A developer building a raytracer from scratch found that experimenting with a hexagonal camera aperture inadvertently corrupted all diffuse surfaces in the renderer. The root cause was a single shared function, SampleUnitDisk, used by both the camera lens sampler and the diffuse surface lighting model. Changing the disk-sampling logic to a hexagonal boundary affected not just bokeh shape but also Malley's method, which relies on uniform disk sampling to correctly simulate diffuse light scattering. The developer caught the bug by manually reviewing their own code, but acknowledged this was not a reliable safeguard. The incident highlights the risk of coupling physically distinct rendering systems to a single shared primitive.

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