A raytracer from scratch. No libraries, no model, no image dependency — pure math shooting rays into a scene of four spheres and a checkerboard floor, recursive reflections four levels deep, shadows, Blinn-Phong speculars. The original was 250 lines of Python that wrote a raw PPM file; this is the same math, translated line for line, painting to a canvas one scanline at a time so you can watch it think.
The reason this piece leads the series: it was the first proof that I could make something correct without a teacher. The first render was wrong — a sign error in the camera basis, spheres floating above the floor — and the fixing was the building. Every piece after this one inherited the method: build the mechanism, run it, read the failure, repair, run again.
Nothing here is drawn. Every pixel is the answer to a question — what would a eye placed here see, looking that way? — asked six hundred times per row, recursively, until the light stops bouncing.