A 2D slice through an SDF scene. Every circle is one step, and its radius is the distance field at that point.
Drag the white dot to move the ray origin, the small ring to aim it. The thin strip underneath is the 1-D image a camera at that origin would render.
What to notice. The circles are tangent: each step lands exactly on the edge of the previous circle, because the field promised nothing was nearer than that. Aim the ray so it grazes a shape and the steps crawl — that is why silhouettes cost the most. Change scene and watch the boolean appear in the bands themselves, not just in the outline: subtraction really does put a negative region back outside. Then push step × above 1 on the thin-walls scene and the ray punches straight through solid geometry — exactly the artefact a non-exact distance field gives you for free.
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