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> Spheres can also wind up being more finnicky with precision but are rarely used as primitives to trace against in production renderers. I've never heard this

• dahart 7y ago
  It's because tracing a sphere is quadratic equation solve. The guy in the video, Eric Haines, published an article about how to improve sphere tracing precision. It's in the freely available Ray Tracing Gems book. https://link.springer.com/content/pdf/10.1007%2F978-1-4842-4427-2_7.pdf https://link.springer.com/content/pdf/10.1007%2F978-1-4842-4...
• daniel-thompson 7y ago
  Spheres are the "hello world" shape of ray tracing, but are generally not used for production renderers for the following reasons: Spheres are not that interesting to render, because hardly anything in the real world is a perfect sphere; and determining a ray-sphere intersection point requires solving at least one quadratic equation, which requires a square root, which is slow Triangle meshes are better choices for the same reasons: they can be used to model arbitrarily complex shapes, and it's faster to compute ray-triangle intersections.