Ray marching

The technique dates back to at least the 1980s; the1989 paper "Hypertexture"[1] by Ken Perlin contains an early example of a ray marching method.

The SDF is evaluated for each iteration in order to be able take as large steps as possible without missing any part of the surface.

As powerful GPU hardware became more widely available, this method was popularized by the demoscene and Inigo Quilez,[citation needed] co-creator of Shadertoy.

Strengths of SDF ray marching are, for example, when morphing shapes, approximating soft shadows, repetition of geometry, and algorithmically defined scenes.

[4] A similar technique to sphere-assisted ray marching, the use of cubes and taxicab distance can be used to render voxel volumes.