Signed distance, negative inside the solid, any shape.
required
epsilon
float
Interface half-width in the same units as distance.
required
profile
str
"smootherstep" – Perlin’s quintic blend, exactly 1 below -epsilon and exactly 0 above +epsilon, with both first and second derivatives vanishing at the join. "smoothstep" – the cubic Hermite blend, same support but only C1. "sigmoid" – sigmoid(-distance/epsilon), which never reaches either end; see this module’s docstring for why that is a poor choice for a penalisation field and a fine one for a volume integral.