Shader node providing 2D and 3D SDF functions.
Based on Inigo Quilez SDF work here: https://www.iquilezles.org/www/articles/distfunctions/distfunctions.htm
Notes: Some functions have been normalised to 1.0 size.
Tips: Combining SDF outputs using maths node min max functions provides a way to create unions, subtractions and intersections.
Rounding = moves the threshold of the sdf function. This is equivalent of subtracting/adding values.
Thickness = this creates an edge at the threshold and creates inset effect.
Edges/Radius: Used with Star function only.
Bugs: Issue with texture mapping in cycles. Not sure if this is a bug in this code or elsewhere.