Macro surface 

macro_rules! surface {
    (file=$file:expr, center=$center:expr, invert=$invert:expr, convexity=$convexity:expr) => { ... };
    ($file:expr) => { ... };
}

Loads a height map from a file.

#params

file: The path to the file to load.

center: Whether to center object or leave in first octant.

invert: Whether to invert the data.

convexity: The number of outside faces a ray could pass through when intersecting the object. Preview only.

expansion: A Scad struct literal.

#patterns

surface!(‘file: &str’);

surface!(file=‘file: &str’, center=‘center: bool’, invert=‘invert: bool’, convexity=‘convexity: u64’);