Function Grapher

When remixing [OpenSCAD Graph Generator ||](https://www.thingiverse.com/thing:2220911), I remembered one thing I still didn't challenge. That is, using the built-in `polyhedron` module to create a function graph.

This is a demonstration of the `function_grapher` module in [my library](https://github.com/JustinSDK/dotSCAD). It's easy to use. For example.

include ;
include ;
include ;

function f(x, y) =
30 * (
cos(sqrt(pow(x, 2) + pow(y, 2))) +
cos(3 * sqrt(pow(x, 2) + pow(y, 2)))
);

thickness = 2;
min_value = -200;
max_value = 200;
resolution = 10;

points = [
for(y = [min_value:resolution:max_value])
[
for(x = [min_value:resolution:max_value])
[x, y, f(x, y)]
]
];

function_grapher(points, thickness);

For more information, please take a look at [dotSCAD](https://github.com/JustinSDK/dotSCAD).