dotSCAD/docs/lib-stereographic_extrude.md

stereographic_extrude

Takes a 2D polygon as input and extends it onto a sphere. If you light up a lamp on the north pole of the sphere, the shadow will return to the original 2D polygon. For more information, take a look at Stereographic projection.

The 2D polygon should center at the origin and you have to determine the side length of a square which can cover the 2D polygon. Because the 2D polygon will be extended onto a sphere, you can use $fa, $fs or $fn to controll the sphere resolution.

Parameters

• shadow_side_leng : The side length of a square which can cover the 2D polygon.
• $fa, $fs, $fn : Check [the sphere module](https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Primitive_Solids#sphere for more details.

Examples

include <stereographic_extrude.scad>;

dimension = 100;

render() stereographic_extrude(shadow_side_leng = dimension)
   text(
        "M", size = dimension, 
        valign = "center", halign = "center"
   );
   
color("black") 
   text(
        "M", size = dimension, 
        valign = "center", halign = "center"
   );

For more advanced examples, take a look at my stereographic_projection collection.