add archimedean_text_sphere

examples/archimedean_text_sphere.scad

@@ -0,0 +1,35 @@
+use <experimental/bauer_spiral.scad>;
+
+txt = "3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798609437027705392171762931767523846748184676694051";
+
+radius = 20;
+font_name = "Liberation Sans:style=Bold";
+font_size = 2.5;
+$fn = 48;
+
+archimedean_text_sphere(radius, font_name, font_size);
+
+module archimedean_text_sphere(radius, font_name, font_size) {
+    n = len(txt);
+    pts = bauer_spiral(n, radius);
+
+    render() 
+    sphere(radius * 0.9);
+
+    for(i = [0:n - 1]) {
+        x = pts[i][0];
+        y = pts[i][1];
+        z = pts[i][2];
+        ya = atan2(z, sqrt(x * x + y * y));
+        za = atan2(y, x);
+
+        render() 
+        translate(pts[i])
+        rotate([0, -ya, za])
+        rotate([90, 0, -90])
+        linear_extrude(radius * 0.125, scale = 1.15)
+        mirror([-1, 0, 0])
+            text(txt[i], size = font_size, font = font_name, valign = "center", halign = "center");
+    }
+}
+