add lemniscate_curve

src/lemniscate_curve.scad

@@ -0,0 +1,45 @@
+/*
+use <lemniscate_curve.scad>;
+use <path_extrude.scad>;
+use <shape_star.scad>;
+
+shape_pts = [
+    [3, -1.5],
+    [3, 1.5], 
+    [2, 1.5],
+    [2, 0.5],
+    [-2, 0.5],
+    [-2, 1.5],    
+    [-3, 1.5],    
+	[-3, -1.5],
+    [-2, -1.5],
+	[-2, -0.5],
+	[2, -0.5],
+	[2, -1.5]
+];
+
+path_pts = lemniscate_curve(2, 1, .75, .075) * 20;
+path_extrude(
+    shape_pts, 
+	concat(path_pts, [path_pts[0]]), 
+	method = "EULER_ANGLE"
+);
+
+path_pts2 = lemniscate_curve(2, 1, .75, .2) * 20;
+translate([0, 30, 0])
+    path_extrude(shape_star() * 3, 
+	concat(path_pts2, [path_pts2[0]]), 
+	method = "EULER_ANGLE"
+);
+
+
+*/
+function lemniscate_curve(t_step, a = 1, b = 1, c = 1) = 
+    [
+	    for(t = [0:t_step:360 - t_step])
+		let(
+		    sint = sin(t),
+			cost = cos(t)
+		)
+		[a * sint, b * sint * cost, c * cost]
+	];