add in_shape

src/__private__/__edges_from.scad

@@ -0,0 +1,7 @@
+function __edges_from(pts) = 
+    let(leng = len(pts))
+    concat(
+        [for(i = [0:leng - 2]) [pts[i], pts[i + 1]]], 
+        [[pts[len(pts) - 1], pts[0]]]
+    );
+    

src/in_shape.scad

@@ -0,0 +1,56 @@
+include <__private__/__edges_from.scad>;
+
+function _in_shape_in_line_equation(edge, pt) = 
+    let(
+        x1 = edge[0][0],
+        y1 = edge[0][1],
+        x2 = edge[1][0],
+        y2 = edge[1][1],
+        a = (y2 - y1) / (x2 - x1),
+        b = y1 - a * x1
+    )
+    (pt[1] == a * pt[0] + b);
+    
+function _in_shape_in_edge(edge, pt) =
+    let(
+        maxx = max([edge[0][0], edge[1][0]]),
+        minx = min([edge[0][0], edge[1][0]]),
+        maxy = max([edge[0][1], edge[1][1]]),
+        miny = min([edge[0][1], edge[1][1]]),
+        vt = edge[1] - edge[0]
+    )
+    pt[0] >= minx && pt[0] <= maxx && pt[1] >= miny && pt[1] <= maxy &&
+    (vt[0] == 0 ? (pt[0] == edge[0][0]) : _in_shape_in_line_equation(edge, pt));
+
+function _in_shape_in_any_edges_sub(edges, leng, pt, i) = 
+    leng == i ? false : (
+        _in_shape_in_edge(edges[i], pt) ? true : _in_shape_in_any_edges_sub(edges, leng, pt, i + 1)
+    );
+
+function _in_shape_in_any_edges(edges, pt) = _in_shape_in_any_edges_sub(edges, len(edges), pt, 0);
+    
+
+function _in_shape_interpolate_x(y, p1, p2) = 
+    p1[1] == p2[1] ? p1[0] : (
+        p1[0] + (p2[0] - p1[0]) * (y - p1[1]) / (p2[1] - p1[1])
+    );
+    
+function _in_shape_does_pt_cross(pts, i, j, pt) = 
+    ((pts[i][1] > pt[1]) != (pts[j][1] > pt[1])) &&
+    (pt[0] < _in_shape_interpolate_x(pt[1], pts[i], pts[j]));
+    
+
+function _in_shape_sub(shapt_pts, leng, pt, cond, i, j) =
+    j == leng ? cond : (
+        _in_shape_does_pt_cross(shapt_pts, i, j, pt) ? 
+            _in_shape_sub(shapt_pts, leng, pt, !cond, j, j + 1) :
+            _in_shape_sub(shapt_pts, leng, pt, cond, j, j + 1)
+    );
+ 
+function in_shape(shapt_pts, pt, include_edge = false) = 
+    let(
+        leng = len(shapt_pts),
+        edges = __edges_from(points)
+    )
+    _in_shape_in_any_edges(edges, pt) ? include_edge : 
+    _in_shape_sub(shapt_pts, leng, pt, false, leng - 1, 0);