From e0256a0925b9f14e74fe518ad40db280fc8a31ef Mon Sep 17 00:00:00 2001
From: Justin Lin <caterpillar@openhome.cc>
Date: Tue, 28 May 2019 14:28:53 +0800
Subject: [PATCH] refactor

---
 src/__private__/__line_intersection.scad | 12 ++++++++++++
 src/bijection_offset.scad                | 18 +++---------------
 2 files changed, 15 insertions(+), 15 deletions(-)
 create mode 100644 src/__private__/__line_intersection.scad

diff --git a/src/__private__/__line_intersection.scad b/src/__private__/__line_intersection.scad
new file mode 100644
index 00000000..9d958107
--- /dev/null
+++ b/src/__private__/__line_intersection.scad
@@ -0,0 +1,12 @@
+function __line_intersection(line_pts1, line_pts2) = 
+    let(
+        a1 = line_pts1[0],
+        a2 = line_pts1[1],
+        b1 = line_pts2[0],
+        b2 = line_pts2[1],
+        a = a2 - a1, 
+        b = b2 - b1, 
+        s = b1 - a1
+    )
+    cross(a, b) == 0 ? [] :  // they are parallel or conincident edges
+        a1 + a * cross(s, b) / cross(a, b);
\ No newline at end of file
diff --git a/src/bijection_offset.scad b/src/bijection_offset.scad
index 7a5b39f7..9f1be251 100644
--- a/src/bijection_offset.scad
+++ b/src/bijection_offset.scad
@@ -9,6 +9,7 @@
 **/
 
 include <__private__/__edges_from.scad>;
+include <__private__/__line_intersection.scad>;
     
 function _bijection_inward_edge_normal(edge) =  
     let(
@@ -41,25 +42,12 @@ function _bijection__bijection_offset_edges(edges, d) =
         _bijection_offset_edge(edge, dx, dy)
     ];
 
-function _bijection__bijection__bijection_offset_edges_intersection(edge1, edge2) = 
-    let(
-        a1 = edge1[0],
-        a2 = edge1[1],
-        b1 = edge2[0],
-        b2 = edge2[1],
-        a = a2 - a1, 
-        b = b2 - b1, 
-        s = b1 - a1
-    )
-    cross(a, b) == 0 ? [] : // they are parallel or conincident edges
-        a1 + a * cross(s, b) / cross(a, b);
-
 function bijection_offset(pts, d) = 
     let(
         es = __edges_from(pts), 
         offset_es = _bijection__bijection_offset_edges(es, d),
         leng = len(offset_es),
-        last_p = _bijection__bijection__bijection_offset_edges_intersection(offset_es[leng - 1], offset_es[0])
+        last_p = __line_intersection(offset_es[leng - 1], offset_es[0])
     )
     concat(
         [
@@ -67,7 +55,7 @@ function bijection_offset(pts, d) =
             let(
                 this_edge = offset_es[i],
                 next_edge = offset_es[i + 1],
-                p = _bijection__bijection__bijection_offset_edges_intersection(this_edge, next_edge)
+                p = __line_intersection(this_edge, next_edge)
             )
             // p == p to avoid [nan, nan], because [nan, nan] != [nan, nan]
             if(p != [] && p == p) p