replace logic in spline intersection which depends on 2D side-of function

modules/curve_utils.py

@@ -20,11 +20,6 @@
 
 import bpy
 
-def line_point_side_v2(l1, l2, pt):
-    return (((l1[0] - pt[0]) * (l2[1] - pt[1])) -
-            ((l2[0] - pt[0]) * (l1[1] - pt[1])))
-
-
 def vis_curve_object():
     scene = bpy.data.scenes[0] # weak!
     cu = bpy.data.curves.new(name="Line", type='CURVE')
@@ -370,24 +365,32 @@ def points_to_bezier(points_orig,
             # raise Exception("END")
 
         def intersect_line(self, l1, l2, reverse=False):
+            """ Spectial kind of intersection, works in 3d on the plane
+                defimed by the points normal and the line.
+            """
 
             from mathutils.geometry import (intersect_point_line,
                                             )
 
             if reverse:
-                p_first = self.points[-2]
+                p_first = self.points[-1]
+                no = -self.points[-1].no
                 point_iter = reversed(self.points[:-1])
             else:
-                p_first = self.points[1]
+                p_first = self.points[0]
+                no = self.points[0].no
                 point_iter = self.points[1:]
 
-            side = (line_point_side_v2(l1, l2, p_first.co) < 0.0)
-            ok = False
+            # calculate the line right angles to the line
+            bi_no = (no - no.project(l2 - l1)).normalized()
+
+            bi_l1 = p_first.co
+            bi_l2 = p_first.co + bi_no
+
             for p_apex in point_iter:
-                if (line_point_side_v2(l1,
-                                       l2,
-                                       p_apex.co,
-                                       ) < 0.0) != side:
+                ix, fac = intersect_point_line(p_apex.co, bi_l1, bi_l2)
+                
+                if fac < 0.0001:
 
                     if reverse:
                         p_apex_other = p_apex.next
@@ -407,12 +410,12 @@ def points_to_bezier(points_orig,
                     w2 = (p_test_2 - p_apex_other.co).length
                     
                     #assert(w1 + w2 != 0)
-                    #try:
-                    fac = w1 / (w1 + w2)
-                    #except ZeroDivisionError:
-                    #    fac = 0.5
+                    try:
+                        fac = w1 / (w1 + w2)
+                    except ZeroDivisionError:
+                        fac = 0.5
                     assert(fac >= 0.0 and fac <= 1.0)
-                    
+
                     p_apex_co = p_apex.co.lerp(p_apex_other.co, fac)
                     p_apex_no = p_apex.no.lerp(p_apex_other.no, fac)
                     p_apex_no.normalize()