shape: Fix bend-seg intersection

By making zero-length bends non-intersectable.

src/math.rs

@@ -194,10 +194,12 @@ pub fn intersect_circle_segment(circle: &Circle, segment: &Line) -> Vec<Point> {
 pub fn between_vectors(p: Point, from: Point, to: Point) -> bool {
     let cross = cross_product(from, to);
 
-    if cross >= 0. {
-        cross_product(from, p) >= 0. && cross_product(p, to) >= 0.
+    if cross > 0.0 {
+        cross_product(from, p) >= 0.0 && cross_product(p, to) >= 0.0
+    } else if cross < 0.0 {
+        cross_product(from, p) >= 0.0 || cross_product(p, to) >= 0.0
     } else {
-        cross_product(from, p) >= 0. || cross_product(p, to) >= 0.
+        false
     }
 }
 

src/shape.rs

@@ -136,7 +136,7 @@ impl Shape {
                 Shape::Dot(..) => unreachable!(),
                 Shape::Seg(other) => seg.polygon().intersects(&other.polygon()),
                 Shape::Bend(other) => {
-                    /*for segment in seg.polygon().exterior().lines() {
+                    for segment in seg.polygon().exterior().lines() {
                         let inner_circle = other.inner_circle();
                         let outer_circle = other.outer_circle();
 
@@ -151,7 +151,7 @@ impl Shape {
                                 return true;
                             }
                         }
-                    }*/
+                    }
 
                     false
                 }