From 6a1b141d5c62dd692620f12efb9791f11d88a3c9 Mon Sep 17 00:00:00 2001
From: Adrian Mariano <avm4@cornell.edu>
Date: Fri, 5 Mar 2021 20:39:15 -0500
Subject: [PATCH] hull 2d tweak
---
hull.scad | 18 +++++++++---------
tests/test_hull.scad | 8 ++++----
2 files changed, 13 insertions(+), 13 deletions(-)
diff --git a/hull.scad b/hull.scad
index fbfecdb..5658bec 100644
--- a/hull.scad
+++ b/hull.scad
@@ -80,7 +80,7 @@ function _backtracking(i,points,h,t,m) =
_backtracking(i,points,h,t,m-1) ;
// clockwise check (2d)
-function _is_cw(a,b,c) = cross(a-c,b-c)<=0;
+function _is_cw(a,b,c) = cross(a-c,b-c)<-EPSILON*norm(a-c)*norm(b-c);
// Function: hull2d_path()
@@ -100,13 +100,7 @@ function _is_cw(a,b,c) = cross(a-c,b-c)<=0;
//
function hull2d_path(points) =
assert(is_path(points,2),"Invalid input to hull2d_path")
- len(points) < 2 ? []
- : len(points) == 2 ? [0,1]
- : let(tri=noncollinear_triple(points, error=false))
- tri == [] ? _hull_collinear(points)
- :
- assert(is_path(points,2))
- assert(len(points)>=3, "Point list must contain at least 3 points.")
+ len(points) < 2 ? [] :
let( n = len(points),
ip = sortidx(points) )
// lower hull points
@@ -134,13 +128,19 @@ function hull2d_path(points) =
function _hull_collinear(points) =
let(
a = points[0],
- n = points[1] - a,
+ i = max_index([for(pt=points) norm(pt-a)]),
+ n = points[i] - a
+ )
+ norm(n)==0 ? [0]
+ :
+ let(
points1d = [ for(p = points) (p-a)*n ],
min_i = min_index(points1d),
max_i = max_index(points1d)
) [min_i, max_i];
+
// Function: hull3d_faces()
// Usage:
// hull3d_faces(points)
diff --git a/tests/test_hull.scad b/tests/test_hull.scad
index 3aba71a..a6a7926 100644
--- a/tests/test_hull.scad
+++ b/tests/test_hull.scad
@@ -6,9 +6,9 @@ module test_hull() {
assert_equal(hull([[3,4,1],[5,5,3]]), [0,1]);
test_collinear_2d = let(u = unit([5,3])) [ for(i = [9,2,3,4,5,7,12,15,13]) i * u ];
- assert_equal(hull(test_collinear_2d), [7,1]);
+ assert_equal(sort(hull(test_collinear_2d)), [1,7]);
test_collinear_3d = let(u = unit([5,3,2])) [ for(i = [9,2,3,4,5,7,12,15,13]) i * u ];
- assert_equal(hull(test_collinear_3d), [7,1]);
+ assert_equal(sort(hull(test_collinear_3d)), [1,7]);
/* // produces some extra points along edges
test_square_2d = [for(x=[1:5], y=[2:6]) [x,y]];
@@ -105,9 +105,9 @@ module test_hull2d_path() {
assert_equal(hull([[3,4,1],[5,5,3]]), [0,1]);
test_collinear_2d = let(u = unit([5,3])) [ for(i = [9,2,3,4,5,7,12,15,13]) i * u ];
- assert_equal(hull(test_collinear_2d), [7,1]);
+ assert_equal(sort(hull(test_collinear_2d)), [1,7]);
test_collinear_3d = let(u = unit([5,3,2])) [ for(i = [9,2,3,4,5,7,12,15,13]) i * u ];
- assert_equal(hull(test_collinear_3d), [7,1]);
+ assert_equal(sort(hull(test_collinear_3d)), [1,7]);
rand10_2d = [[1.55356, -1.98965], [4.23157, -0.947788], [-4.06193, -1.55463],
[1.23889, -3.73133], [-1.02637, -4.0155], [4.26806, -4.61909],