feat: orient quads

feat: orient quads

Author: lgrcia

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "twirl"
-version = "0.5.0"
+version = "0.5.1"
 description = "Astrometric plate solving in Python"
 authors = ["Lionel J. Garcia <lionel_garcia@live.fr>"]
 maintainers = [

twirl/quads.py

@@ -29,7 +29,7 @@ def good_quads(quads, circletol=0.01):
     return np.all(in_circle, axis=1)
 
 
-def quad_hash(quads):
+def quad_hash(quads, oriented=True):
     a, b, c, d = np.rollaxis(quads, 1)
 
     norm = np.linalg.norm(b - a, axis=1)
@@ -48,6 +48,11 @@ def u1u2(a, b):
 
     u1, u2 = u1u2(a, b)
 
+    if oriented:
+        reverse = (np.cross((b - a), (b - c))) >= 0
+        # invert u1 and u2 for reversed quads
+        u1[reverse], u2[reverse] = u2[reverse], u1[reverse]
+
     def proj(p, origin, axe):
         """projection of a point p on a segment from origin to axe"""
         n = axe - origin