--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/pkg/mesh/util.go	Tue Nov 05 14:30:22 2019 +0100
@@ -0,0 +1,37 @@
+// Copyright (C) 2018 Michael Fogleman
+//
+// Permission is hereby granted, free of charge, to any person obtaining
+// a copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,
+// and/or sell copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+package mesh
+
+import "math"
+
+var (
+	eps      = math.Nextafter(1, 2) - 1
+	infinity = math.Inf(1)
+)
+
+func pseudoAngle(dx, dy float64) float64 {
+	p := dx / (math.Abs(dx) + math.Abs(dy))
+	if dy > 0 {
+		p = (3 - p) / 4
+	} else {
+		p = (1 + p) / 4
+	}
+	return math.Max(0, math.Min(1-eps, p))
+}