From 4cc43e1661f37cdfdd6c059228e13701763f89ee Mon Sep 17 00:00:00 2001
From: Werner Almesberger <werner@almesberger.net>
Date: Tue, 20 Jan 2015 03:19:22 -0300
Subject: [PATCH] sfc/slicer.py: when flipping, also flip Z positions used for
 selecting levels

This led to toolpaths full of strange yet almost imperceptible errors
along the Z axis, just on the edge of what could be explained by
machining tolerances.
---
 sfc/slicer.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sfc/slicer.py b/sfc/slicer.py
index 8a48223..4c2210c 100755
--- a/sfc/slicer.py
+++ b/sfc/slicer.py
@@ -150,7 +150,10 @@ max_nz = 0
 inclined = 0
 for facet in mesh.Facets:
 	if abs(facet.Normal.z) >= 1 - epsilon:
-		z_raw[facet.Points[0][2]] = 1
+		z = facet.Points[0][2]
+		if flip:
+			z = bb.ZMax - z + bb.ZMin
+		z_raw[z] = 1
 	else:
 		nz = abs(facet.Normal.z)
 		if nz > epsilon: