# HG changeset patch
# User Sascha L. Teichmann <sascha.teichmann@intevation.de>
# Date 1537347780 -7200
# Node ID 9a0246ab3021b09fb24b5a3f7a49d6e03dbe0528
# Parent  5fa2eaffac84be598ec7c551d3c2a3cd48de13f6
octree: simplified vertex interpolation.

diff -r 5fa2eaffac84 -r 9a0246ab3021 cmd/tin2octree/vertex.go
--- a/cmd/tin2octree/vertex.go	Wed Sep 19 10:57:37 2018 +0200
+++ b/cmd/tin2octree/vertex.go	Wed Sep 19 11:03:00 2018 +0200
@@ -30,12 +30,21 @@
 	}
 }
 
+func (v vertex) sub(w vertex) vertex {
+	return vertex{
+		v.x - w.x,
+		v.y - w.y,
+		v.z - w.z,
+	}
+}
+
 func interpolate(v1, v2 vertex) func(vertex) vertex {
+	v2 = v2.sub(v1)
 	return func(s vertex) vertex {
 		return vertex{
-			(v2.x-v1.x)*s.x + v1.x,
-			(v2.y-v1.y)*s.y + v1.y,
-			(v2.z-v1.z)*s.z + v1.z,
+			v2.x*s.x + v1.x,
+			v2.y*s.y + v1.y,
+			v2.z*s.z + v1.z,
 		}
 	}
 }