From db6819ccc659e663d598d5d068f34fc7d0c0d941 Mon Sep 17 00:00:00 2001
From: Jan Petykiewicz <anewusername@gmail.com>
Date: Tue, 27 Oct 2020 18:19:32 -0700
Subject: [PATCH] fix z-interpolation

---
 gridlock/draw.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/gridlock/draw.py b/gridlock/draw.py
index 371f32f..1e4917a 100644
--- a/gridlock/draw.py
+++ b/gridlock/draw.py
@@ -149,10 +149,10 @@ def draw_polygons(self,
             grid_coord = numpy.digitize(point, edges) - 1
             w_coord = grid_coord - bdi_min[surface_normal]
 
-            if grid_coord < 0:
+            if w_coord < 0:
                 w_coord = 0
                 f = 0
-            elif grid_coord >= w_z.size:
+            elif w_coord >= w_z.size:
                 w_coord = w_z.size - 1
                 f = 1
             else: