From fa71d252bf1d8f0aec26773849b0e61b9b818db1 Mon Sep 17 00:00:00 2001
From: Justin Lin <caterpillar@openhome.cc>
Date: Thu, 20 Feb 2020 08:39:45 +0800
Subject: [PATCH] support depth

---
 src/experimental/_impl/_sf_square_surfaces.scad | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/experimental/_impl/_sf_square_surfaces.scad b/src/experimental/_impl/_sf_square_surfaces.scad
index 11778f18..999a61e4 100644
--- a/src/experimental/_impl/_sf_square_surfaces.scad
+++ b/src/experimental/_impl/_sf_square_surfaces.scad
@@ -1,13 +1,14 @@
-function _sf_square_surfaces(levels, thickness, invert) =
+function _sf_square_surfaces(levels, thickness, depth, invert) =
     let(
         rows = len(levels),
         columns = len(levels[0]),
+        offset_z = invert ? 0 : thickness - depth,
         surface1 = [
             for(r = [0:rows - 1]) 
             [
                 for(c = [0:columns - 1]) 
-                let(lv = (invert ? 255 - levels[rows - r - 1][c] : levels[rows - r - 1][c]) + 1) // minimum level is 1
-                [c, r, lv / 255 * thickness]
+                let(lv = invert ? 255 - levels[rows - r - 1][c] : levels[rows - r - 1][c])
+                [c, r, lv / 255 * depth + offset_z]
             ]
         ],
         surface2 = [