From 3aa0df2ee45e5d002f25f6f01e84869c7c51058b Mon Sep 17 00:00:00 2001
From: Stewart Allen <stewart.allen@gmail.com>
Date: Sat, 1 May 2021 12:48:05 -0400
Subject: [PATCH] fix brims and move belt offset to export

---
 src/mode/fdm/export.js  |  3 ++-
 src/mode/fdm/prepare.js | 11 +++++++++--
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/mode/fdm/export.js b/src/mode/fdm/export.js
index 9903a13d..7b347b37 100644
--- a/src/mode/fdm/export.js
+++ b/src/mode/fdm/export.js
@@ -53,6 +53,7 @@
             blast = 0,
             blastz = 0,
             process = settings.process,
+            belt_add_y = process.firstLayerYOffset || 0,
             loops = process.outputLoops || 0,
             zhop = process.zHopDistance || 0, // range
             seekMMM = process.outputSeekrate * 60,
@@ -291,7 +292,7 @@
                 let zheight = path ? path.height || 0 : 0;
                 epos.x = originCenter ? -pos.x : device.bedWidth - pos.x;
                 epos.z = blastz = pos.z * icos;
-                epos.y = -pos.y + epos.z * bcos;
+                epos.y = -pos.y + epos.z * bcos + belt_add_y;
                 lout = epos;
             }
             if (emit.x) o.append(" X").append(epos.x.toFixed(decimals));
diff --git a/src/mode/fdm/prepare.js b/src/mode/fdm/prepare.js
index 905ecf29..cf67abb0 100644
--- a/src/mode/fdm/prepare.js
+++ b/src/mode/fdm/prepare.js
@@ -459,9 +459,16 @@
         // post-process for base extrusions (touching the bed)
         if (isBelt) {
             // // correct y offset to desired layer offset
-            let miny = process.firstLayerYOffset || 0;
-            let thresh = firstLayerHeight * 0.25;
             let seqn = 0;
+            // tune base threshold
+            let thresh = Infinity;
+            for (let layer of output) {
+                for (let rec of layer) {
+                    let point = rec.point;
+                    thresh = Math.min(thresh, point.z - point.y);
+                }
+            }
+            thresh = thresh + firstLayerHeight * 0.25;
             // iterate over layers, find extrusion on belt and
             // apply corrections and add brim when specified
             for (let layer of output) {