From dd181e96e2ba37df9a231b13904e04bc7df0c60b Mon Sep 17 00:00:00 2001
From: Stewart Allen <stewart.allen@gmail.com>
Date: Tue, 2 Mar 2021 19:43:04 -0500
Subject: [PATCH] add fractional shells. requires 'experimental' to be enabled
 for now. fixes #121

---
 src/kiri/init.js      |  2 +-
 src/mode/fdm/slice.js | 12 +++++++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/kiri/init.js b/src/kiri/init.js
index 1e5b1963..d070748b 100644
--- a/src/kiri/init.js
+++ b/src/kiri/init.js
@@ -1620,7 +1620,7 @@
             sliceHeight:         UC.newInput(LANG.sl_lahi_s, {title:LANG.sl_lahi_l, convert:UC.toFloat, modes:FDM}),
             sliceMinHeight:      UC.newInput(LANG.ad_minl_s, {title:LANG.ad_minl_l, bound:UC.bound(0,3.0), convert:UC.toFloat, modes:FDM, show: () => UI.sliceAdaptive.checked}),
             fdmSep:              UC.newBlank({class:"pop-sep", modes:FDM}),
-            sliceShells:         UC.newInput(LANG.sl_shel_s, {title:LANG.sl_shel_l, convert:UC.toInt, modes:FDM}),
+            sliceShells:         UC.newInput(LANG.sl_shel_s, {title:LANG.sl_shel_l, convert:UC.toFloat, modes:FDM}),
             sliceTopLayers:      UC.newInput(LANG.sl_ltop_s, {title:LANG.sl_ltop_l, convert:UC.toInt, modes:FDM}),
             sliceSolidLayers:    UC.newInput(LANG.sl_lsld_s, {title:LANG.sl_lsld_l, convert:UC.toInt, modes:FDM}),
             sliceBottomLayers:   UC.newInput(LANG.sl_lbot_s, {title:LANG.sl_lbot_l, convert:UC.toInt, modes:FDM}),
diff --git a/src/mode/fdm/slice.js b/src/mode/fdm/slice.js
index b0a68eee..b41e59e2 100644
--- a/src/mode/fdm/slice.js
+++ b/src/mode/fdm/slice.js
@@ -278,6 +278,16 @@
             // create shells and diff inner fillable areas
             forSlices(0.0, 0.2, slice => {
                 let params = getRangeParameters(settings, slice.index);
+                let shellFrac = (params.sliceShells - (params.sliceShells | 0));
+                let sliceShells = params.sliceShells | 0;
+                if (ctrl.danger && shellFrac) {
+                    let v1 = shellFrac > 0.5 ? 1 - shellFrac : shellFrac;
+                    let v2 = 1 - v1;
+                    let parts = Math.round(v2/v1) + 1;
+                    let rem = slice.index % parts;
+                    let trg = shellFrac > 0.5 ? 1 : parts - 1;
+                    sliceShells += rem >= trg ? 1 : 0;
+                }
                 let first = slice.index === 0;
                 let isBottom = slice.index < spro.sliceBottomLayers;
                 let isTop = slice.index > slices.length - spro.sliceTopLayers-1;
@@ -286,7 +296,7 @@
                 let spaceMult = first ? spro.firstLayerLineMult || 1 : 1;
                 let offset = shellOffset * spaceMult;
                 let fillOff = fillOffset * spaceMult;
-                let count = isSynth ? 1 : params.sliceShells;
+                let count = isSynth ? 1 : sliceShells;
                 doShells(slice, count, offset, fillOff, {
                     vase: vaseMode,
                     thin: spro.detectThinWalls && !isSynth,