change ease down behavior. no longer use step down to lift Z

src/kiri-mode/cam/ops.js

@@ -466,7 +466,7 @@ class OpRough extends CamOp {
         sliceOutput(sliceOut, {
             cutdir,
             depthFirst,
-            easeDown: op.down && easeDown ? op.down : 0,
+            easeDown: op.down && easeDown ? 0.001 : 0,
             progress: (n,m) => progress(n/m, "routing")
         });
     }
@@ -725,7 +725,7 @@ class OpOutline extends CamOp {
                     .sort((a,b) => { return a.area() - b.area() })[0]
                     .average();
                 // experimental start of ease down
-                let ease = op.down && easeDown ? op.down : 0;
+                let ease = op.down && easeDown ? 0.001 : 0;
                 printPoint = depthOutlinePath(printPoint, 0, flatLevels, toolDiam, polyEmit, false, ease);
                 printPoint = depthOutlinePath(printPoint, 0, flatLevels, toolDiam, polyEmit, true, ease);
             }

src/kiri-mode/cam/prepare.js

@@ -568,6 +568,12 @@ function prepEach(widget, settings, print, firstPoint, update) {
         newLayer();
     }
 
+    // prepare
+    // sliceOutput
+    // depthRoughPath
+    // poly2polyEmit
+    // roughTopEmit
+    // poly2polyEmit
     function polyEmit(poly, index, count, fromPoint) {
         let last = null;
         // scale speed of first cutting poly since it engages the full bit

src/kiri-mode/fdm/prepare.js

@@ -1172,7 +1172,7 @@ function slicePrintPath(print, slice, startPoint, offset, output, opt = {}) {
             raft = opt.raft || false,
             flow = opt.flow || 1,
             near = opt.near || (antiBacklash ? false : true),
-            fast = opt.fast || false,
+            fast = opt.fast || false, // support infill only!
             fill = (opt.fill >= 0 ? opt.fill : fillMult) * flow,
             thinDist = near ? thinWall : thinWall;
 
@@ -1192,6 +1192,7 @@ function slicePrintPath(print, slice, startPoint, offset, output, opt = {}) {
                 t2 = lines[i+1];
                 let d1 = t1.distToSq2D(startPoint);
                 let d2 = t2.distToSq2D(startPoint);
+                // penalize next nearest point if it's not on an adjacent line
                 let idiff = startPoint.index ? Math.abs(startPoint.index - t1.index) : 1;
                 let min = Math.min(d1, d2) * (idiff !== 1 ? 10 : 1);
                 if (min < mindist) {