mock up basic thinwall w/out medial axis

src/kiri/core/print.js

@@ -138,16 +138,17 @@ class Print {
         }
 
         poly.forEachPoint((point, pos, points, count) => {
-            if (first) {
+            if (first || point.skip) {
-                if (options.onfirst) {
+                // if (point.skip) console.log({ skip: point });
+                if (first && options.onfirst) {
                     options.onfirst(point);
                 }
                 // move to first output point on poly
                 let out = scope.addOutput(output, point, 0, moveSpeed, tool);
-                if (options.onfirstout) {
+                if (first && options.onfirstout) {
                     options.onfirstout(out);
                 }
-                first = false;
+                if (first) first = false;
             } else {
                 let seglen = last.distTo2D(point);
                 if (coastDist && shellMult && perimeter - seglen <= coastDist) {
@@ -158,6 +159,7 @@ class Print {
                     shellMult = 0;
                 }
                 perimeter -= seglen;
+                // to increase shellMult when point.inc set for collapsed points
                 scope.addOutput(output, point, shellMult, printSpeed, tool);
             }
             last = point;

src/kiri/mode/fdm/post.js

@@ -99,6 +99,37 @@ function offset_default(params) {
             }
         }
     );
+    // look for close points on segmented polys
+    if (false)
+    for (let poly of POLY.flatten(last)) {
+        let ps = poly.segment(offset1, true);
+        let pp = ps.points;
+        let moved = false;
+        pp.push(pp[0]);
+        for (let i=0; i<pp.length; i++) {
+            let p0 = pp[i];
+            if (p0.moved) continue;
+            for (let j=i+1; j<pp.length; j++) {
+                let p1 = pp[j];
+                if (p1.moved) continue;
+                if (p0.segment === p1.segment) {
+                    continue;
+                }
+                if (p0.distTo2D(p1) < offset1) {
+                    // merge points marking point offset and skip
+                    let mid = p0.midPointTo(p1);
+                    let inc = p0.distTo2D(mid);
+                    moved = p0.moved = p1.moved = inc;
+                    p1.skip = true;
+                    p0.x = p1.x = mid.x;
+                    p0.y = p1.y = mid.y;
+                }
+            }
+        }
+        if (moved) {
+            poly.points = pp;
+        }
+    }
     return { last, gaps };
 }