add support point compensation for belt anchors

src/kiri/mode/fdm/work/belt.js

@@ -48,7 +48,8 @@ const BELT = {
  * @returns {void} Modifies slices array in place
  */
 export function generateBeltAnchor({ slices, widget, process, lineWidth, sliceHeight, sliceHeightBase, extruder }) {
-    let { cosf, slope } = widget.belt;
+    let { belt } = widget;
+    let { cosf, slope } = belt;
 
     // find adjusted zero point from slices
     let smin = Infinity;
@@ -100,6 +101,12 @@ export function generateBeltAnchor({ slices, widget, process, lineWidth, sliceHe
     let step = sliceHeight;
     let anchorlen = (process.beltAnchor || process.firstLayerBeltLead) * cosf;
 
+    // offset used in support generation
+    belt.anchor = {
+        added: adds,
+        len: anchorlen
+    };
+
     while (anchorlen && start && anchorlen >= sliceHeight) {
         let addto = start.down;
         if (!addto) {

src/kiri/mode/fdm/work/slice.js

@@ -481,7 +481,7 @@ export function sliceOne(settings, widget, onupdate, ondone) {
         let { belt } = widget;
         // apply belt transformations, if needed
         if (belt && paint) {
-            let { dy, angle } = belt;
+            let { anchor, angle, dy, slope } = belt;
             // make a copy we can modify
             paint = structuredClone(paint);
             for (let rec of paint) {
@@ -490,6 +490,10 @@ export function sliceOne(settings, widget, onupdate, ondone) {
                 let np = newPoint(point.y + dy, point.z, 0).rotate(angle * (Math.PI/180));
                 point.y = np.x;
                 point.z = np.y;
+                if (anchor) {
+                    point.y += anchor.len;
+                    point.z += anchor.len;
+                }
             }
         }
         // convert paint points to circles on matching slices
@@ -837,10 +841,6 @@ export function sliceOne(settings, widget, onupdate, ondone) {
             slice.widget = widget;
         }
 
-        // support generation using either
-        // enclosed shadow or manual painted supports
-        await processSupports();
-
         // process solid layers (top/bottom)
         await processSolidLayers();
 
@@ -875,6 +875,10 @@ export function sliceOne(settings, widget, onupdate, ondone) {
             });
         }
 
+        // support generation using either
+        // enclosed shadow or manual painted supports
+        await processSupports();
+
         // calculations only relevant when solid layers are used
         // layer boolean diffs need to be computed to find flat areas to fill
         // and overhangs that need to be supported. these are stored in flats