parallelize widget shadow generation 2x faster

src/kiri/mode/cam/op-index.js

@@ -8,10 +8,10 @@ export class OpIndex extends CamOp {
     }
 
     weight() {
-        return 0.1;
+        return 3;
     }
 
-    async slice() {
+    async slice(progress) {
         let { op, state } = this;
 
         if (!state.isIndexed) {
@@ -37,7 +37,7 @@ export class OpIndex extends CamOp {
         updateSlicer();
 
         // recompute shadow from new widget geometry
-        await computeShadows();
+        await computeShadows(progress);
     }
 
     prepare(ops, progress) {

src/kiri/mode/cam/op-shadow.js

@@ -22,7 +22,7 @@ class OpShadow extends CamOp {
     }
 
     weight() {
-        return 0.1;
+        return 3;
     }
 
     async slice(progress) {
@@ -50,6 +50,9 @@ class OpShadow extends CamOp {
             tzindex = [ ];
         }
 
+        // distributed pre-fill shadow layer cache
+        await widget.computeShadowStack(tzindex, prog => progress(prog / 2, 'shadow'));
+
         // terrain is the "shadow stack" where index 0 = top of part
         // thus array.length -1 = bottom of part
         for (let i=0; i<tzindex.length; i++) {
@@ -65,7 +68,7 @@ class OpShadow extends CamOp {
                     .setLayer("shadow", {line: 0x888800, thin: true })
                     .addPolys(shadow, { thin: true });
             }
-            progress(i / tzindex.length);
+            progress(0.5 + i / tzindex.length, 'shadow');
         }
 
         if (devel && slices.length) {

src/kiri/mode/cam/slice.js

@@ -261,12 +261,10 @@ export async function cam_slice(settings, widget, onupdate, ondone) {
         return slicer = state.slicer = new cam_slicer(widget, opts);
     }
 
-    async function computeShadows() {
-        console.time('computeShadows');
-        await new OPS.shadow(state, { type: "shadow", silent: true }).slice(progress => {
-            // console.log('reshadowing', progress.round(3));
-        });
-        console.timeEnd('computeShadows');
+    async function computeShadows(progress) {
+        console.time('compute shadow');
+        await new OPS.shadow(state, { type: "shadow", xsilent: true }).slice(progress);
+        console.timeEnd('compute shadow');
     }
 
     function setToolDiam(toolDiam) {