add better gyroid tile caching

src/geo/gyroid.js

@@ -6,17 +6,36 @@
 
     if (self.base.gyroid) return;
 
-    const base = self.base,
-        PI2 = Math.PI * 2;
+    const base = self.base;
+    const PI2 = Math.PI * 2;
+    let cache = {};
+    let lastVal;
+    let lastRes = 0;
+    let lastSlice = 0;
 
     /**
      * @param off {number} z offset value from 0-1
      * @param res {number} resolution (pixels/slices per side)
      */
     function slice(off, res, val) {
+        // auto clear cach if it hasn't been hit in the last 20 seconds
+        // or the requested resolution or tip values have changed
+        let now = Date.now();
+        if (res !== lastRes || val !== lastVal || now - lastSlice > 20000) {
+            // console.log({clear_cache: now});
+            cache = {};
+        }
+        lastVal = val;
+        lastRes = res;
+        lastSlice = now;
         let rez = parseInt(res || 200);
         let inc = PI2 / rez;
         let z = PI2 * off;
+        let key = (z % PI2).round(3);
+        let hit = cache[key];
+        if (hit) {
+            return hit;
+        }
         let tip = val || 0;
         let edge = [];
         let vals = [];
@@ -146,7 +165,9 @@
             .map(poly => filter(poly, 0))
             .map(poly => filter(poly, inc));
 
-        return {edge, points, dir, polys: psimple};
+        let slice = {edge, points, dir, polys: psimple};
+        cache[key] = slice;
+        return slice;
     }
 
     // merge co-linear and distance threshold

src/mode/fdm/slice.js

@@ -1333,7 +1333,7 @@
         let size = process.sliceSupportSize;
         let s4 = size / 4;
         let s2 = size * 0.45;
-        let min = 0.01;//process.sliceSupportArea || 1;
+        let min = 0.01;
         let geo = new THREE.BufferGeometry();
         geo.setAttribute('position', new THREE.BufferAttribute(widget.vertices, 3));
         let mat = new THREE.MeshBasicMaterial();