feat: New theme + wire price adjustement

public/js/engine/formulas.js

@@ -25,6 +25,30 @@ export function maxAffordable(base, growth, owned, budget) {
   return Math.max(n, 0);
 }
 
+/**
+ * Raw-material price per unit of material, before market noise. Expensive at
+ * first, then cheaper relative to revenue as the operation scales
+ * (economies of scale): it falls from `startUnitPrice` towards `floorUnitPrice`.
+ */
+export function materialUnitPrice(mm, totalProduced) {
+  const scale = 1 / Math.sqrt(1 + totalProduced / mm.scale);
+  return mm.floorUnitPrice + (mm.startUnitPrice - mm.floorUnitPrice) * scale;
+}
+
+/**
+ * What one purchase of material looks like. The lot grows with the operation
+ * (a share of everything produced so far, or `batchSecondsOfProduction` of
+ * current output), in doubling steps so the price stays readable.
+ * `factor` is the market's current noise, `discount` comes from upgrades.
+ */
+export function materialBatch(mm, totalProduced, rate, factor, discount) {
+  const basis = Math.max(totalProduced * mm.batchShareOfTotal, rate * mm.batchSecondsOfProduction);
+  const doublings = Math.max(0, Math.floor(Math.log2(Math.max(1, basis / mm.minBatch))));
+  const size = mm.minBatch * 2 ** doublings;
+  const cost = Math.max(1, Math.ceil(size * materialUnitPrice(mm, totalProduced) * factor * discount));
+  return { size, cost };
+}
+
 /**
  * Units customers want to buy per second at `price`.
  * Demand is maxed at or below the fair price and drops steeply above it, so