initial commit

src/battle/TypeChart.lua

@@ -0,0 +1,55 @@
+-- Gen 1 type effectiveness from generated data (multipliers x10).
+-- Like the original, each matchup row applies independently, so dual types
+-- multiply (e.g. 20 * 5 -> neutral).
+
+local TypeChart = {}
+
+local index -- [atk][def] -> x10 multiplier
+local matchups -- ROM-ordered TypeEffects rows
+
+function TypeChart.load(data)
+  index = {}
+  matchups = data.type_chart.matchups
+  for _, m in ipairs(matchups) do
+    index[m.attacker] = index[m.attacker] or {}
+    index[m.attacker][m.defender] = m.multiplier
+  end
+end
+
+-- The x10 multipliers of every TypeEffects row that applies, in ROM
+-- order.  AdjustDamageForMoveType applies each row to the running
+-- damage separately (one application per row even when both defender
+-- types match it), so callers must floor after every row.
+function TypeChart.rows(moveType, defenderTypes)
+  assert(matchups, "TypeChart.load not called")
+  local out = {}
+  for _, m in ipairs(matchups) do
+    if m.attacker == moveType then
+      for _, dt in ipairs(defenderTypes) do
+        if m.defender == dt then
+          out[#out + 1] = m.multiplier
+          break
+        end
+      end
+    end
+  end
+  return out
+end
+
+-- Returns the combined x10 multiplier of moveType against a types list
+-- (x100 for dual matchups is normalized back: each application is /10).
+function TypeChart.effectiveness(moveType, defenderTypes)
+  assert(index, "TypeChart.load not called")
+  local mult = 10
+  local row = index[moveType]
+  if not row then return mult end
+  for _, dt in ipairs(defenderTypes) do
+    local m = row[dt]
+    if m ~= nil then
+      mult = math.floor(mult * m / 10)
+    end
+  end
+  return mult
+end
+
+return TypeChart