feat(mods): expose map overviews in Gold

src/world/MapOverview.lua

@@ -0,0 +1,84 @@
+-- Generation-neutral minimap rasterization. WorldAPI arms own semantic
+-- markers because object/event visibility differs; terrain and tile shading
+-- share one output contract.
+
+local Assets = require("src.render.Assets")
+
+local MapOverview = {}
+local overviewShades = {}
+
+Assets.register(function() overviewShades = {} end)
+
+local function shadeDigit(sum, pixelCount)
+  return tostring(math.max(0, math.min(3,
+    math.floor((1 - sum / pixelCount) * 3 + 0.5))))
+end
+
+local function tileRows(map)
+  local tileset = map.tileset
+  if not (tileset and tileset.image and tileset.tilesPerRow) then return nil end
+  local cached = overviewShades[tileset.image]
+  if not cached then
+    local ok, pixels = pcall(Assets.imageData, tileset.image)
+    if not ok then return nil end
+    cached = { pixels = pixels, shades = {} }
+    overviewShades[tileset.image] = cached
+  end
+  local rows, detailRows, perRow = {}, {}, tileset.tilesPerRow
+  for ty = 0, map.heightCells * 2 - 1 do
+    local row, detailTop, detailBottom = {}, {}, {}
+    for tx = 0, map.widthCells * 2 - 1 do
+      local tile = map:tileAt(tx, ty)
+      local shades = cached.shades[tile]
+      if shades == nil then
+        local sums = { 0, 0, 0, 0 }
+        local ox, oy = (tile % perRow) * 8, math.floor(tile / perRow) * 8
+        for py = 0, 7 do
+          for px = 0, 7 do
+            local r, g, b = cached.pixels:getPixel(ox + px, oy + py)
+            local quadrant = math.floor(py / 4) * 2 + math.floor(px / 4) + 1
+            sums[quadrant] = sums[quadrant]
+              + r * 0.2126 + g * 0.7152 + b * 0.0722
+          end
+        end
+        shades = {
+          shadeDigit(sums[1] + sums[2] + sums[3] + sums[4], 64),
+          shadeDigit(sums[1], 16), shadeDigit(sums[2], 16),
+          shadeDigit(sums[3], 16), shadeDigit(sums[4], 16),
+        }
+        cached.shades[tile] = shades
+      end
+      row[#row + 1] = shades[1]
+      detailTop[#detailTop + 1] = shades[2] .. shades[3]
+      detailBottom[#detailBottom + 1] = shades[4] .. shades[5]
+    end
+    rows[#rows + 1] = table.concat(row)
+    detailRows[#detailRows + 1] = table.concat(detailTop)
+    detailRows[#detailRows + 1] = table.concat(detailBottom)
+  end
+  return rows, detailRows
+end
+
+function MapOverview.build(map, markers)
+  local rows = {}
+  for y = 0, map.heightCells - 1 do
+    local row = {}
+    for x = 0, map.widthCells - 1 do
+      row[#row + 1] = map:isWarpTileCell(x, y) and "+"
+        or map:isWaterCell(x, y) and "~"
+        or map:isWalkableCell(x, y) and "." or " "
+    end
+    rows[#rows + 1] = table.concat(row)
+  end
+  local tiles, detail = tileRows(map)
+  return { mapId = map.id, width = map.widthCells,
+           height = map.heightCells, rows = rows, markers = markers,
+           tileRows = tiles,
+           tileWidth = tiles and map.widthCells * 2,
+           tileHeight = tiles and map.heightCells * 2,
+           tileDetailRows = detail,
+           tileDetailWidth = detail and map.widthCells * 4,
+           tileDetailHeight = detail and map.heightCells * 4 }
+end
+
+return MapOverview