Tilemap and Sprite Flags

These functions let your Lua code read the map you painted in the Map Editor and inspect the flags you set in the Sprite Editor.

mget

mget(x, y)

Read a tile from the map.

Parameters:

• x (number) – Tile column in the map grid.

• y (number) – Tile row in the map grid.

Returns:

Sprite index stored at that map cell.

mget uses tile coordinates, not pixel coordinates. Since each tile is 8 x 8 pixels, divide world positions by 8 and floor the result when converting a pixel position to a map tile.

Warning

Reading outside the map – the default map is 128 x 32 tiles, so columns 0–127 and rows 0–31 – raises a fatal runtime error that stops the game. Bounds-check the coordinates first (see the example below).

tile_x = math.floor(player.x / 8)
tile_y = math.floor((player.y + 8) / 8)
tile_sprite = mget(tile_x, tile_y)

fget

fget(spriteIndex, bit)

Read the flags stored on a sprite in the Sprite Editor.

Parameters:

• spriteIndex (number) – Sprite index in the sprite sheet (0–255).

• bit (number) – Optional bit index from 0 to 7.

Returns:

The full flag value when bit is omitted, or true/false for a single bit.

A spriteIndex outside 0–255 or a bit outside 0–7 raises a fatal runtime error that stops the game.

Use sprite flags to attach lightweight gameplay metadata to sprites. A common pattern is to mark map tile sprites with flag bits such as “solid” or “hazard”, then check those flags after reading tiles with mget().

tile_sprite = mget(tile_x, tile_y)

if fget(tile_sprite, 0) then
  -- bit 0 is enabled: treat this tile as solid
end

flags = fget(tile_sprite)  -- full 0-255 flag value

Tile collision example

TILE_SIZE = 8
MAP_W, MAP_H = 128, 32
FLAG_SOLID = 0

function is_solid_at_pixel(x, y)
  local tile_x = math.floor(x / TILE_SIZE)
  local tile_y = math.floor(y / TILE_SIZE)

  -- Outside the map: mget would raise an error, so treat it as empty
  if tile_x < 0 or tile_x >= MAP_W or tile_y < 0 or tile_y >= MAP_H then
    return false
  end

  return fget(mget(tile_x, tile_y), FLAG_SOLID)
end