Colour map
From Worms Knowledge Base
Support for PNG colour maps were added to Worms Armageddon with the v3.6.19.7 Beta Update (released on 9 February 2004). W:A maps need to be in a paletted 256-colour mode. The number of colours that may appear in the map is restricted as well. W:A stores the extra map settings (water level, borders, etc.) in an extra PNG chunk.
The black colour, which must be present in the colour palette, is considered as transparent (zones/pixels painted black will appear as free space in the game).
Map size
Versions of W:A before 3.6.27.0 only allowed maps that are exactly 1920×696 pixels in size. Version 3.6.27.0 introduced support for arbitrarily-sized maps, with the following restrictions:
- the width of a map must be divisible by 64;
- the height of a map must be divisible by 232;
- the width of a map must be at least 1920 pixels and at most 32704 pixels;
- the height of a map must be at least 232 pixels and at most 32712 (?) pixels;
- TODO: get total area or map filesize restriction.
Colour limitation
Since W:A uses a paletted display, the number of colours that may appear simultaneously on-screen is limited. The majority of the colour space is used for in-game graphics for the Worms, weapons, objects, water, UI elements, etc. Therefore, the colour maps may only use a limited number of colours in the palette (not counting black, which is treated as transparent), without affecting other Worms graphics:
- 64 colours and less - the map will be displayed perfectly, with no glitches;
- 65-96 colours - the map background sprites (falling debris, clouds, etc.) are removed;
- 97-112 colours - the entire background becomes solid black;
- 113 colours and more - the map will not load.
PNG chunk
W:A stores the extra settings in an extra PNG chunk, labeled w2lv or waLV. The chunk, excluding the label header, is 40 bytes long, and seems to contain the same data as the header for monochrome maps.
TweakPNG allows manipulation of PNG images on the chunk level, thus allowing chunk import/export, etc.
