DO/Updated Sprite Format
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Overall Structure
The overall structure of a sprite file looks a like this (in this order):
SPRITE FILE HEADER <size=32> FRAME HEADER 1 <size=32> FRAME HEADER 2 <size=32> . . FRAME HEADER (number of frames) <size=32> PALETTE ENTRY 1 <size=4> PALETTE ENTRY 2 <size=4> . . PALETTE ENTRY (number of palette entries) <size=4> FRAME 1 DATA <size=varies> FRAME 2 DATA <size=varies> . . FRAME (number of frames) DATA <size=varies>
For a description of each part, see below.
Sprite File Header
The file header consists of the first 32 bytes of the file
struct SpriteFileHeader { char ID[4]; // = 'WHDO' int filesize; // = the size of the file in bytes int version?; // = 32 int frameDataOffset // = file offset to beginning of the frame data int paletteDataOffset // = file offset to beginning of the palette data int paletteEntryCount // = the total number of palette entries (*) int paletteCount // = how many unique palettes exist in this sprite int frameCount // = the number of frames of animation in this sprite }
(* This is the total number of colours stored in the file, each of which belongs only to one palette. e.g. there may be 300 colours stored in the file, spread throughout 5 different palettes; the paletteEntryCount is 300, the paletteCount is 5 )
Frame Headers
There is one frame header for each animation frame in the sprite:
struct FrameHeader { byte frameType; // see table below (1) byte compressionType; // 0: not compressed, 1: packbits, 2: unknown (2) short colourCount; // = the number of unique colours in the frame signed short X; // = X position of this frame signed short Y; // = Y position of this frame short frameWidth; // = width of this frame short frameHeight; // = height of this frame int dataOffset; // = offset into the frame data (3) int compressedSize; // = length of the compressed frame data int uncompressedSize; // = length of the uncompressed frame data int paletteDataOffset; // = offset into the palette data int unknown; // = 0 }
1. Frame Type
Each frame has a type:
Type Description 4 This is a normal frame. 5 The frame is empty. i.e. there is no frame or palette data associated with this frame. Width and Height are 0.
2. Frame Compression
Frames can be compressed. Unit sprite files seem to use no compression at all, animations for encounters between battles (filename beginning M_) can be compressed using two methods (or be uncompressed).
Compression Type Decription 0 Uncompressed - the frame data consists of 1 byte indices in to the associated palette 1 Packbits - the frame is compressed using the PACKBITS compression scheme. 2 Unknown - the frame is compressed using an unknown compression algorithm
3. Offset Into the Frame Data
This offset is into the frame data. i.e. this frame's data is at SpriteHeader.frameDataOffset + FrameHeader.dataOffset
Palette Data
Each colour is stored as follows:
struct PaletteEntry { byte blue; byte green; byte red; byte padding; // =0 not used }