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SMT Nine Font System

Technical reference for the game's font texture files, tile layout, and the XPR0 texture format.

Font Files

File Format Dimensions Tile Pitch Pages Layout Purpose
sys_f24.xpr DXT1 512×512 24px 9 Linear Main dialogue font (24pt)
sys_f18.xpr DXT1 512×512 18px 9 Linear Smaller UI text (18pt)
font.xpr A4R4G4B4 128×256 Variable 1 Morton-swizzled Battle font (italic, proportional)
font2.xpr A4R4G4B4 128×256 Variable 1 Morton-swizzled Battle font (bold, proportional)
systext.xpr DXT5 512×128 — — — System text labels (baked graphics)
orgtext.xpr DXT5 512×512 — — — Original text graphics
memtext.xpr DXT5 512×512 — — — Menu text graphics

Tile Grid Layout

sys_f24.xpr (24pt dialogue font)

  • Grid: 21 tiles/row × 21 tiles/col = 441 tiles per page
  • Total tiles: 441 × 9 pages = 3,969 (matches sysfont.tbl section 2)
  • Tile size: 24×24 pixels
  • Latin characters: Page 7, entries 3102–3163
Page 7 layout (partial):
Row 0: [kanji...] [0] [1] [2] [3] [4] [5]
Row 1: [6] [7] [8] [9] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q]
Row 2: [R] [S] [T] [U] [V] [W] [X] [Y] [Z] [a] [b] [c] [d] [e] [f] [g] [h] [i] [j] [k] [l]
Row 3: [m] [n] [o] [p] [q] [r] [s] [t] [u] [v] [w] [x] [y] [z] ...

sys_f18.xpr (18pt UI font)

  • Grid: 28 tiles/row × 28 tiles/col = 784 tiles per page
  • Total tiles: 784 × 9 pages = 7,056 (matches sysfont.tbl section 1)
  • Tile size: 18×18 pixels
  • Latin characters: Page 8, tiles 6908–6969

XPR0 Texture Format

File Structure

Offset 0:    "XPR0"         (4 bytes, magic)
Offset 4:    uint32 LE      total file size
Offset 8:    uint32 LE      header size / data offset
Offset 12:   resource_header[N]   (each 20 bytes)
...padding to header_size...
[texture data starts at header_size]

Resource Header (20 bytes each)

The D3D format word encodes the pixel format and dimensions:

Bits Field
8–15 Pixel format code
20–23 log2(width)
24–27 log2(height)

Pixel format codes:

Code Format Bits/Pixel Notes
0x0C DXT1 4 (compressed) Used by sys_f24, sys_f18
0x0F DXT5 8 (compressed) Used by systext, orgtext, memtext
0x04 A4R4G4B4 16 Used by font.xpr, font2.xpr

Page Data Layout

For DXT1 512×512 textures:

  • Block size: 4×4 pixels = 8 bytes per block
  • Blocks per page: 128 × 128 = 16,384
  • Bytes per page: 16,384 × 8 = 131,072 bytes
  • Data offset: header_size + (page_number × 131,072)

SysFont files use linear (row-major) block ordering. The battle fonts (font.xpr, font2.xpr) use Morton/Z-order swizzling. Always check which layout a file uses before decoding — applying the wrong unswizzle produces garbled output.

DXT1 Block Format

Each 8-byte DXT1 block encodes a 4×4 pixel region:

Bytes 0-1:   uint16 LE    color0 (RGB565)
Bytes 2-3:   uint16 LE    color1 (RGB565)
Bytes 4-7:   uint32 LE    2-bit index per pixel (16 pixels × 2 bits)

Color mode selection:

  • If color0 > color1: 4-color opaque mode
    • Index 0 = color0, Index 1 = color1
    • Index 2 = (2×color0 + color1) / 3
    • Index 3 = (color0 + 2×color1) / 3
  • If color0 <= color1: 3-color + 1-bit alpha mode
    • Index 0 = color0, Index 1 = color1
    • Index 2 = (color0 + color1) / 2
    • Index 3 = transparent black (0, 0, 0, 0)

The font glyphs use the 1-bit alpha mode for tiles that contain both glyph pixels and transparent background.

RGB565 Packing

uint16 = (R >> 3) << 11 | (G >> 2) << 5 | (B >> 3)

Where R, G, B are 8-bit values. Red and blue get 5 bits, green gets 6 bits.

Halfwidth Glyph Design

The original Latin glyphs are fullwidth — designed to fill the entire 24px or 18px tile width. For halfwidth rendering, replacement glyphs should:

  • Occupy approximately half the tile width (~11px for 24pt, ~8px for 18pt)
  • Be left-aligned within the tile (the renderer advances the cursor by half a tile width after a halfwidth character)
  • Use a transparent background for proper compositing
  • Match the original glyph brightness — the existing font uses approximately RGB(197, 198, 222)

The font_patch.py tool handles all of this automatically using DejaVu Sans Mono Bold as the source font.