DragonHD
154 lines
6.6 KiB
Markdown
154 lines
6.6 KiB
Markdown
# Font rendering map + double-byte patch
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## Font object layout (size `0x191C`, embedded by value in a manager struct)
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Two UI font objects live at `manager + 0x3A8` and `manager + 0x1CC4` (difference = `0x191C`).
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```
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+0x00 texture pointer (D3D texture object)
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+0x04 max width
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+0x08 max height
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+0x0C SpaceWidth
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+0x10 LineDistance
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+0x14 CharDistance
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+0x18 flag (1 = built)
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+0x1C 256 glyph entries x 16 bytes = 4 floats (u1,v1,u2,v2) normalized UV
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+0x101C 256 metric entries x 8 bytes = { int advance, int height }
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+0x181C 256 "defined" bytes
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```
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The table stride differs (16 vs 8 vs 1), which is why the tables cannot be enlarged in place and a
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side table is used for CJK.
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## Key code
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| VA | role |
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|---|---|
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| `0x4EBF90` | parse/load `Fonts.dat` (generic config reader) |
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| `0x4E7DC0` | set font texture |
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| `0x4E7E30` | `AddChar(code, x1,y1,x2,y2)` — normalizes rect → stores glyph float[4] + metric[2] |
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| `0x4EC168` | `mov cl,[ebp]` — parser takes only the **first byte** of `Code` |
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| `0x4E7FD0` | measure text; loop body `0x4E7FF0`; metric lookups `0x4E802C`, `0x4E8033` |
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| `0x4EAC40` | draw text; loop head |
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| `0x4EACB0` | `movzx ecx,al` — glyph lookup site in draw loop |
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| `0x4EACDC`,`0x4EAE9A` | metric lookups in draw loop |
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| `0x4E56A0` | `IsCharDefined(font, code)` |
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Texture is bound **once per draw call** (`[font]` + vtable `+0xF4`), so ASCII and CJK glyphs must
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share one texture atlas.
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## Patch design (implemented)
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A new PE section `.cjk` holds two code caves and two big tables:
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```
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.cjk RVA 0x566000 (VA 0x966000), size 0x1C0000
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0x00 draw_cave
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0x0100 metrics_cave
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0x0200 cjk_glyph : 65536 x 16 bytes (u1,v1,u2,v2 floats)
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0x100200 cjk_metric : 65536 x 8 bytes (advance,height ints)
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```
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Hooks (5-byte `jmp rel32`):
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- `0x4EACB0 -> draw_cave` (was `movzx ecx,al`)
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- `0x4E8026 -> metrics_cave` (was `mov ebp,[ecx+0x14]`)
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Behaviour of each cave:
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- `al < 0x80`: execute the original instructions, jump back to the next instruction.
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- `al >= 0x80`: decode a 2-byte code `(al<<8)|[ptr+1]`; copy the glyph float[4] into font glyph slot
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`0xFF` and the metric into slot `0xFF`; set `ecx = 0xFF`, advance the string pointer by one extra
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byte; jump back into the engine's unchanged quad-building code.
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Slot `0xFF` glyph lives at `font+0x100C`, its metric at `font+0x1814`; these do not collide with the
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real tables.
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## Byte-order detail (important)
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Both caves must build the code identically as `(first << 8) | second`:
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- draw cave: `movzx ecx,al; shl ecx,8; movzx eax,[edx+1]; or ecx,eax`
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- metrics cave: `movzx eax,al; shl eax,8; mov al,[ebx+1]` (`al` is free after the `shl`)
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The metrics cave originally used `mov ah,[ebx+1]` which yields `(second<<8)|first`; CJK then
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measured as width 0 and centred labels were flushed right. Fixed.
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## Font atlas (implemented, `tools/build_cjk.py`)
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`AddChar` normalises rects by the **actual D3D texture size**, so replacing the UI font texture
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with a larger atlas that still contains the original ASCII art at pixel (0,0) keeps every existing
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`Fonts.dat` rect valid — no `Fonts.dat` edits needed.
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```
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Shrift_gb_Germany.TGA 2048 x 1024, 32bpp TGA (type 2, bottom-up, desc 0x08, 26-byte footer)
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(0,0) 256x128 original ASCII/German artwork (byte-identical copy)
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(0,128)+ 12x12 cells, 170 per row, full GB2312 (7445 codes), simsun 12px, binary alpha
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```
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`cjk_glyph` holds normalised UVs `(x/2048, y/1024, (x+12)/2048, (y+12)/1024)`;
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`cjk_metric` holds `(12, 12)` (advance, height). Deployed as a loose file and inside
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`Textures.res` (see `tools/install_cjk.py`).
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## Requirements / limits
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- The font texture must contain **both** ASCII and CJK glyphs (one texture per draw); done via the
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shared atlas above.
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- Lead bytes >= `0x80` are reserved for DBCS. ASCII is untouched.
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- Only the `UI` font atlas is extended; the `OldUI` / `UISmall` / Russian fonts still point at their
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own textures, so CJK drawn with those would need their own atlas/tables too.
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## Tools
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### Option-title centering
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Four original title sites push reference x=620 and directly draw text. The
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panel/Bind button center is reference x=640 (`0x4D8646`). Patch the title
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anchors to x=640 and redirect their draw calls to `.cjk+0x180500`:
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| Page | Anchor instruction | Draw call |
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|---|---|---|
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| Audio | `0x4D748C` | `0x4D74A6` |
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| Game | `0x4D9A1C` | `0x4D9A36` |
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| Video | `0x4DDAB4` | `0x4DDACE` |
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| Controls | `0x4DE8C8` | `0x4DE8E2` |
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The wrapper preserves registers, measures the supplied font/text using
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`0x4E7FD0`, subtracts half the measured width from the already transformed
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screen point, and tail-jumps to `0x4EAB70`. Ordinary option rows and unrelated
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draw calls retain their existing placement. Input opcodes are checked before
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these title edits. `tools/test_cjk_titles.py` tests the actual call-site code,
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coordinate transformation, measurement, and resulting draw positions.
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### Wrapped-text layout correction
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`0x4ED380` wraps/aligns tooltip paragraphs separately from the plain draw and
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measure loops. Its one-byte temporary string must be extended to a full GB2312
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character, otherwise a Chinese-only line has zero measured glyph height.
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New hooks (all addresses apply to the documented Steam executable):
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| Hook | Cave offset in .cjk | Purpose |
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| `0x4ED430` | `0x180200` | Prepare a NUL-terminated one/two-byte character; preserve control-code flags |
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| `0x4ED50E` | `0x180300` | Append complete character, advance byte index, retain width/height at CJK break |
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| `0x4ED4E9` | `0x180400` | Preserve an overwide first CJK glyph instead of consuming only its lead byte |
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Layout locals: `esp+0x18..0x1A` character plus NUL, `+0x1B` byte length,
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`+0x14` source byte index, `+0x24` output byte count, `+0x1C` last wrap
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checkpoint. Empty output initializes the checkpoint to `source_index-1`.
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The caves use spare space after the metric table; UVs and atlas pixels are
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unchanged. `tools/test_cjk_layout.py` runs the original layout and measurement
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machine code in Unicorn and captures line bytes and coordinates at the draw
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call boundary. This checks layout behavior without replacing it with a Python
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reimplementation.
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- `tools/add_section.py` — append an executable PE section.
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- `tools/apply_cjk.py` — assemble the caves (keystone), add `.cjk`, write hooks and tables.
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- `tools/build_cjk.py` — build the atlas TGA + `cjk_glyph`/`cjk_metric` from a charset.
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- `tools/make_cn_strings.py` + `tools/cn_strings.py` — GB2312 translation of `Strings.dat`.
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- `tools/install_cjk.py` — deploy/restore everything into the game folder.
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- `tools/decode_dat.py` — decode/encode the XOR `.dat` files.
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- `tools/fontparse.py` — parse `Fonts.dat` into blocks + glyph rects.
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- `tools/xrefs.py`, `tools/disasm.py`, `tools/scan_disp.py` — RE helpers.
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