First pass at displaying Menu files

doc/formats/mnu.md

@@ -1,6 +1,129 @@
 # *.mnu
 
 These files appear to be the UI definitions for Chaos Gate. Some relate to
-system menus, other to in-game menus.
+system menus, other to in-game menus. Their names are hardcoded into the
+`WH40K.exe` binary. Each has a `.obj` file associated with it.
+
+It's an ASCII-formatted text file with a 12-line header, followed by a number
+of descriptor records.
+
+Here's the top of `MainGame.mnu`:
+
+```
+MainGame.obj
+BACKGROUND COLOR 0..255..-1 trans : 0
+HYPERTEXT COLOR 0..255            : 120
+FONT TYPE 0..5                    : 10
+wh40k_12
+basfnt12
+wh40k_47
+wh40k_12_red
+wh40k_12_blue
+wh40k_12_green
+wh40k_12_yellow
+NULL
+```
+
+The first line of the header is a `.obj` file containing sprites we want to
+display on-screen. We see entries further down have a `SPRITEID`, which must
+reference entries in that file.
+
+In `SaveGame.mnu`, we can see multiple `.obj` files can be referenced.
+
+There are then 3 lines that seem to be fixed descriptor names with values
+that vary. Is this font colour, perhaps? Unsure.
+
+Next is a variable-length list of font names, referencing files in the `Fonts`
+directory.
+
+Finally, there's a list of records that specify the menu itself. Truncated
+contents of `SaveGame.mnu`:
+
+```
+#rem..........Background
+MENUID     : 1
+MENUTYPE   : 0
+MOVEABLE   : 0
+ACTIVE     : 1
+SPRITEID   : 0
+ACCELERATOR: 0
+DRAW TYPE  : 0
+SHARE      : -1
+X-CORD     : -1
+Y-CORD     : -1
+DESC       :
+*
+#rem..........MAIN BACKGROUND
+MENUID     : 2
+MENUTYPE   : 45
+MOVEABLE   : 0
+ACTIVE     : 1
+SPRITEID   : 0
+ACCELERATOR: 0
+DRAW TYPE  : 0
+SHARE      : -1
+X-CORD     : -1
+Y-CORD     : -1
+DESC       :
+#rem.......... MAIN BACKGROUND
+        SUBMENUID  : 1
+        SUBMENUTYPE: 31
+        FONTTYPE   : 20
+        ACTIVE     : 0
+        SPRITEID   : -1
+        ACCELERATOR: 0
+        DRAW TYPE  : 0
+        SHARE      : 0
+        SOUNDTYPE  : 0
+        DESC       :
+*
+#rem..........Chat List Box Menu
+MENUID     : 21
+MENUTYPE   : 1
+MOVEABLE   : 0
+ACTIVE     : 1
+SPRITEID   : 764
+ACCELERATOR: 0
+DRAW TYPE  : 0
+SHARE      : -1
+X-CORD     : -1
+Y-CORD     : -1
+DESC       :
+[...]
+*
+~
+```
+
+We start processing these as soon as we see `MENUID`, I suppose. Each toplevel
+item is `*`-delimited, and the list is terminated with `~`.
+
+Each menu has a list of parameters:
+
+|---------|----------|---------|
+| Name    | Examples | Purpose |
+|---------|----------|---------|
+| `MENUID`|  `1`, `2`, `3` | Maybe linking between menus? |
+| `MENUTYPE` | `0`, `1`, `2`, `3`, `45`, `300` | ? |
+| `MOVEABLE` | `0` | Unimplemented functionality? |
+| `ACTIVE` | `0`, `1` | Boolean - whether to show the thing |
+| `SPRITEID` | `-1`, `0`, `123` | Select from `.obj` file |
+| `ACCELERATOR` | | |
+| `DRAW TYPE` | | |
+| `SHARE` | | |
+| `X-CORD` | | |
+| `Y-CORD` | | |
+| `FONTTYPE` | | |
+| `SOUNDTYPE` | | |
+| `DESC` | | |
+
+
+Submenus also show a couple of unique values:
+
+|------|----------|---------|
+| Name | Examples | Purpose |
+|------|----------|---------|
+| `SUBMENUID` | | |
+| `SUBMENUTYPE` | | |
+