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Revision as of 20:10, 11 March 2016

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== Format ==
== Format ==
Note: All measurements are in points.


=== Header ===
=== Header ===
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| u32
| u32
| 4
| 4
| '''Vertical offset'''
| '''Vertical offset''' ''(note: not present in version 1)''
|-
|-
| 0x14
| 0x14
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|-
|-
| 0x18
| 0x18
| bool
| 1
| {{unknown|'''Unknown'''}}
|-
| 0x19
| bool
| 1
| {{unknown|'''Unknown'''}}
|-
| 0x1A
| u32
| u32
| 4
| 4
| {{unknown|'''Unknown'''}} ''(note: not present in version 1)''
| {{unknown|'''Unknown'''}}  
|-
| 0x1C
| u16
| 2
| {{unknown|'''Unknown'''}}
|-
|-
| 0x1E
| 0x1E
| u32
| u32
| 4
| 4
| '''Font size''' (in points)
| '''Font size'''
|-
|-
| 0x22
| 0x22
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| u32
| u32
| 4
| 4
| {{unknown|'''Unknown'''}}
| '''Texture format''' (see [[#Textures|Textures]])
|-
|-
| -
| -
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| 4
| 4
| '''Glyph count'''
| '''Glyph count'''
|-
| -
| Glyph[]
| -
| '''Glyph table''' ([[#Glyph Entry (Version 2)|Version 2]], [[#Glyph Entry (Version 4)|Version 4]])
|}
|}


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The kerning index value is the index of the first kerning table entry for the given character. Since the table is sorted in alphabetical order, this can be used to speed up lookup time.
The kerning index value is the index of the first kerning table entry for the given character. Since the table is sorted in alphabetical order, this can be used to speed up lookup time.


This section of the file changes somewhat from version 2 to 4. Starting in version 4, glyphs are able to be encoded to only one particular RGBA channel, which allows multiple glyphs to be encoded in the same space on the texture. A "channel index" value was introduced to track which channel the glyph is on. Additionally, a lot of 32-bit values were reduced to 8- or 16-bit. Aside from that, though, the actual layout is still the same, with the same values in the same places.
This section of the file changes somewhat from version 2 to 4. Starting in version 4, font textures are able to be split up into multiple layers, which allows multiple glyphs to be encoded in the same space on the texture. A "layer index" value was introduced to track which layer the glyph is on. Additionally, a lot of 32-bit values were reduced to 8- or 16-bit. Aside from that, though, the actual layout is still the same, with the same values in the same places.


==== Version 2 (Metroid Prime NTSC) ====
==== Version 2 (Metroid Prime NTSC) ====
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| u32
| u32
| 4
| 4
| '''Kerning index'''
| '''Kerning start index'''
|-
|-
| 0x2E
| 0x2E
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|}
|}


==== Version 4 (Metroid Prime PAL) ====
==== Version 4 (Metroid Prime PAL/Trilogy) ====


{| class="wikitable"
{| class="wikitable"
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| u8
| u8
| 1
| 1
| '''RGBA channel index'''
| '''Layer index'''
|-
|-
| 0x13
| 0x13
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|-
|-
| 0x18
| 0x18
| u8
| 1
| '''Vertical offset'''
|-
| 0x19
| u16
| u16
| 2
| 2
| '''Kerning index'''
| '''Kerning start index'''
|-
|-
| 0x1A
| 0x1B
| colspan=3 {{unknown|End of glyph definition}}
| colspan=3 {{unknown|End of glyph definition}}
|}
|}
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=== Kerning Table ===
=== Kerning Table ===


This table is at the end of the file, and defines kerning pairs. The table is case-sensitively sorted in alphabetical order, which allows for fast lookup times using the glyph kerning indices. After a 32-bit count value, each pair follows this simple structure:
This table is at the end of the file, and defines kerning pairs. Kerning pairs horizontally adjust the second character of the pair whenever that particular sequence of characters is encountered. The table is case-sensitively sorted in alphabetical order, which allows for fast lookup times using the glyph kerning indices. After a 32-bit count value, each pair follows this simple structure:


{| class="wikitable"
{| class="wikitable"
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| 0x8
| 0x8
| colspan=2 {{unknown|End of entry}}
| colspan=2 {{unknown|End of entry}}
|}
== Textures ==
{{research|minor|Someone should look at the code to make sure the info in this section is accurate.}}
Textures used by FONT files are encoded in a bit of an unorthodox manner. The font format allows for multiple glyphs to be encoded in the same spot on the texture by splitting up the texture into multiple layers. The way this is handled on the textures is by encoding the textures with palettes (as C4), but modifying the palette indices at runtime and loading each layer one at a time as a separate texture. Each bit of the palette index corresponds to a layer, so up to four layers per font are supported. The MSB refers to layer 0, while the LSB refers to layer 3. In DKCR, font textures are encoded as C8, so theoretically the game could use up to eight layers per font; however, it still never actually uses more than four.
The texture format is determined by a value in the header. These are the possible settings:
{| class="wikitable"
! Value
! Description
! V1
! V2
! V4
! V5
|-
| 0
| One glyph layer, no outlines; fill on layer 0
| {{check}}
| {{check}}
| {{check}}
| {{check}}
|-
| 1
| One glyph layer, with outlines; fill on layer 0, outline on layer 1
| {{check}}
| {{check}}
| {{check}}
| {{check}}
|-
| 2
| Four glyph layers, no outlines
| {{nocheck}}
| {{nocheck}}
| {{check}}
| {{check}}
|-
| 3
| Two glyph layers, with outlines; fill on layers 0/2, outlines on layers 1/3
| {{nocheck}}
| {{nocheck}}
| {{check}}
| {{check}}
|-
| 4
| Two glyph layers, no outlines; copies on layers 0/1, and layers 2/3
| {{nocheck}}
| {{nocheck}}
| {{check}}
| {{check}}
|-
| 8
| Two glyph layers, with outlines; fill on layers 2/3, outlines on layers 0/1
| {{nocheck}}
| {{nocheck}}
| {{nocheck}}
| {{check}}
|}
To dump out every layer into a single texture by encoding each layer on a separate RGBA channel, the following palette colors could be substituted into the texture:
{| class="wikitable"
! Index
! Binary
! Color
! Description
|-
| 0
| 0000
| 0x8000
| None
|-
| 1
| 0001
| 0x7000
| Alpha
|-
| 2
| 0010
| 0xFC00
| Blue
|-
| 3
| 0011
| 0x7F00
| Blue/Alpha
|-
| 4
| 0100
| 0x83E0
| Green
|-
| 5
| 0101
| 0x70F0
| Green/Alpha
|-
| 6
| 0110
| 0xFFE0
| Green/Blue
|-
| 7
| 0111
| 0x7FF0
| Green/Blue/Alpha
|-
| 8
| 1000
| 0x801F
| Red
|-
| 9
| 1001
| 0x700F
| Red/Alpha
|-
| 10
| 1010
| 0xFC1F
| Red/Blue
|-
| 11
| 1011
| 0x7F0F
| Red/Blue/Alpha
|-
| 12
| 1100
| 0x83FF
| Red/Green
|-
| 13
| 1101
| 0x70FF
| Red/Green/Alpha
|-
| 14
| 1110
| 0xFFFF
| Red/Green/Blue
|-
| 15
| 1111
| 0x7FFF
| Red/Green/Blue/Alpha
|}
|}


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