Difference between revisions of "SCUMM/Technical Reference/Charset resources"

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SCUMM/Technical Reference/Charset resources (view source)

Revision as of 15:15, 26 May 2005

3,694 bytes removed ,  15:15, 26 May 2005
→‎V5/V6 charset format
(V4 format is almost identical to the V5 format)
Line 12: Line 12:
=== V4 charset format ===
=== V4 charset format ===


The header looks as follows:
TODO
 
{| border="1" cellpadding="2" cellspacing="0"
!Size  !! Type            !! Description
|-
|2      ||                || unknown
|-
|15    || bytes          || colour map
|-
|1      || byte            || number of bits per pixel
|-
|3      ||                || unknown
|-
|1024  || 256*quad LE    || character data offsets
|}
 
Character glyphs may be 1, 2, 4 or 8 bits per pixel, and can be masked.
 
The colour map contains the colours each pixel of the character glyph
is drawn as. Pixel value 0 is used for transparency; the other values are
mapped using the color map in the header.
 
The character data pointers contain the offset, relative to the byte
after the end of the colour map (byte 29), of the character data.
This can be 0 if that particular character is not encoded in the character
set. The character data itself is formatted as follows:
 
{| border="1" cellpadding="2" cellspacing="0"
!Size  !! Type            !! Description
|-
|1      || byte            || width of character
|-
|1      || byte            || height of character
|-
|1      || byte            || X offset
|-
|1      || byte            || Y offset
|-
|many    || bytes...        || glyph data bitstream
|}
 
The X and Y offsets are added to the screen coordinates of the top-left
corner of the glyph before drawing. This is useful for, say, shadowed
text. Needless to say, glyphs don't all have to be the same size,
although in all the examples I have they are the same height.
 
The data bitstream encodes the pixels in the glyph in left-to-right,
top-to-bottom order. Multiple pixels are encoded per byte. The pixels
are arranged in big-endian format; so, the first pixel in the stream
is in the top bits of the first data byte; then the bits below that;
and so on. For example, at one bit per pixel:
 
<pre>
Bit position:  7      0 7      0 ...
Words of data: 01234567 89ABCDEF
</pre>
 
At two bits per pixel:
 
<pre>
Bit position:  7      0 7      0 ...
Words of data: 00112233 44556677
</pre>
 
And at four bits per pixel:
 
<pre>
Bit position:  7      0 7      1 ...
Words of data: 00001111 22223333
</pre>


=== V5/V6 charset format ===
=== V5/V6 charset format ===


Like all other resources in V5 and later, the charset data is stored in a chunk, in this case a 'CHAR' chunk. The header looks as follows:
Like all other resources in V5 and later, the charset data is stored in a chunk, in this case a 'CHAR' chunk.  
 
{| border="1" cellpadding="2" cellspacing="0"
{| border="1" cellpadding="2" cellspacing="0"
!Size  !! Type            !! Description
!Size  !! Type            !! Description
Line 92: Line 22:
|8      || chunk tag      || CHAR chunk tag
|8      || chunk tag      || CHAR chunk tag
|-
|-
|6     ||                || unknown
|4      || int (LE)                || unknown, looks like a size field (value is slightly less than the chunk size)
|-
|2     ||                || unknown
|-
|-
|15    || bytes          || colour map
|15    || bytes          || colour map
Line 103: Line 35:
|}
|}


Character glyphs may be 1, 2, 4 or 8 bits per pixel, and can be masked.
The format is otherwise virtually identical to the V4 format, so look at the previous section for further details.
 
The colour map contains the colours each pixel of the character glyph
is drawn as. Pixel value 0 is used for transparency; the other values are
mapped using the color map in the header.
 
The character data pointers contain the offset, relative to the byte
after the end of the colour map (byte 29), of the character data.
This can be 0 if that particular character is not encoded in the character
set. The character data itself is formatted as follows:
 
{| border="1" cellpadding="2" cellspacing="0"
!Size  !! Type            !! Description
|-
|1      || byte            || width of character
|-
|1      || byte            || height of character
|-
|1      || byte            || X offset
|-
|1      || byte            || Y offset
|-
|many    || bytes...        || glyph data bitstream
|}
 
The X and Y offsets are added to the screen coordinates of the top-left
corner of the glyph before drawing. This is useful for, say, shadowed
text. Needless to say, glyphs don't all have to be the same size,
although in all the examples I have they are the same height.
 
The data bitstream encodes the pixels in the glyph in left-to-right,
top-to-bottom order. Multiple pixels are encoded per byte. The pixels
are arranged in big-endian format; so, the first pixel in the stream
is in the top bits of the first data byte; then the bits below that;
and so on. For example, at one bit per pixel:
 
<pre>
Bit position:  7      0 7      0 ...
Words of data: 01234567 89ABCDEF
</pre>
 
At two bits per pixel:
 
<pre>
Bit position:  7      0 7      0 ...
Words of data: 00112233 44556677
</pre>
 
And at four bits per pixel:
 
<pre>
Bit position:  7      0 7      1 ...
Words of data: 00001111 22223333
</pre>


=== NUT (V7 & V8) charset format ===
=== NUT (V7 & V8) charset format ===


TODO
TODO
Fingolfin
1,079

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