Charset - help needed

[Benny]

After messing with Antti's Character Set Viewer I decided to knock up a quick version of my own.

 

The specs as set out in various places are:

 

4 bytes         Header
4 bytes BE      Size
6 bytes         Unknown
15 bytes        Colour Map
1 byte          Bits per pixel
1 byte          Max char height?
1 byte          No chars
1 byte          Unknown

4 bytes * NoChars   Character Offsets
if NoChars=0 then NoChars=256
Character Offsets are relative to the end of the Colour Map data (byte 29)

Individual char data:
1 byte         Char width
1 byte         Char height
1 byte         X offset
1 byte         Y offset
x bits         Data bitstream

 

Thats all fine, but I dont know how to choose the correct colours for the character data. At 1bpp theres 2 possible colours, at 2bpp 4 and at 4bpp 16.

 

I can guess at colour values of course, but I'm unsure as to how the colour values are obtained or how they relate to the colour map. I've got a nasty suspicion that the colours are set in the game scripts and that they specify what colour values go into the colourmap but of course I dont really know.

 

If anyone could explain this to me, or work out the answer from the scummvm source it'd be much appreciated

 

Oh, I'm also unsure what bits map to which colour in the colourmap at 4bpp. I've looked at the ScummVM source for all this, but being ignorant of C++ I couldnt figure it out..

[Scummbuddy]

you may be right about the color being controlled by script. MI2, when Lechuck comes in in Guybrush's dream, he's suspiciously wearing a blue coat, for no reason. Unless I missed something?

[Ender]

Okay.

In the case of a 1BPP image (thru to SCUMM V4), the only colour used is the talkColour set by the script. Yes, this is script controlled.

 

In the case of 2BPP-8BPP fonts (SCUMM5+), the first indexed colour is the talkColour. The others are mapped somehow, I think into the font data itself.

 

map[...] = ??

map[1] = talkColor;

 

(do RLE loop and stuff...)

color = (bits >> (8 - bpp)) & 0xFF;

if (color) {

putPixel(map);

}

(...)

[Benny]

Cheers Endy, I'll have a go at that