Animations

Relevant files:

anim.mul

anim.idx

animdata.mul

animinfo.mul

In the animations files all data regarding animated creatures are saved.

anim.idx holds the index offests for anim.mul are stored.
If you want to read an animation sequence you first look into anim.idx reading the offset and then go to anim.mul reading the data. anim.idx also contains the size of the data to read allowing to read in whole relevant chunk at once saving a lot of performance on file-IO.

anim.mul contains a set of frames holding the animation sequences.

The contents of animdata.mul and animinfo.mul are completely unkown!
If you know something about these files, please tell!

anim.idx

This file contains the indexes and to anim.mul.
It's structured into groups of 12 bytes.
To load an animation sequence with a specific ID, search for ID * 12 in this file, to get the correct index.

Index Record (12 bytes):

0	1	2	3	4	5	6	7	8	9	A	B
index				size				unkown

Finding the animation ID

A thing wich is still rather in darkness is how to acquire the correct frame id for an animation sequence.

Well first of there are three different kinds of creatures:

High detail creatures (monsters)
Low detail creatures (animals)
Humans and their equipment.

High detail creatures and humans have 10 frames per sequence, while low detail creatures have only 5.

Each creature has it's creature ID like in example 0x01 for the orc. 0x3b for the beloved red dragon, or 0x190 which is a man. So now the get it a little clearer.

The animations are first separated into creatures.
Each creature is separated into it's states, like walking, standing, running, fighting etc.
An each state has 5 directions: down, south, left, west and up.
The missing directions north, right and east have to calculated by simply mirroring the corresponding direction.

So if you want to find the animation id of an id, you first have to determine it's type:

Creature ID range (cID)	Type	Sequences/ creature	Calculates into animation ID (aID)
0x000 - 0x0c7	High detail	110	aID = cID * 110
0x0c8 - 0x18F	Low detail	65	aID = (cID - 0xc8) * 65 + 22000
0x190 -	Human & Equipment	175	aID = (cID - 0x190) * 175 + 35000

After that the type multiplied by 5 is added to to aID.
Which types (running,walking etc.) correspond exactly to which numbers is yet unkown.

Finally add the direction to aID. (See arachnide's compass as soon I get to design it :o)

Down	+0
South	+1
Left	+2
North	+3
Up	+4

anim.mul

So finally the animation sequence id is known, the index has been looked up in anim.idx, let's start to actually reading in some sprites!

The sequence starts with a 512 byte palette of 256 colors.
Not hard to guess each color in later context is an index to this palette. Followed are the number of frames in this sequence, and a table of offsets for each frame.

Animation Squence:

UNSIGNED INT16[256]	The palette
UNSIGNED INT32	Frame count
UNSIGNED INT32[Frame count]	Frame offsets
...	The frame data

A Frame:

Seek from the end of the palette plus the offset from the offset table to find the start of the frame:
SIGNED INT16	Image center X
SIGNED INT16	Image center Y
UNSIGNED INT16	Width
UNSIGNED INT16	Height
...	...data..

The data stream:
The data is organized into "run's" of pixels.
If you have a picture, it will go from top to bottom, telling where the foreground starts and how many pixels the line extends to the right, until it reaches background again.
Each pixel-run is constructed following way:

UNSIGNED INT16	RowHeader
SIGNED INT16	RowOffset
...	...data..

If either RowHeader ir RowOffset equals 0x7FFF it is the end of the data stream, and the picture is complete.
RowHeader and RowOffset are both bit-mapped:

RowHeader:

0	1	2	3	4	5	6	7	8	9	A	B	C	D	E	F
line number				runby

RowOffset:

0	1	2	3	4	5	6	7	8	9	A	B	C	D	E	F
+/-	x-offset									unkown

ATTENTION: to get the x-offset of the pixel-run you'll have to to shift right by 6. However you have to respect to sign! Either do it with the inline assembler command shr like Alazane did. (shift right/respect sign), or write it out like Arachnide prefers to:

int xoffs = (rowOffset) >> 6;
if (rowOffset & 0x8000) {
  xoffs += centerx - 1024;
} else {
  xoffs += centerx;
}

Add center X to x-offset (already happened in above code snippet).

Okay now linenumber, offset and how many pixels read in are known. Nobody is gonna stop now!
Read in runby number of bytes, look them up in the palette, and put them at the position (linenumber) / (offset + x) in the sprite.
- finished, Hope I got it all clear!