Subversion Repositories Games.Prince of Persia

### What is the difference between autocontrol, control and anim?

Autocontrol: where keypresses are generated. (guards, demo)

Control: where sequences are activated based on keystrokes and other things.

Anim: where sequences are interpreted.

### What is the difference between frame, image and resource?

frame: An index into the frame table.

	Also an unit of time = 1/12 seconds. (1/10 s when fighting.)

image: 0-based index within a chtab

resource: ID in DAT file, image + palette_resource_id + 1

### What is a chtab?

It's a collection of images, with a common palette.

The game uses these chtabs:

0: sword (in someone's hand) (PRINCE, 700)

1: flame, sword (on floor), potion (PRINCE, 150)

2: kid (KID, 400)

3: princess in intro (PV, 800)

4: Jaffar in intro (PV, 850), princess in cutscenes (PV, 900)

5: guard (GUARD/SKEL/FAT/SHADOW/VIZIER, 750)

6: environment (except wall) (VDUNGEON/VPALACE, 200)

7: environment wall (VDUNGEON/VPALACE, 360)

8: princess room (PV, 950)

9: princess bed (PV, 980)

### What tables are there?

seqtbl[]: contains the sequence codes

seqtbl_offsets[]: contains the offsets (addresses) of the various sequences

frame_table_kid[]: contains the data of the kid's frames

frame_tbl_guard[]: contains the data of the guards' frames

frame_tbl_cuts[]: contains the data of the cutscenes' frames (princess, Jaffar)

sword_tbl[]: contains the data of the sword's frames

### What's in the frame tables?

(used in load_frame())

For each frame:

image

	0-based index

sword

	bits 0..5: sword frame (0-based index into the sword table)

	bits 6..7: chtab (add 2: 00=2, 01=3, 10=4, 11=5)

dx

	delta x from char's position to image's position (+ = forward)

dy

	delta y from char's position to image's position (+ = down)

flags

	bits 0..4: x-position of weight (backward, that is right on the image)

	bit 5: "thin" this frame for collision detection (used in set_char_collision())

	bit 6: needs floor (used in check_on_floor() and check_press())

	bit 7: even/odd pixel (used in load_frame_to_obj())

### What's in the sequence table?

The sequence table is a list of frame indexes and commands.

sequence codes: (used in play_seq())

0x00..0xF0: show frame with this index

0xF1: end level

0xF2 n: play sound

0xF3 n: get item if n=1

0xF4: knock down (loose floors will shake in char's row)

0xF5: knock up (loose floors will shake in row above char's row)

0xF6: nothing

0xF7 l h: jump to hl if slow-fall is active

0xF8 x y: set falling speed (x: + = forward, y: + = down)

0xF9 n: set action

0xFA y: move y pixels (+ = down)

0xFB x: move x pixels (+ = forward)

0xFC: go down one row (does not change y coordinate)

0xFD: go up one row (does not change y coordinate)

0xFE: flip

0xFF l h: jump to hl

### What's in the sequence offset table?

sequence indexes:

See internals_sequence-index.csv

### How are images drawn at given coordinates?

Coordinates give the bottom left of the image.

For flipped images, it's the bottom right of the flipped image.

### How are x coordinates counted?

Char:

58=left

198=right

one tile is 14 units wide

|

|load_frame_to_obj()

V

Object:

0=left

280=right

one tile is 28 units wide

|

|calc_screen_x_coord()

V

Screen:

0=left

320=right

one tile is 32 units wide

### What is stored about characters?

(struct char_type)

frame

	Index of current frame.

	The used frame table depends on charid.

x

	x-position in the Char coordinate system.

y

	y-position

direction

	0x00 (>=0): right (image is flipped)

	0x56: none (for guards)

	0xFF (<0): left (image is not flipped)

curr_col

	Current column, 0..9 is in the current room.

curr_row

	Current row, 0..2 is in the current room.

action

	0: stand

	1: run, jump

	2: hang, climb

	3: in midair

	4: in freefall

	5: bumped

	6: hang straight

	7: turn

	99: char is hurt by sword

fall_x

	x-speed of falling (+ = forward)

fall_y

	y-speed of falling (+ = down)

room

	Current room.

repeat

	(used in safe_step())

	0: may step off edge

	1: won't step off edge

charid

	Who is this?

	Its value decides which frame table to use (in load_frame()), and various things about char's behaviour.

	0: kid

	1: shadow

	2: guard

	4: skeleton

	5: princess

	6: vizier (in intro)

	0x18: mouse

sword

	0: not holding sword

	2: holding sword

alive

	<0: is alive

	>=0: is dead

curr_seq

	Current position (address) in the sequence table.