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.RDT (Resident Evil 2)

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Patrice Mandin edited this page Aug 27, 2021 · 19 revisions

Table of Contents

Games

The .RDT file format is used to stored the description of a room in Resident Evil 2. It should contain the camera position (to correctly display 3D objects), the background images and sprites used to draw the scene, description of when to change camera, position of enemies when entering room, and so on...

Structure

The values are stored in Little-Endian order.

The file is always named roomSXXP.rdt. 'S' is the game status/stage. 'XX' is the location number. 'P' is the player number (0 for Leon, 1 for Claire).

Header

A RDT file starts with a 8-byte array, to store count for different objects. 

typedef struct {
  char unknown0;
  char num_object7; /* Number of objects at offset 7, seems to be number of cameras of the room */
  char num_object10; /* Number of objects at offset 10 */
  char unknown3;
  char unknown4;
  char unknown5;
  char unknown6;
  char unknown7;
} rdt_header_t;

Object list

Following the header lies an array of offsets to objects in file. 

Offset 0: unknown
Offset 1: embedded VAB file
Offset 2-6: unknown
Offset 7: camera positions for each image, background image masks.
Offset 8: camera switches
Offset 9: lights
Offset 10: info about embedded TIM files
Offset 11-12: unknown
Offset 13: encoded text for stuff you can examine, japanese language?
Offset 14: encoded text for stuff you can examine, western language?
Offset 15: unknown
Offset 16: Initialization script
Offset 17: Execution script
Offset 18: sprites description in embedded TIM file (offset 20)
Offset 19: unknown
Offset 20: list of embedded TIM files (sprites to display on background image)
Offset 21: another set of TIM files (or this offset=length of file if not present)
Offset 22: unknown (0 if not present)

Offset 0

Its length is always 192 bytes. It's an array of 48 elements: 

typedef struct {
  short unknown0; /* Always 0xffff or 0 */
  short unknown1; /* 0xffff if unknown0=0xffff, or something else otherwise */
} rdt_offset0elt_t;

Offset 1

The embedded VAB file is a sound bank. Either it is the one for the background music for the room, or the sounds needed for various effects (fire, puzzles, triggers and the like).

Offset 6

First there is this structure, used as header: 

typedef struct {
  unsigned long unknown0;
  unsigned long count; /* Number of elements+1 in array following, i.e 16 here means 15 elements */
  unsigned short unknown1;
  unsigned short constant0; /* Seems always 0xffff */
  unsigned long constant1; /* Seems always 0xc5c5c5c5 */
} rdt_offset6_t;

Then follows an array of elements with following structure: 

typedef struct {
  short unknown0;
  short unknown1;
  unsigned short unknown2;
  unsigned short unknown3;
  unsigned short unknown4;
  unsigned short unknown5;
  unsigned long unknown6;
} rdt_offset6elt_t;

Offset 7, camera positions

This array has the same number of items, as the number of images for a room.

This is an array of the following structures: 

typedef struct {
	unsigned short unknown0;
	unsigned short const0;	/* 0x683c, or 0x73b7 */
	long camera_from_x;	/* Position of the camera */
	long camera_from_y;
	long camera_from_z;
	long camera_to_x;	/* Where the camera is looking to */
	long camera_to_y;
	long camera_to_z;
	unsigned long masks_offset;	/* Offset to background image masks in the file, see below */
					/* 0xffffffff if no masking */
} rdt_camera_pos_t;

Image masks

The masks_offset is an offset to an extra structure, which has following header: 

typedef struct {
	unsigned short count_offsets;	/* Number of global offsets, or 0xffff for none */
	unsigned short count_masks;	/* Number of masks, or 0xffff for none */
} rdt_masks_t;

Then you have 'rdt_mask_offset_t' items, which have a 8-byte length. Summing all 'count' fields should equal the 'count_masks' of the rdt_masks_t structure. 

typedef struct {
	unsigned short count;	/* Number of masks, with which to use this structure */
	unsigned short unknown;
	unsigned short dst_x;	/* Destination position on background image/screen, to be added */
	unsigned short dst_y;
} rdt_mask_offset_t;

And then you have 'rdt_[rect|square]_mask_t' items, which have either 12-byte (rectangular mask) or 8-byte length (square mask). The length is 12 if bytes 6-7 (rdt_square_mask_t.size field) are zero, and 8 otherwise. The 'depth' value is the Z distance of the mask from the camera (low value=near, high value=far). 

typedef struct {
	unsigned char src_x;	/* Source position in common/objspr/rsRXXP.adt image file */
	unsigned char src_y;
	unsigned char dst_x;	/* Destination position on background image/screen */
	unsigned char dst_y;
	unsigned short depth;	/* Distance/32 from camera */
	unsigned short zero;
	unsigned short width, height;	/* Dimensions of mask */
} rdt_rect_mask_t;

Offset 8, camera switches

This array has a variable length. The list is terminated with 0xffffffff value for the first 4 bytes of the structure. It contains a description of a zone in 3D space, where you switch from one camera to the other when the player crosses it.

The first zone listed for a camera switch, with cam1=0 has a different purpose, and must be ignored for a camera switch. For example, you can have two (1,0,...) zones listed for a cam switch from 1 to 0. Only the second is the real camera switch. 

typedef struct {
  unsigned short const0; /* 0xff01 */
  unsigned char cam0;
  unsigned char cam1;
  short x1,y1; /* Coordinates to use to calc when player crosses switch zone */
  short x2,y2;
  short x3,y3;
  short x4,y4;
} rdt_camera_switch_t;

Offset 9, lights

Up to 3 lights can be defined for each camera. The first 2 are stored in the file, and the remaining one can be defined in-game by the game scripts. 

typedef struct {
	short x,y,z;
} rdt_light_pos_t;

typedef struct {
	unsigned short light_type[2];
	rdt_light_color_t colors[3];	/* Color for each light */
	rdt_light_color_t ambient;	/* Ambient color for camera */
	rdt_light_pos_t positions[3];	/* Position for each light */
	unsigned short brightness[3];	/* Brightness for each light */
} rdt_light_t;

rdt_light_t lights[num_cameras];

Offset 10

This structure is only present if the count byte for it in the header of the file is non zero. It is a array of the following structure: 

typedef struct {
  unsigned long tim_offset;
  unsigned long unk_offset;
} rdt_offset10_t;

The tim_offset is an offset in the file to an embedded TIM image. The other is an offset to an unknown structure

Offset 11

First, there is an 'unsigned short' which is the number of items in the array that follows: 

typedef struct {
  short unknown0[6];
} rdt_offset11elt_t;

Offset 12

First, there is an unsigned long, which is the number of elements in the array that follows it: 

typedef struct {
  unsigned long unknown0;
  short unknown1[4];
} rdt_offset12elt_t;

Offset 13, Texts (Language 1)

First, you have an arrays of 'unsigned short', which are relative offsets to the beginning of this object. So the number of items is the first offset/2 (if we are lucky that the first offset always has the lowest value).

It contains the texts for cutscenes, dialogs, examining objects. Japanese text is stored at this offset (when available), else it contains the Western language text (and offset 14 is 0 in this case, thus meaning no text).

Offset 14, Texts (Language 2)

Same structure as offset 13.

This time, it holds the encoded text in some Western language (if the one in offset 13 contains the Japanese texts).

Conversion table, from byte to ASCII value: 

0x00-0x0f: " .___()_____0123"
0x10-0x1f: "456789:_,"!?_ABC"
0x20-0x2f: "DEFGHIJKLMNOPQRS"
0x30-0x3f: "TUVWXYZ[/]'-_abc"
0x40-0x4f: "defghijklmnopqrs"
0x50-0x5f: "tuvwxyz_________"

Note: not all characters have been found (i.e. the ones with '_'). Codes above 0x57 may also be different given the language, for characters with trema, accents and the like. There are also some formatting codes: 

0xf3: ?
0xfa: start text, followed by an unknown byte
0xfb: Yes/No question
0xfc: carriage return
0xfd: ?, followed by unknown byte
0xfe: end text

You can see the extra special characters in the file common/datu/font0.adt or common/datu/font0.tim.

Offset 16, initialization script for room

This is the initialization script for the room. It starts with an array of unsigned long, giving offset to each function of the script. Thus, the first offset listed / 2 gives you the number of functions in the script. Then follows the script, in bytecode-style.

0x00-0x0f

Byte Instruction Length Description
0x00 Nop _ NO Operation. 
      Mostly used to align next instruction on even offset.
    

typedef struct {
	Uint8	opcode;
} script_inst_nop_t;
0x01 Evt_end _ Exit current function and return a value. 
typedef struct {
	Uint8	opcode;
	Uint8	ret_value;
} script_inst_evt_end_t;
0x02 Evt_next _ Wait for any player input (for example to answer a Yes/No question), before executing further script instructions. 
typedef struct {
	Uint8	opcode;
} script_inst_evt_next_t;
0x03 Evt_chain _ Reinitialize script execution data before executing new function ? 
typedef struct {
	Uint8	opcode;
	Uint8	unknown0;
	Uint8	unknown1;
	Uint8	event;
} script_inst_evt_chain_t;
0x04 Evt_exec _ 
      This instruction will execute the embedded two-byte instruction if the condition is true.
      When condition is 0xff, instruction is executed whenever there is a camera switch.
      Several instructions can be defined to be called when condition is true.
    

typedef struct {
	Uint8	opcode;
	Uint8	cond;
	Uint8	ex_opcode;
	Uint8	event;
} script_inst_evt_exec_t;
0x05 Evt_kill _
  • MAYBE* Disable an event.
typedef struct {
	Uint8	opcode;
	Uint8	event;
} script_inst_evt_kill_t;
0x06 Ifel_ck _ IF block instruction start. 
      Any following Ck instruction evaluated to FALSE will end this block.
    

typedef struct {
	Uint8	opcode;
	Uint8	dummy;
	Uint16	block_length;
} script_inst_ifel_ck_t;
0x07 Else_ck _ ELSE block instruction start. 
      Block to execute if precedent IF block must be stopped if some condition evaluated to FALSE.
      Note: it's either IF/ENDIF, or IF/ELSE; there is no IF/ELSE/ENDIF sequence.
    

typedef struct {
	Uint8	opcode;
	Uint8	dummy;
	Uint16	block_length;
} script_inst_else_ck_t;
0x08 Endif _ IF block instruction end. 
      Exit current IF instruction block.
    

typedef struct {
	Uint8	opcode;
} script_inst_endif_t;
0x09 Sleep _ Initialize Sleep. 
      In the bytecode, you will find bytes 09 0a NN NN,
      and the script will only add 1 to current bytecode position for instruction 0x09,
      to get to instruction 0x0a, and process the sleep loop.
    

typedef struct {
	Uint8	opcode;
	Uint8	dummy;
	Uint16	count;
} script_inst_sleep_t;
0x0a Sleeping _ Execute Sleep. 
      Current event instructions will not be executed for the duration of sleep.
    

typedef struct {
	Uint8	opcode;
	Uint8	count_lo;
	Uint8	count_hi;
} script_inst_sleeping_t;
0x0b Wsleep _
  • MAYBE* Initialize global sleep.
typedef struct {
	Uint8	opcode;
} script_inst_wsleep_t;
0x0c Wsleeping _
  • MAYBE* Execute global sleep.
      All events instructions will not be executed for the duration of sleep.
    

typedef struct {
	Uint8	opcode;
} script_inst_wsleeping_t;
0x0d For _ Initialize FOR loop. 
      Execute a block of instructions 'count' times.
    

typedef struct {
	Uint8	opcode;
	Uint8	dummy;
	Uint16	block_length;
	Uint16	count;
} script_inst_for_t;
0x0e Next _ End of FOR block. 
typedef struct {
	Uint8	opcode;
	Uint8	dummy;
} script_inst_next_t;
0x0f While _ Start of WHILE block. Execute a block of instructions unless a following Ck condition is evaluated to FALSE. 
typedef struct {
	Uint8	opcode;
	Uint8	dummy;
	Uint16	block_length;
} script_inst_while_t;

0x10-0x1f

Byte Instruction Length Description
0x10 Ewhile _ End of WHILE block. 
typedef struct {
	Uint8	opcode;
	Uint8	dummy;
} script_inst_ewhile_t;
0x11 Do _ Start of DO block. 
      Execute a block of instructions (condition at end of block).
    

typedef struct {
	Uint8	opcode;
	Uint8	dummy;
	Uint16	block_length;
} script_inst_do_t;
0x12 Edwhile _ End of DO block. 
      Execute the block of instructions as long as the following Ck condition(s) are evaluated to TRUE.
    

typedef struct {
	Uint8	opcode;
	Uint8	block_length;
} script_inst_edwhile_t;
0x13 Switch _ Start of SWITCH block. 
      Execute a block of instructions depending on the value of 'varw' variable.
    

typedef struct {
	Uint8	opcode;
	Uint8	varw;
	Uint16	block_length;
} script_inst_switch_t;
0x14 Case _ Start of CASE block. 
      Execute a block of instructions if 'varw' variable of Switch instruction equals 'value'.
    

typedef struct {
	Uint8	opcode;
	Uint8	dummy;
	Uint16	block_length;
	Uint16	value;
} script_inst_case_t;
0x15 Default _ Start of DEFAULT block. 
      Execute a block of instructions if none of preceding Case instructions matches.
    

typedef struct {
	Uint8	opcode;
	Uint8	dummy;
} script_inst_default_t;
0x16 Eswitch _ End of SWITCH block. 
typedef struct {
	Uint8	opcode;
	Uint8	dummy;
} script_inst_eswitch_t;
0x17 Goto _ Jump to another instruction in current event. 
      'rel_offset' is relative to start of this instruction.
    

typedef struct {
	Uint8	opcode;
	Uint8	unknown0;
	Uint8	unknown1;
	Uint8	unknown2;
	Sint16	rel_offset;
} script_inst_goto_t;
0x18 Gosub _ Execute a subroutine for this event. 
typedef struct {
	Uint8	opcode;
	Uint8	event;
} script_inst_gosub_t;
0x19 Return _ End a subroutine called with Gosub. 
typedef struct {
	Uint8	opcode;
	Uint8	dummy;
} script_inst_return_t;
0x1a Break _ Exit a currently executing block (For, Case, Do, etc). 
typedef struct {
	Uint8	opcode;
	Uint8	dummy;
} script_inst_break_t;
0x1b For2 _ 
typedef struct {
	Uint8	opcode;
	Uint8	unknown0;
	Uint16	unknown1;
	Uint16	unknown2;
} script_inst_for2_t;
0x1c Break_point _ 
typedef struct {
	Uint8	opcode;
} script_inst_break_point_t;
0x1d Work_copy _ Change instruction by writing value inside script. 
      'varw' is the variable we want to write at offset 'offset' (relative to start of next instruction).
      'size' tells if we write a byte or a word.
    

typedef struct {
	Uint8	opcode;
	Uint8	varw;
	Uint8	offset;
	Uint8	size;
} script_inst_work_copy_t;
0x1e Nop1E _ 
typedef struct {
	Uint8	opcode;
} script_inst_nop1e_t;
0x1f Nop1F _ 
typedef struct {
	Uint8	opcode;
} script_inst_nop1f_t;

0x20-0x2f

Byte Instruction Length Description
0x20 Nop 1
0x21 Ck 4 
typedef struct {
	unsigned char opcode;	/* 0x21 */
	unsigned char bit_array;	/* Index of array of bits to use (see end of section) */
	unsigned char number;	/* Bit number to check */
	unsigned char value;	/* Value to compare (0 or 1) */
} script_bittest_t;
Test bit in array.
0x22 Set 4 
typedef struct {
	unsigned char opcode;	/* 0x22 */
	unsigned char bit_array;	/* Index of array of bits to use (see end of section) */
	unsigned char number;	/* Bit number to check */
	unsigned char op_chg;	/* Operation on bit */
				/* 0x00: CLEAR */
				/* 0x01: SET */
				/* 0x02-0x06: INVALID */
				/* 0x07: CHANGE */
} script_bitchg_t;
Change bit in array.
0x23 Cmp 6 
typedef struct {
	unsigned char opcode; /* 0x23 */
	unsigned char dummy;
	unsigned char index;	/* Index in array */
	unsigned char compare;	/* Compare function */
				/* 0: EQ */
				/* 1: GT */
				/* 2: GE */
				/* 3: LT */
				/* 4: LE */
				/* 5: NE */
				/* 6: ? */
	short value;	/* Value to compare against */
} script_cmp_varw_t;
Compare a value against one in an internal array.
0x24 Save 4 
typedef struct {
	unsigned char opcode;	/* 0x24 */
	unsigned char index;	/* Index of source variable */
	short value;	/* New value of variable */
} script_set_varw_t;
Set a value for variable.
0x25 Copy 3 
typedef struct {
	unsigned char opcode;	/* 0x25 */
	unsigned char dst;	/* Index of destination variable */
	unsigned char src;	/* Index of source variable */
} script_copy_varw_t;
Copy a word from source variable to destination variable
0x26 Calc 6 
typedef struct {
	unsigned char opcode;	/* 0x26 */
	unsigned char dummy;
	unsigned char op;	/* 0x00: ADD, 0x01:SUB, 0x02:MUL, 0x03:DIV */
				/* 0x04: MOD, 0x05:OR, 0x06:AND, 0x07:XOR */
				/* 0x08: NOT, 0x09:LSL, 0x0a:LSR, 0x0b:ASR */
	unsigned char varw;	/* Index of variable */
	short value;	/* Parameter for operation */
} script_op_varw_imm_t;
Operation on a variable, using immediate value.
0x27 Calc2 4 
typedef struct {
	unsigned char opcode;	/* 0x27 */
	unsigned char op;	/* 0x00: ADD, 0x01:SUB, 0x02:MUL, 0x03:DIV */
				/* 0x04: MOD, 0x05:OR, 0x06:AND, 0x07:XOR */
				/* 0x08: NOT, 0x09:LSL, 0x0a:LSR, 0x0b:ASR */
	unsigned char varw;	/* Index of variable */
	unsigned char srcw;	/* Variable to use as parameter for operation */
} script_op_varw_t;
Operation on a variable, using other variable as parameter.
0x28 Sce_rnd 1
0x29 Cut_chg 2 
typedef struct {
	unsigned char opcode;	/* 0x29 */
	unsigned char id;	/* Set active camera */
} script_cam_set_t;
0x2a Cut_old 1
0x2b Message_on 6 
typedef struct {
	unsigned char opcode; /* 0x2b */
	unsigned char unknown0;
	unsigned char id; /* Text number to display (from offset 13 or 14 of RDT file) */
	unsigned char unknown1[3];
} script_print_t;
0x2c Aot_set 20 Non pickable object (Obstacle, message when examining something, dead corpse, fire) 
typedef struct {
	unsigned char opcode;	/* 0x2c */
	unsigned char id;	/* Index of item in array of room objects list */
	unsigned char type;
	unsigned char unknown0[3];
	short x,y,w,h;
	unsigned short unknown1[3];
} script_npitem_set_t;
The non-pickable object is added to the room objects list.
0x2d Obj_model_set 38 Special item? Typewriter? Event trigger 
typedef struct {
	unsigned char opcode;	/* 0x2d */
	unsigned char id;	/* Index of item in array of room objects list */
	unsigned short unknown[18];
} script_inst2d_set_t;
This object is added to the room objects list.
0x2e Work_set 3 
				/* component:index */
				/* 0x01:0x00: player entity */
				/* 0x03:NN: entity NN (enemy, etc) */
				/* 0x04:NN: room entity NN (ladder, door, etc) */
} script_setactiveobject_t;
This instruction select current object (player, entity, room object) on which further instructions will apply.
0x2f Speed_set 4 
typedef struct {
	unsigned char opcode; /* 0x2f */
	unsigned char component;	/* 0,1,2 number of word  */
	short value;	/* Value to set for n-th component */
} script_setregimm_t;
This instruction sets one of the words of an internal register (composed of 3 words).

0x30-0x3f

Byte Instruction Length Description
0x30 Add_speed 1 Sets internal register from an internal memory location.
0x31 Add_aspeed 1 Add 6 words together
0x32 Pos_set 8 Set 3 words
0x33 Dir_set 8 Set 3 words
0x34 Member_set 4 
typedef struct {
	short unknown0[2];	/* 0x00 */
	char unknown1[5];
	char dummy0;
	char unknown2[2];
	long dummy1;

	long unknown3;		/* 0x10 */
	long dummy2[3+4+2];

	long unknown4[3];	/* 0x38 */
	long dummy3[3+4+4+1];

	short unknown5[3];	/* 0x74 */
	long dummy4[23];

	char unknown6;		/* 0x106 */
	char dummy5[77];

	short unknown7;		/* 0x154 */
	char dummy6[108];

	short unknown8[3];	/* 0x1c2 */
	long dummy7;

	short unknown9;		/* 0x1cc */
	long dummy8;

	short unknown10[4];	/* 0x1d4 */
} script_inst34_var_t;
Set value in the structure of an entity (EM_SET).
0x35 Member_set2 3 
typedef struct {
	unsigned char opcode;	/* 0x35 */
	unsigned char id;	/* Value to change for current entity */
				/* 0x0b: X pos */
				/* 0x0c: Y pos */
				/* 0x0d: Z pos */
				/* 0x0e: X angle */
				/* 0x0f: Y angle */
				/* 0x10: Z angle */
	unsigned char varw;	/* Variable to use */
} script_em_set_var_varw_t;
Copy content varw variable value to a given value for current entity.
0x36 Se_on 12 
typedef struct {
	unsigned char opcode;	/* 0x36 */
	unsigned char unknown0;
	short unknown1[2];
	short unknown2[3];
} script_inst36_t;
0x37 Sca_id_set 4 Change camera
0x38 Flr_set 3 
typedef struct {
	unsigned char opcode;	/* 0x38 */
	unsigned char id;	/* Index in array of object at offset 11 of file */
	unsigned char flag;	/* Flag to clear or set bit 15 of last word of object at offset 11 */
} script_floor_set_t;
0x39 Dir_ck 8
0x3a Sce_espr_on 16 2D animation above background (fire)
0x3b Door_aot_se 32 
typedef struct {
	unsigned char opcode;	/* 0x3b */
	unsigned char id;	/* Index of item in array of room objects list */
	unsigned short unknown0[2];
	short x,y;	/* Location of door */
	short w,h;	/* Size of door */
	short next_x,next_y,next_z,next_dir;	/* Position and direction of player after door entered */
	unsigned char stage;	/* Stage,room,camera after door entered */
	unsigned char room;
	unsigned char camera;
	unsigned char unknown1;
	unsigned char door_type;
	unsigned char door_lock;
	unsigned char unknown2;
	unsigned char door_locked;
	unsigned char door_key;
	unsigned char unknown3;
} script_door_t;
The door is added to the room objects list.
0x3c Cut_auto 2 
typedef struct {
	unsigned char opcode; /* 0x3c */
	unsigned char screen; /* 0: item screen, 1: map screen */
} script_status_set_t;
Select which screen (inventory or map) to show when switching to status screen with instruction 0x42.
0x3d Member_copy 3 
typedef struct {
	unsigned char opcode;	/* 0x3d */
	unsigned char varw;	/* Variable to use */
	unsigned char id;	/* Value to read for current entity */
} script_em_get_var_varw_t;
Copy a given value for current entity to varw variable.
0x3e Member_cmp 6 
typedef struct {
	unsigned char opcode; /* 0x3e */
	unsigned char unknown0;
	unsigned char unknown1;
	unsigned char compare;	/* Compare function */
				/* 0: EQ */
				/* 1: GT */
				/* 2: GE */
				/* 3: LT */
				/* 4: LE */
				/* 5: NE */
				/* 6: ? */
	short value;	/* Value to compare against */
} script_cmpimm_t;
Compare immediate value against a memory location
0x3f Plc_motion 4 
typedef struct {
	unsigned char opcode; /* 0x3f */
	unsigned char unknown[3];
} script_inst3f_t;

0x40-0x4f

Byte Instruction Length Description
0x40 Plc_dest 8 
typedef struct {
	unsigned char opcode; /* 0x40 */
	unsigned char dummy;
	unsigned char unknown0[2];
	short unknown0[2];
} script_inst40_t;
Select animation pose and direction of current active entity.
0x41 Plc_neck 10 
typedef struct {
	unsigned char opcode; /* 0x41 */
	unsigned char unknown0;
	unsigned short unknown1[4];
} script_inst41_t;
0x42 Plc_ret 1 Switch to status screen (after having picked up an item, or used an item).
0x43 Plc_flg 4
0x44 Sce_em_set 22 
	unsigned char state;
	unsigned char unknown0;
	unsigned char unknown1;
	unsigned char sound_bank;

	unsigned char texture;
	unsigned char killed_id;/* entity index in internal bit array */
				/* seems to be unique for all entities of the game */
				/* to know which ones have been killed, and must */
				/* not be re-added to room when player come back */
	short x,y,z,dir;	/* position and direction of entity */

	unsigned short unknown2[2];
} script_em_set_t;
Entity (enemy, other character)
0x45 Col_chg_set 5
0x46 Aot_reset 10 
typedef struct {
	unsigned char opcode;	/* 0x46 */
	unsigned char id;	/* Index in list of room objects (doors, items, etc) */
	unsigned char unknown0[2];
	unsigned short unknown1[3];
} script_inst46_t;
Seems to define the action to do when the player triggers an event.
0x47 Aot_on 2 
typedef struct {
	unsigned char opcode;	/* 0x47 */
	unsigned char id;	/* Index in list of room objects (doors, items, etc) */
} script_inst47_t;
Activate object, present in the room objects list. For example, use a computer or open a desk.
0x48 Super_set 16
0x49 Super_reset 8
0x4a Plc_gun 2
0x4b Cut_replace 3 
typedef struct {
	unsigned char opcode;	/* 0x4b */
	unsigned char cam[2];
} script_camswitch_swap_t;
Browse the list of camera switches (offset 8 of file), swapping all values of camera 'from' and 'to' that matches cam[0] and cam[1].
0x4c Sce_espr_kill 5
0x4d ? 22
0x4e Item_aot_set 22 Pickable object? Typewriter? 
typedef struct {
	unsigned char opcode;	/* 0x4e */
	unsigned char id;	/* Index of item in array of room objects list */
	unsigned long unknown0;
	short x,y,w,h;
	unsigned short type;	/* 0x07: flower? typewrite ribbon? 0x14: ammo for gun */
	unsigned short amount;	/* For ammo: number of bullets/shells/etc */
				/* For a key: number of times it can be used before the 'Discard key?' message */		
	unsigned short array08_idx;	/* Bit number in array 0x08 (see end of section) */
	unsigned short unknown1;
} script_item_set_t;
The item is added to the room object list.
0x4f Sce_key_ck 4 
typedef struct {
	unsigned char opcode;	/* 0x4f */
	char unknown1;
	short unknown2;
} script_inst4f_t;

0x50-0x5f

Byte Instruction Length Description
0x50 Sce_trg_ck 4 
typedef struct {
	unsigned char opcode;	/* 0x50 */
	char unknown1;
	short unknown2;
} script_inst50_t;
0x51 Sce_bgm_control 6 
typedef struct {
	unsigned char opcode;	/* 0x51 */
	unsigned char unknown[5];
} script_inst51_t;
Seems related to music initialization
0x52 Sce_espr_control 6 
typedef struct {
	unsigned char opcode;	/* 0x52 */
	unsigned char unknown[5];
} script_inst52_t;
0x53 Sce_fade_set 6 
typedef struct {
	unsigned char opcode;	/* 0x53 */
	unsigned char unknown[5];
} script_inst53_t;
Seems related to fade in/out settings.
0x54 Sce_espr3d_on 22 
typedef struct {
	unsigned char opcode;	/* 0x54 */
	unsigned char dummy;
	short unknown[10];
} script_inst54_t;
0x55 Member_calc 6 
typedef struct {
	unsigned char opcode;	/* 0x55 */
	unsigned char dummy;
	short unknown[2];
} script_inst55_t;
0x56 Member_calc2 4 
typedef struct {
	unsigned char opcode;	/* 0x56 */
	unsigned char unknown[3];
} script_inst56_t;
0x57 Sce_bgmtbl_set 8 
typedef struct {
	unsigned char opcode;	/* 0x57 */
	unsigned char dummy;
	short unknown[3];
} script_inst57_t;
0x58 Plc_rot 4 
typedef struct {
	unsigned char opcode;	/* 0x58 */
	unsigned char unknown0;
	short unknown1;
} script_inst58_t;
0x59 Xa_on 4 
typedef struct {
	unsigned char opcode;	/* 0x59 */
	unsigned char channel;	/* channel on which to play sound ? */
	short id;	/* ID of sound to play, i.e. file PLn/VOICE/STAGEn/Vxxx.SAP, with id=xxx */
} script_sndplay_t;
Play sound (character voice for example).
0x5a Weapon_chg 2 
typedef struct {
	unsigned char opcode;	/* 0x5a */
	unsigned char item;	/* Item ID to check */
} script_inst5a_t;
Checks player inventory.
0x5b Plc_cnt 2 
typedef struct {
	unsigned char opcode;	/* 0x5b */
	unsigned char unknown;
} script_inst5b_t;
0x5c Sce_shake_on 3 
typedef struct {
	unsigned char opcode;	/* 0x5c */
	char unknown[2];	/* Values are sign-extended to LONG before being processed */
} script_inst5c_t;
0x5d Mizu_div_set 2 
typedef struct {
	unsigned char opcode;	/* 0x5d */
	unsigned char unknown;
} script_inst5d_t;
Seems related to 3D model creation
0x5e Keep_Item_ck 2 
typedef struct {
	unsigned char opcode;	/* 0x5e */
	unsigned char item;	/* Item ID to check */
} script_item_have_t;
Check whether player has item in its inventory or not.
0x5f Xa_vol 2 
typedef struct {
	unsigned char opcode;	/* 0x5f */
	unsigned char unknown;
} script_inst5f_t;
Seems related to volume or balance, for music or sound fx

0x60-0x6f

Byte Instruction Length Description
0x60 Kage_set 14 
typedef struct {
	unsigned char opcode;	/* 0x60 */
	unsigned char unknown0[5];
	short unknown1[4];
} script_inst60_t;
0x61 Cut_be_set 4 
typedef struct {
	unsigned char opcode;	/* 0x61 */
	unsigned char unknown[3];
} script_inst61_t;
Related to camera switches
0x62 Sce_Item_lost 2 
typedef struct {
	unsigned char opcode;	/* 0x62 */
	unsigned char item;	/* Item ID to remove */
} script_item_remove_t;
Remove item from player inventory, after usage.
0x63 Plc_gun_eff 1
0x64 Sce_espr_on2 16
0x65 Sce_espr_kill2 2 
typedef struct {
	unsigned char opcode;	/* 0x65 */
	unsigned char unknown;
} script_inst65_t;
0x66 Plc_stop 1
0x67 Aot_set_4p 28 Walls 
typedef struct {
	unsigned char opcode;	/* 0x67 */
	unsigned char id;	/* Index of item in array of room objects list */
	unsigned short unknown0[2];
	short xycoords[4*2];	/* X,Y coordinates of 4 points defining a zone the player can not exit */
	unsigned short unknown1[3];
} script_wall_set_t;
The wall is added to the room objects list.
0x68 Door_aot_set_4p 40 
typedef struct {
	unsigned char opcode;	/* 0x68 */
	unsigned char id;	/* Index of item in array of room objects list */
	unsigned short unknown[19];
} script_inst68_t;
This object is added to the room objects list.
0x69 Item_aot_set_4p 30 
typedef struct {
	unsigned char opcode;	/* 0x69 */
	unsigned char id;	/* Index of item in array of room objects list */
	unsigned short unknown[14];
} script_inst69_t;
This object is added to the room objects list.
0x6a Light_pos_set 6 
typedef struct {
	unsigned char opcode;	/* 0x6a */
	unsigned char dummy;
	unsigned char light;	/* Number of light to change */
	unsigned char param;	/* 11,12,13 for x,y,z */
	short value;	/* New value for parameter */
} script_light_set_pos_t;
Change one of the light position components, for current camera.
0x6b Light_kido_set 4 
typedef struct {
	unsigned char opcode;	/* 0x6b */
	unsigned char light;	/* Number of light */
	short brightness;	/* New value for brightness */
} script_light_set_bright_t;
Change brightness of one light, for current camera.
0x6c Rbj_reset 1 Related to offset 22 of RDT file
0x6d Sce_scr_move 4 
typedef struct {
	unsigned char opcode;	/* 0x6d */
	unsigned char dummy;
	short y;	/* New value for starting row */
} script_bg_set_pos_y_t;
Set first row of screen to draw background images (Used for scrolling in room2000).
0x6e Parts_set 6 
typedef struct {
	unsigned char opcode;	/* 0x6e */
	unsigned char dummy;
	unsigned char unknown[2];
	unsigned short value;
} script_inst6e_t;
Set value in some memory location.
0x6f Movie_on 2 
typedef struct {
	unsigned char opcode;	/* 0x6f */
	unsigned char id;	/* Movie to play */
} script_movie_play_t;
Play movie.

0x70-0x7f

Byte Instruction Length Description
0x70 Splc_ret 1
0x71 Splc_sce 1
0x72 Super_on 16
0x73 Mirror_set 8
0x74 Sce_fade_adjust 4
0x75 Sce_espr3d_on2 22
0x76 Sce_Item_get 3 
typedef struct {
	unsigned char opcode;	/* 0x76 */
	unsigned char id;	/* Number of gitemXX.adt file to load */
	unsigned char amount;	/* Amount */
} script_inst76_t;
Add item to inventory (like the guy giving the blue keycard at the start of RE2).
0x77 Sce_line_start 4
0x78 Sce_line_main 6
0x79 Sce_line_end 1
0x7a Sce_parts_bomb 16
0x7b Sce_parts_down 16
0x7c Light_color_set 6 
typedef struct {
	unsigned char opcode;	/* 0x7c */
	unsigned char light;	/* Number of color to set for current camera */
	unsigned char r,g,b;	/* R,G,B component of color */
	unsigned char dummy;
} script_light_set_color_t;
Set color of one light, for current camera
0x7d Light_pos_set2 6 
typedef struct {
	unsigned char opcode;	/* 0x7d */
	unsigned char camera;	/* Camera */
	unsigned char light;	/* Light */
	unsigned char param;	/* 11,12,13 for x,y,z */
	short value;	/* New value for parameter */
} script_light_cam_set_pos_t;
Change one of the light position components, for a given camera.
0x7e Light_kido_set2 6 
typedef struct {
	unsigned char opcode;	/* 0x7e */
	unsigned char dummy;
	unsigned char camera;	/* Camera */
	unsigned char light;	/* Light */
	short brightness;	/* New brightness */
} script_light_cam_set_bright_t;
Change light brightness, for a given camera.
0x7f Light_color_set2 6 
typedef struct {
	unsigned char opcode;	/* 0x7f */
	unsigned char camera;	/* Camera */
	unsigned char light;	/* Light */
	unsigned char r,g,b;	/* R,G,B component of color */
} script_light_cam_set_color_t;
Set light color, a given camera.

0x80-0x8e

Byte Instruction Length Description
0x80 Se_vol 2 Multiply some values
0x81 ? 3+? Perform a comparison
0x82 ? 3
0x83 ? 1
0x84 ? 2
0x85 ? 6 Related to offset 6 of RDT file
0x86 Poison_ck 1 Check player poisoned status.
0x87 Poison_clr 1 Clear player poisoned status (when using blue herb).
0x88 Sce_Item_ck_Lost 3 
typedef struct {
	unsigned char opcode;	/* 0x88 */
	unsigned char item;	/* Item ID to check */
	unsigned char unknown;
} script_item_have_and_remove_t;
Check if player has a given item, and remove it from inventory if this is the case (likely used for single usage items).
0x89 ? 1
0x8a Nop 6
0x8b Nop 6
0x8c Nop 8
0x8d ? 24 Related to room object list
0x8e ? 24 Related to enemies

Variables

Instructions 0x23 to 0x27 use 16 bits variables.

Number Description
0x10 Temporary value
0x1a Current camera angle

Arrays for bit operations

Array Number Bit Description
0   Game status
  0x19 Difficulty (0:Easy, 1:Normal, or vice versa).
1   ?
  0x00 Character (0:Leon, 1:Claire).
  0x01 Scenario (0:A, 1:B).
  0x06 Game type (0:Leon/Claire, 1:Hunk/Tofu, or vice versa).
  0x1b Letter box mode for cut scenes (0:disabled, 1:enabled).
2   Temporary status inside room?
  0x07 Seems to be used as mutex on script functions, to avoid them being called twice, till current is finished.
3   ?
4   Permanent room status
  0x05 room2010: Set if player saw the licker outside the window.
  0x06 room2000: This bit controls whether doing the scrolling when first entering this room.
  0x12 room10b0: Set if player put red jewel #1.
  0x13 room10b0: Set if player put red jewel #2.
  0x1a room1010: Set if player already visited this room.
  0x1b room1010: Set if Kendo has been attacked.
  0x3a room3090: Set if player pushed button to get ladder down.
  0x48 room2000: Player put medal in unicorn fountain.
  0x55 room2040: Set if player entered the room for first time (see player from outside).
  0x56 room2040: Set if player encountered licker for first time.
  0x5b room60c0: Set if player registered finger print.
  0x88 room7000: Set if player reenabled electricity for train gate.
  0x8c room7000: Set if player opened train gate.
  0x8e room60c0: Set if finger print verified in Scenario B.
  0x8f room60c0: Set if finger print verified in Scenario A.
  0x90 room7010: Set if player opened sockets stock.
  0x94 room1100: Set if player pushed button to bring down ladder to room2000.
  0x99 room2040: Set if cord on shutter is broken.
  0xaf room2070: Set if player used special key.
  0xfe Set for any room than needs some reinitialization?
5   ?
  0x02 room2040: Set if player examined corpse once.
  0x03 room1010: Set if player examined dead Kendo once.
  0x05 room1000: Related to lighting init.
  0x06 room1000: Related to fire animations init.
  0x07 room1000: Related to fire animations init.
  0x0e room1000: Set if player reached camera #5, triggers zombies change.
  0x12 room1030: Set if Brad must appear in this room.
  0x20-0x24 Set if entity (player, enemy, etc) is in targeted pose (instruction 0x40).
6   Entities killed status Each bit is associated to a different enemy throughout the whole game, to check whether or not an enemy is definitely dead and should not respawn, when player reenter a room.
7   ?
8   Item grabbed status Each bit is associated to an item (instruction 0x4e) and is set whenever the player grabs this item.
0x0b   Player input
  0x1f Player answered a question; 0:Yes, 1:No.
0x1d   Game status, kept through several replays.
  0x02 room60c0: Set if player unlocked door in Scenario A.
  0x09 room2040: Set if player used cord on shutter.
  0x0a room20f0: Set if player used cord on shutter.
  0x11 room1030: Set if player encounters Brad (for next game ?).

Offset 17, execution script for room

This script is run regularly to update stuff in current room. It follows same structure as the one at offset 16.

Offset 18

This location contains the list of animations used for a given room. For example, the fire animation when you start the game.

It starts with a 8-byte header. If the value is not 0xff, it means there is an animation. Counting these non-0xff bytes will tell how many block description there is following this header.

You should also have same number of TIM images at offset 20 in the file. It means up to 8 animations can be stored in a RDT file, and you'll find up to 8 TIM images respectively. 

typedef struct {
  /* A non 0xff value means there is an animation */
  char anim_id[8]; 
} rdt_anim_list_t;

Offset18, animations

Each animation starts with this header: 

typedef struct {
  unsigned short num_frames; /* Number of animation frames */
  unsigned short num_sprites; /* Number of sprites for animation */
  unsigned char height; /* Height of animation */
  unsigned char width;  /* Width of animation */
  unsigned short unknown;
} rdt_anim_header_t;

Offset18, animation steps

Following this header there is an array of 'num_frames' objects. 

typedef struct {
  char num_sprite; /* Number of sprite to use for this animation frame */
  char unknown0[7];
} rdt_anim_steps_t;

Offset18, animation sprites

And following this one is an array of 'num_sprites' sprites. 

typedef struct {
  unsigned char x,y;
  char offset_x,offset_y;
} rdt_anim_sprites_t;

x and y are top-left position of sprite in TIM image. Offset x,y are signed values to the center of the sprite, to offset the part of image correctly in the animation buffer.

Offset18, unknown block

Now we have a header for the following data, which seems to hold some relative offsets: 

typedef struct {
  unsigned short offsets[8];
} rdt_anim_unknown_t;

For each non zero offset, there is a data block of 0x38 bytes following. The offset to data block 'x' is given as '8+((offsets[x]-4)*4)'. 

unsigned char unknown[0x38];

Finally, there is the byte-length of the total block. 

unsigned long block_length;

Now you are ready to process next block;

Offset 20

Here lies a list of TIM image files that contains images to be used for animations. Each TIM image holds all image steps of a given animation.

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