Reference · Engine

In-engine cinematics

partialfrom#7#14#15#22#23

The story scenes are rendered by the engine from a database's models and rooms, driven frame by frame by a stream of small data sectors read from /DATA/CINEMAT with the XA dialogue and music interleaved.

play_cine (0x8007424c, cinemat.c)

play_cine(n) takes n < 93 ("Invalid cine number %d") from a table at 0x800b8bd0, 16 bytes an entry (byte 7 flags: 0x40, 0x20, 0x08, 0x01 seen tested; byte 6 a count of timed calls with a pointer at +8; byte 12 a post-scene flag). It starts the stream (0x80073810), then each frame: waits for the next data sector (0x8007412c), updates the camera (0x80088c80, 0x80088e0c), renders the scene (render, 0x80030b80), runs the entry's timed calls whose frame window contains the counter, and flips. It ends when the stream's frame counter (0x800c4c34) reaches the header's frame count, or on an end-marker sector.

The opening (Opening Cine Init, 0x8008f078) sets up database 22 (its textures, rooms, collision, models, hierarchy and loops) and the menu's eye and mouth TIMs before it.

The stream (0x80019da4)

Started with CdControlB(Setmode 0xc8), CdControlB(ReadS, the table's position), then Setmode 0xe9 (double speed, whole sector, XA filter, XA-ADPCM) and Setfilter(1, 1). The ready callback 0x80019c88 copies each data sector (4 words of header and subheader, then 511) into one of eight 2060-byte buffers at 0x800c7510 and points 0x800c3ee0 at its data (+12, or +16 when the table entry names a channel byte to check).

Sector contents

Little-endian.

first sector (header)
  u32  magic          0xf00dbabe (or 0xbabed00d)
  u16  version        must equal 0x800c43cc (OPEN.BIN: 3)
  u16  0xdead
  u16  frames         OPEN.BIN: 1412
  u16  setup_size     OPEN.BIN: 1380
  u8   setup[setup_size]   copied to a fresh block (0x800c43d8)
each later data sector: one frame
  u16  frame          from 1
  u16  unknown_02
  s32  camera position[3]
  u32  a              bits 0-12 q0, 13-25 q1 (signed), 26-31 actors
  u32  b              bits 0-12 q2, 13-25 q3 (signed), 26-31 poses
  actor[actors]       24 bytes (0x80073c34)
    u32  bits 0-12 q0, 13-25 q1, 26-29 mouth, 30-31 eyes
    u32  bits 0-12 q2, 13-25 q3
    s32  position[3]
    s16  id, u16 unknown_16
  pose[poses]         16 bytes and 8 a key (0x80073f08)
    s32  position[3]
    u32  bits 0-15 id, 16-23 keys, 24-27 mouth, 28-29 eyes
    key[keys]
      u32  bits 0-12 q0, 13-25 q1, 26-31 channel
      u32  bits 0-12 q2, 13-25 q3
  0xdddddddd          as the first word: the stream's end

Quaternions are (x, y, z, w) = (q0, q1, q2, q3), at any scale. Ids are the object registry's, from the database's LP file (lp).

Timing and sound

The audio sectors are four in five of the stream, yet one stereo 37.8 kHz channel at double speed needs one in eight. The encoder repeats each audio sector to fill the bandwidth (535 of the first 634 neighbours are byte for byte the same). The CD-ROM controller's decoder takes a sector only when its output has nearly drained and drops the rest (no flow control; DuckStation models it so: more than 10 frames queued, the sector is skipped and leaves the ADPCM history alone). The 5643 audio sectors of the opening come out as 882 played, 47.1 s, matching the 1412 frames at 30 a second. Decoding every sector gives 300 s with each piece repeated about six times.

The stream's data sectors arrive every 5 sectors at double speed (OPEN.BIN: frame 1 at sector 2, frame 1412 at sector 7056), so 30 frames a second; the XA between them is filtered to file 1, channel 1 (cine 0 has no channel byte in the table at 0x800b4290; one with a channel starts 2 sectors a channel in and its data sectors are read from +16). The CD volume is the cine table's byte +0x0d (100 for the opening).

Each frame play_cine samples the pads after drawing (0x8001d3e8 calls 0x8001acc0), and stops when the first port's Triangle history reads "pressed" (0x800cda4c & 3 == 1), or when the counter reaches the frame count. With the entry's flag 0x01 clear it fades out over the last 13 frames (25 a frame into 0x800c3f2c); the opening has it set.

The opening's one timed call (entry 0x800b8bc8: frames 1184 to 1413, 0x8008ea70, called with the counter) is the ending: the milk at the lens, then the title card. Opening Cine Init (0x8008f078) makes two objects at the origin, unturned: the milk (model 948, D_800c4da8) and the sign (model 1038, D_800c4dac), and two unturned cameras (0x8008e8c0(1), 0x8008e99c(1)): A at (2250, -2450, -5000) (0x800b8ba8), B at (0, 30, -17048) (0x800b8bb8). Each call:

• While the milk flies (+0xd0 = 1), k = min(counter, 1213) - 1183: A at (2250 - 75k, -2450 + 81k, -5000 + 160k), the milk's +0x28 = 273k. The milk is drawn from A (0x80031b84, layer 1): it shows small at the bottle's tip and fills the screen by frame 1213.
• While A's x is above 0, nothing more.
• Then the flight ends (+0xd0 = 0). While B's z is below -500 it moves 600 a frame; reaching -500 it stops there, A's z becomes -300 and B gets field of view 512 (0x8001dfb8: H 386, set for all that follows). The sign is drawn from B (layer 2).
• From the next call: "Search For Reptar" (font 1, y 60) and "Loading" (font 0, y 85), both (100, 200, 0) with shadows (1, 1, 1) 2 down and right, centred (0x8002e144, 0x8002e67c), and the trademark (0x8003f0f0).

The squirt's sound is in the soundtrack (its loudest moment at 40.0-40.5 s, frame 1213 at 40.4 s); the stream carries no sound cues (frame +0x02 is 1380 throughout, the actors' +0x16 is 0).

The port: media::ending, checked against the oracle's pictures at vblanks 9220-9400 (counter 1218 at 9220, 1246 at 9250).

Applying a frame

• The camera (0x80073b08): position to 0x800e5648, the quaternion through 0x80020580 (the transpose of the parts' 0x8001fc48) to the camera matrix at 0x800e5428, and 0x8001e0f4 makes the view matrix (0x800e5448) from it by scaling its x row by (s16 0x800c4a14) / 320 and its y row by (s16 0x800c4a16) / 240: 512 and 240 here, so x by 1.6. A point p is seen at view (p - camera) (0x8001eb4c), projected with H 178 and no offset onto the 512 x 240 screen.
• An actor (0x80073c34) is a single-model object: its rotation goes through 0x8001f9fc to object +0x04, its position to object +0x18. Ids 510 and 511 are special: the actor is moved 0x2000 down with +0x24 set to 1024, and object 602 (601 for 511) takes the record's rotation and position instead, its +0x24 growing by 50 a frame to 1024 once 0x800c43d0 passes 50 (a swap, or a fade in; not yet seen).
• A pose (0x80073f08) is a hierarchy object: position to object +0x18, angles at +0x24 cleared, and each key's quaternion to the part its channel maps to (hierarchy +0x14 + channel, 0xff for none). The object is the registry's by the id (0x800461f4), a character (+0xa6 1) in a room or not; it is put in the room at its new place (0x8004a218: out of the old room's characters' list +0x4c, into the new one's), and the floor under the place is looked up (0x8002b240 into +0x13c, +0x148), but its height is not settled. So level 13's Angelica, placed off the map, is left at cine 6's (23346, -5625, -4942), and level 7's babies, placed in no room, are in room 12 after cine 79.

Faces

Mouths and eyes are blocks of texture that the cinematic overwrites in VRAM (LoadImage after DrawSync) with frames from face banks:

• The banks are files 531-550, each loaded with a 64-byte header skipped (0x80074b9c), one per bit of the face mask at 0x800c4c70. A level's setup (0x80017c0c) takes the mask from 0x800b91a0 + 4 db; the opening's (0x8008f078) from db 22's, 0xd515.
• The mouth setter 0x80074ec0(frame, id) and the eye setter 0x80075304(id, frame) map an id to its bank and rect. A frame is w x h words into the bank. A mouth frame past the count wraps back once (10; 12 for id 88; 13 for id 112).

Bit to file: 0 535, 1 531, 2 536, 3 532, 4 537, 5 545, 6 538, 7 546, 8 539, 9 540, 10 541, 11 542, 12 543, 13 544, 14 533, 15 534, 16 547, 17 548, 18 549, 19 550.

Ids 88 and 112 are not faces. They are the opening's milk effects, whose texture the stream animates through the mouth field: 88 is the spray from Tommy's bottle (records 599-608), and 112 is the splash over the lens (from record 830).

How the records drive them:

• An actor (0x80073c34) first resets mouth and eyes to frame 0. Then a nonzero mouth field sets that frame, and a nonzero eyes field sets frame eyes - 1.
• A pose (0x80073f08) first blinks (0x80075698), then takes the same fields without the reset.
• The blink runs per object: state +0xa5, count +0xa7, and a rand of its own at 0x800c4c48 (x * 214013 + 2531011) that play_cine seeds with the cinematic's number. When open, the blink starts with a 1 in 32 chance ((x >> 16) & 31 == 0). It then shows eye frame 1 for three records and frame 2 for two.

The backdrop is a fill of (217, 175, 141): play_cine's setup (0x8007475c) calls set_backdrop(view, r, g, b) (0x8001d218, view 3 at 0x800cdf18) with it, which turns on the view's DRAWENV isbg.

Measured

rugrats-viewer 22 --cine 199 (rooms, LP props, stream actors and poses, this camera) against the oracle's picture when the counter at 0x800c4c34 reads 200 (oracle frame 2039; the picture shows the frame before): the camera position equals the oracle's, every pose's keys equal the oracle's part quaternions, and rooms, props and characters line up. The original's wall shading (depth cue and lighting) is not drawn yet.

Faces (cine_faces against the oracle's VRAM, cine_blink against its blink rand):

• Every face rect at records 300, 604 and 840 equals the oracle's, except for blink timing.
• The oracle drops records when a frame runs long, 104 of the first 840. Each dropped record is a pose pass it never makes, so its blink rand falls behind the port's by those calls. Up to record 88, where nothing has dropped yet, the two take the same rand step for step.

Unknown

• unknown_02 (1380, the setup's size, in every OPEN.BIN frame), the setup block, the rest of the 16-byte table entries.
• Whether the real drive and GPU drop records as the oracle does, which sets when the characters blink.
• Whether Triangle really skips: the oracle has no input during the cinematic (see input).