Final Fantasy VI battle graphics and sound (everything8215's disassembly)

On a town or dungeon map, a battle starts with the battle sound effect, number $C1, and 32 frames of mosaic over the background layers before the field hands over to the battle program. Each frame the routine writes the mosaic size into all eight entries of the field's mosaic HDMA table, which feeds the mosaic register: for the first 15 frames the size counts 1 to 7 and then 0 to 7, for the next 16 it counts 0 to 15, and on the 32nd it is 0 again. A size of n draws blocks n + 1 pixels square, so the screen breaks up twice into blocks up to 8 pixels and then once into blocks up to 16. Two flags can turn the sound or the blur off: a battle started by event command $4E turns both on, the Colosseum turns both off, and a monster-in-a-box battle takes them from the top two bits of its event command's background byte. ff6-av/field-battle-mosaic

About: Final Fantasy VI HDMA

{
 "frames": 32,
 "sfx": 193,
 "sizes": [
  1,
  2,
  3,
  4,
  5,
  6,
  7,
  0,
  1,
  2,
  3,
  4,
  5,
  6,
  7,
  0,
  1,
  2,
  3,
  4,
  5,
  6,
  7,
  8,
  9,
  10,
  11,
  12,
  13,
  14,
  15,
  0
 ]
}

The mosaic register's high nibble is the size and its low nibble picks the layers; $0F sets BG1 to BG4. The size sequence is computed: the counter is cleared, then incremented by the NMI before the first read, so the first frame reads 1; the frame that reads 32 still writes its size (32 AND 15 = 0) before the loop ends.

Cited by: Battle transition, Mosaic

On the world map, a random battle starts with the battle sound effect and a 34-frame Mode 7 zoom. Each frame takes a pair from a table, the high byte of the zoom level the world map's Mode 7 code reads and the screen brightness. The zoom byte falls from $85 to $18 over the first 8 frames, rises back to $6D by the 16th, eases to $58 by the 24th, and over the last 10 falls to 0 while the brightness steps down from full (15) through 13, 12, 11, 9, 8, 7, 5, 4, 3 to 1. The routine also leaves only BG1 and BG2 on the main screen and clears the sub screen. ff6-av/world-battle-zoom

About: Final Fantasy VI Mode 7

{
 "frames": 34,
 "zoom": [
  133,
  112,
  92,
  58,
  45,
  35,
  25,
  24,
  27,
  41,
  50,
  61,
  83,
  92,
  100,
  109,
  109,
  108,
  105,
  104,
  101,
  95,
  92,
  88,
  78,
  73,
  68,
  56,
  49,
  43,
  29,
  22,
  15,
  0
 ],
 "brightness": [
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  15,
  13,
  12,
  11,
  9,
  8,
  7,
  5,
  4,
  3,
  1
 ]
}

Each table word is little-endian, so its low byte is the zoom and its high byte the brightness. Which way a larger zoom number moves the view is the world map's Mode 7 projection's business, which this claim doesn't read: it gives the numbers, not the direction. TM = $03 is BG1 and BG2.

Cited by: Battle transition

Two more transitions start battles from the world map's other modes, the Magitek train ride (as the disassembly names it) and the world map with a vehicle: each pass of the mode's main loop checks a battle-enabled bit and, when it is set, runs the mode's transition. On the train the routine plays the sound effect the field's battle mosaic plays ($C1) and writes 41 bytes straight to the mosaic register, one a frame: block size 1 up to 13 pixels, back down to 1, and up to 16, all four background layers on. With a vehicle, the effect plays the battle sound and lowers the screen brightness by one a frame for 40 frames, stopping at 0. ff6-av/other-battle-transitions

{
 "trainBytes": 41,
 "trainSizes": [
  0,
  1,
  2,
  3,
  4,
  5,
  6,
  7,
  8,
  9,
  10,
  11,
  12,
  12,
  11,
  10,
  9,
  8,
  7,
  6,
  5,
  4,
  3,
  2,
  1,
  0,
  1,
  2,
  3,
  4,
  5,
  6,
  7,
  8,
  9,
  10,
  11,
  12,
  13,
  14,
  15
 ],
 "vehicleFrames": 40
}

The sizes are each byte's high nibble; block size in pixels is the size plus 1. The train's loop waits on $fa, which the train ride's NMI increments each time it runs (its comment calls it a 4-frame counter, but the increment is unconditional), and the vehicle effect's loop on $24, which the vehicle NMI increments as its vblank flag; the NMI runs once a frame.

The battle screen opens from a line across the middle of the battlefield. It starts black: every line of an HDMA table that feeds the color math registers subtracts full white from BG1 to BG3 and the sprites. Each frame the clear band grows by two lines up and two down from line 76, the battlefield's middle, and beyond each edge the subtraction rises by one step (of 31) every two lines, so the band's edges are soft gradients 62 lines deep. After 38 frames all 152 battlefield lines are clear and the channel goes back to its window table. Meanwhile the screen brightness rises by one each frame, from 1 to full (15) in 15 frames. ff6-av/battle-fade-in

About: Final Fantasy VI HDMA

Value: frames 38 · middle line 76 · battlefield lines 152 · lines per step 2 · brightness frames 15

Each table entry is two bytes, the color math control ($2131) and the fixed color ($2132); $97 subtracts from BG1 to BG3 and sprites, and the fixed color byte's top three bits pick red, green and blue with its low five the intensity, so $E0 is 0 and $FF is 31. The writes land on the odd bytes, the fixed color. Lines 152 on are the menu, whose gradient the same initialisation copies in (init.asm#L700-L705).

Cited by: Color math

A battle's song comes from its battle properties: bits 3 to 5 of the fourth byte index an 8-entry battle song table (in the disassembly's names the battle theme, Decisive Battle, Fierce Battle, Returners, Save Them, and Dancing Mad parts 1 to 3, then two entries that mean keep the song playing); bit 7 set leaves the music alone. A character-AI scene's own song, when it names one, takes the table's place, and a random battle started while an event flag is set keeps the map's music. The same byte's bit 2 turns off preemptive strikes and the four messages that announce a battle's start: back attack, pincer attack, side attack and preemptive strike. When the battle ends, the end command fades the music out unless the battle kept the music playing (bit 7, or the map's song) and no victory fanfare played; the fanfare, which plays only when the map's song wasn't kept, always brings the fade. ff6-av/battle-music

About: Final Fantasy VI Music driver

Value: songs BATTLE_THEME, DECISIVE_BATTLE, FIERCE_BATTLE, RETURNERS, SAVE_THEM, DANCING_MAD_1_2_3, NONE, NONE

Which battles use each index is counted in [ff6-tables/tracks](#ff6-tables/tracks). SONG::NONE is $FF, which the code reads as keep the song. Command $81 to the sound driver is the fade (sound_main.asm); this claim doesn't read its rate.

A battle's background is picked before the battle starts. On a town or dungeon map it is the map's own battle background. On the world map the terrain under the party gives an index 0 to 7, and a table of eight backgrounds for each world turns it into one (field, forest, desert, a second forest, Zozo's interior, the World of Ruin's field, the Veldt, and clouds in the World of Balance; the World of Ruin swaps in its own desert and its field twice). The Colosseum sets its own, and a monster-in-a-box battle takes its event command's background unless that is $3F, which falls back to the map's. A character-AI scene can name a special one. ff6-av/battle-background

The table's names are the disassembly's constants; "the World of Ruin's field" is FIELD_WOR, which the World of Balance's sixth slot also uses. The same index picks the world map's battle rate and group (BattleBGRateTbl, BattleBGGroupTbl), as [ff6/encounter-rate](#ff6/encounter-rate) reads.

A damage or healing number is drawn as two 16-pixel-wide sprites over the target, built each time from digit tiles: the value's low 14 bits are turned into decimal digits by counting off thousands, hundreds and tens, leading zeros are dropped, and each digit is 8 pixels wide, so the number is shifted left by half its width (4, 8, 12 or 16 pixels) to center it. Damage uses sprite palette 4, which the source calls white, and healing palette 5, green; a miss draws a "miss" graphic instead, shifted by 8. Four number slots serve single targets, and a new number for a target that already shows one waits 8 frames first; a spell over several targets draws its numbers with a command that runs over 10 entries, one for each character and monster. The conversion has no ten-thousands place: a value over 9999 would count 10 to 16 into the thousands digit, which this claim doesn't follow to the screen, nor whether the battle program keeps damage below it. A number is hidden on any frame its sprite is on line 151 or lower, where the menu begins. ff6-av/damage-numerals

Value: slots 4 · multi slots 10 · digit width 8 · max digits 4 · value bits 14 · damage palette 4 · heal palette 5 · miss offset 8 · same target wait 8 · hide from line 151

The source's comment on the line check reads "hide sprite if y position < $97", but the code keeps the sprite when the line is below $97 and moves it off screen (line $E0) otherwise. The width offsets are half of 8 pixels times the digit count. Healing is the green flag, bit 15 of the value word; the battle program sets it. The several-target command is graphics command $03, whose loop counts 10 entries with $10 and fills w7e7b3f one per character or monster; it converts with the same routine.

A damage or healing number lives 64 frames and moves by a 65-byte table of heights above its start: it rises to 16 pixels by its 10th frame, holds there to the 14th, falls back to its start on the 24th, bounces once to 8 pixels around frames 31 and 32, lands on the 39th, and sits still for the last 25 frames. Numbers over a single target and over several targets read the same table. ff6-av/damage-number-bounce

{
 "frames": 64,
 "heights": [
  3,
  6,
  8,
  10,
  11,
  13,
  14,
  15,
  15,
  16,
  16,
  16,
  16,
  16,
  15,
  15,
  14,
  13,
  11,
  10,
  8,
  6,
  3,
  0,
  3,
  4,
  5,
  6,
  7,
  7,
  8,
  8,
  7,
  7,
  6,
  5,
  4,
  3,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0,
  0
 ],
 "peak": 16,
 "bounce": 8
}

Frame numbers count from 1 for the table's first entry. The table's 65th byte is never read, since the counter stops at 64. Heights are subtracted from the sprite's line, so they lift the number.

When ordinary monsters die, each dying monster's sprites switch to sprite palette 3, which is loaded with a 16-color death palette: after the transparent color and a near-black, 14 shades of magenta from full red and blue (31, 0, 31) down to (3, 0, 3), so the monster turns into a magenta figure that keeps its own shading. The monster-death sound, number $2D, plays, and for 32 frames every color of that palette loses one step of red, green and blue (of 31), stopping at black, so the figure is black from the 31st frame. Color math is set for the time to add the sub screen, which holds only sprites, to BG2. Then the dead monsters leave the shown set and color math goes back to off. ff6-av/monster-death

About: Final Fantasy VI Palette swap

Value: frames 32 · sfx 45 · palette 3 · colors 12684, 1025, 31775, 29725, 25625, 23575, 21525, 19475, 17425, 15375, 13325, 11275, 9225, 7175, 5125, 3075 · cgwsel 2 · cgadsub 2 · sub screen 16

The palette words decode to red = blue = 31, 29, 25, 23, 21, 19, 17, 15, 13, 11, 9, 7, 5, 3 with no green: there is no 27. In flashback mode (wEnableFlashback) the palette is first filtered (FilterColors). How the add to BG2 combines with the dying monster on screen depends on the main screen's layers, which this pass didn't read; see the gap below.

A boss dies with a script of its own, about 490 frames (8 seconds) long, which the boss's AI script asks for (43 AI scripts do, among them those the disassembly names Vargas, Dadaluma, Ghosttrain, Atmaweapon and eight dragons). The background flashes white with a thunder sound and fades back over 8 frames, then holds 65; a second thunder flash whitens the background and the boss together, the boss fading back over 32 frames with color math adding the sprites to BG2, then a 32-frame hold. With a second sound the boss shakes for 32 frames, a pixel aside and back on alternate frames. Then at two frames a step it drains its color: blue goes in 32 steps over 127 frames (the first step still at one frame) while green loses half; green finishes and red loses half over the next 128 frames with the shake at 2 pixels; red finishes over 64 frames at 3 pixels. Then the monsters are hidden and the sound stops. ff6-av/boss-death

{
 "frames": 490,
 "aiScripts": 43,
 "phases": [
  {
   "what": "first flash",
   "frames": 73
  },
  {
   "what": "second flash",
   "frames": 64
  },
  {
   "what": "shake",
   "frames": 32
  },
  {
   "what": "blue",
   "frames": 127
  },
  {
   "what": "green",
   "frames": 128
  },
  {
   "what": "red",
   "frames": 64
  },
  {
   "what": "hide",
   "frames": 2
  }
 ]
}

The count of 43 is the AI scripts in battle/ai_script.asm with a boss_death line (40) or the line kill_monsters SELF, BOSS_DEATH (3), computed; a script can hold several. The dragons among them are the disassembly's White, Ice, Storm, Dirt, Gold, Skull, Blue and Red. anim_speed 3 assembles to the byte 2, and the interpreter's frame counter makes that a step every 2 frames (anim_cmd.asm#L2532-L2535). Command $84 sets only the rate, and the counter was reloaded with the old rate of 1 before the step that holds it ran, so that step lasts one frame and the 2-frame steps start with the next. The phases' frames are computed from the loop counts: 8 + 65, 32 + 32, 16 × 2, then 16 × 4 × 2 − 1, 16 × 4 × 2, 8 × 4 × 2, and the last step at two frames. Each palette step subtracts 1 of 31 from the monster sprite palettes 0 to 2, so 32 steps empty a component. The sounds are SEALED_GATE_THUNDER and BOSS_DEATH_B in the disassembly's names.

Every spell, attack and effect animation is a set of scripts, one per layer it draws on (sprites, BG1, BG3), named with its graphics, palettes, sound effect and an init function in the attack's animation properties. A script opens with two bytes, its speed (a step every 1 to 16 frames) and how it lines up on its target, then runs as a byte stream: a byte below $80 shows that frame of the animation and ends the step, $FF ends the script, and $80 to $FE are commands, $80 taking a second byte that picks one of a second set. Commands run at once, as many as come before the next frame byte, so palette changes, moves and register writes take no time of their own. Up to 85 threads run side by side, each counting down its own speed, and the effect lasts until none is left. ff6-av/anim-script-format

Value: threads 85 · speeds 1, 16 · frame bytes 0, 127 · end 255 · extended 128

The BG1 and BG3 threads take the same countdown before their own update routines; each layer has its own blank frame byte ($1F for sprites, $0F for BG1, $09 for BG3, in the macro file). A step ends when a frame byte is shown, so a script's length in frames is its frame bytes times its speed.

The animation scripts' commands, as the disassembly lists them: 127 one-byte commands, $80 to $FE, and 141 more behind $80, each with the macro the disassembly's scripts write it as and what its handler's header comment says it does, the rows compiled from those headers (52 say nothing). The two jump tables are built by a macro from the handlers' labels, so the labels are the list. Moving threads along lines, vectors, circles and arcs; loops and calls; palette adds, subtracts and cycles per layer; the scroll waves; color math, the main screen's layers, mosaic and the screen mode; Mode 7 moves, zooms, flips and rotation; window shapes; sound effects; and one-off commands for single spells and bosses. ff6-av/anim-commands

The descriptions are the disassembly's own and unchecked line by line, except the commands the other ff6-av claims quote. Command $C7 runs a separate set of battle event animation commands (event_anim.asm), not listed. A command with no macro is one the disassembly's scripts don't write by name. The scratch script is a framework candidate (reported). The $80 row's text and the split of the header for $8D and $8F are ours.

Five attack animations switch the battle to Mode 7 for part of their run, drawing BG1 as a rotating and scaling plane: Atom Edge and True Edge (one script; Atom Edge's init loads Odin's graphics), Purifier, H-Bomb, Overcast and S. Cross. The battle's shared Mode 7 init, which six attack init functions call (Atom Edge's among them), takes BG1 off the main screen and sets the matrix to 1.0 (A = D = $0100); script commands then change the zoom and position by signed steps, flip the plane, and write the screen mode. In Atom Edge the plane zooms by −8/256 a frame in both axes for 32 frames, down to 0 from 1.0, before the screen goes back to Mode 1. Overcast spins it: each frame the matrix is a rotation by −2 × the value the source comments as the frame counter whose size starts at 255 and drops by 2, for 127 frames. ff6-av/mode-7-effects

About: Final Fantasy VI Mode 7

Value: scripts 5 · unit 256 · atom edge zoom step -8 · atom edge frames 32 · overcast frames 127 · overcast radius step -2

The five, by their script headers: $011F Atom Edge, True Edge; $021A Purifier; $021E H-Bomb; $01B7 Overcast; $01AD S. Cross. The matrix's size and the plane's on-screen size go opposite ways (a smaller matrix samples less of the map per pixel), so Atom Edge's falling zoom value enlarges the plane, and a value of 0 would stretch one texel over the screen; Overcast's shrinking size also enlarges it as it turns. Sine is read through CalcSine16 with the size as amplitude; this claim doesn't read its scaling.

73 of the 565 attack animation scripts set color math with command $D4, more than cycle a palette (64) or set a scroll wave (47), counting as one script everything from a script's header in the disassembly to the next header, so a subroutine set after a script counts with it. The command writes the color math control for every line of an HDMA table and the sub screen's layers. One setting adds the sub screen, holding sprites, to a background, as the summons do while the party is hidden; others add a fixed color, which the disassembly's blue and rainbow gradients change from line to line. In Atom Edge the battle background fades out over 32 frames, a step of white subtracted each frame, while a blue gradient is added to it and the backdrop. ff6-av/color-math-effects

About: Final Fantasy VI HDMA

Value: scripts 73 · of 565 · gradient scripts 14

The table SetColorMathHDMA fills is channel 4's, which writes $212F-$2132 per line (interrupt_2.asm#L44-L47). The esper hide subroutine flickers the party, hiding and showing them on alternate frames, while their palettes darken by 32 steps of white subtracted; 9 scripts call it, Inferno among them.

Cited by: Color math

Backgrounds ripple through the battle's scroll HDMA: command $AC sets a layer's wave, its amplitude (one of eight sine tables built when the battle starts) and its speed, for the horizontal or vertical scroll of BG1, BG2 or BG3, and each $AE copies 32 words of that sine table, from the wave's phase on, into the layer's scroll HDMA table and advances the phase by the speed. 47 of the 565 attack scripts set a wave. Ifrit's Inferno runs one horizontal wave at the script's amplitude setting 4 and one vertical at 3 on the battle background through the whole summon while the background loses cyan, then over 16 frames at the end sets both to 3, 1 and 0. The copy picks the sine table from bits 1 to 3 of the setting only, so 4 picks the third of the eight tables, 3 the second, and 1 and 0 both the first. ff6-av/scroll-wave-effects

About: Final Fantasy VI HDMA

{
 "scripts": 47,
 "of": 565,
 "words": 32,
 "sineTables": 8,
 "infernoAmplitudes": {
  "horizontal": 4,
  "vertical": 3
 }
}

The source notes that only three of the amplitude's bits matter, picking one of the eight sine tables (_c1ef24) that battle init fills (btlgfx/init.asm, "init sine wave tables"). Inferno's closing steps are two 8-frame waits (_d05677) between the amplitude changes. How many lines each scroll table entry covers is the scroll HDMA tables' business (interrupt_2.asm), not read here.

Spell effects animate by palette cycling: commands $A3 and $A4 rotate a run of up to 15 colors in one battle palette one place right or left, once every n calls, where n is the command's speed. 64 of the 565 attack scripts cycle a palette. In Ifrit's Inferno the BG1 flames rotate colors 1 to 7 of the BG1 animation palette one place right every 2 frames for 66 frames, then every frame for 33 as the flames rise. ff6-av/palette-cycle-effects

About: Final Fantasy VI Palette cycling

{
 "scripts": 64,
 "of": 565,
 "infernoColors": [
  1,
  7
 ],
 "infernoPhases": [
  {
   "framesPerShift": 2,
   "frames": 66
  },
  {
   "framesPerShift": 1,
   "frames": 33
  }
 ]
}

$A4 is the same leftward. BG1_ANIM is battle palette 3 in the macro file's numbering (anim_script.mac#L1082). The run's length is the low four bits of the command's first byte, which the macro packs as range_end - range_begin + 1 under range_begin << 4, so 15 is the most.

When a battle is won, the victory command closes the battle menus and, unless the battle turns the fanfare off, queues battle event 1 and plays song $2F, the Victory Fanfare, at full volume, skipping the song when the map's music carries through the battle. Battle event 1 gives every character the same animation: a spin through four jump frames at one frame every 4 video frames, so 16 frames, and then the jumping-forward action. Dead and petrified characters get an empty script and stay as they are. ff6-av/victory-fanfare

About: Final Fantasy VI Music driver

Value: song 47 · spin frames 16 · frames per step 4

attacker_frame takes two frames, which the disassembly's names suggest are for the two facings. After the spin, anim_speed 2 writes the byte 1, a step every frame, before the pose. "Victory Fanfare" is the disassembly's song name; the track listing is [ff6-tables/tracks](#ff6-tables/tracks).

After the fanfare the battle program shows the results as battle messages, in this order: a Colosseum win shows only its prize item. Otherwise come the experience each living character gets (the defeated monsters' total, none on the Veldt, divided among the living, counted twice for one wearing the relic that doubles experience, the Exp. Egg in the source's comment); the magic points for espers, behind a check on Terra's Morph; then, character by character, one level-up message however many levels are gained, followed by each spell learned; then the Lores, a Dance Mog learns from the battle's background, a cursed shield's lifting, each item dropped (with a count when more than one), and the gil, doubled by the relic that doubles it, the cat hood in the source's comment. Sword techniques and Blitzes learned at a level come with the level up. ff6-av/victory-messages

The magic points message needs $F1, set when Morph is available, and a bit of $F0, which the loop sets from more than one cause (Terra with Morph, the gil relic); this claim doesn't untangle which. The message texts are in the ROM's battle message table (text/attack_msg.asm), which this pass didn't decode; the names are the disassembly's constants.

Final Fantasy VI's sound effects are numbered $00 to $FC in the disassembly's list, 253 names (18 of them a bare number, unnamed), in a driver table of 256 slots that each point at two channel scripts. The effects have eight samples of their own, apart from the instruments'. In battle a sound is queued and sent once a frame from the NMI as sound driver command $18 with the effect's number and a pan value; the animation scripts' sound command pans by the animation's target position across the screen, and a monster death by the last dying monster's, in formation order. ff6-av/sound-effects

About: Final Fantasy VI Sound effects

The names are the disassembly's; PRE_ names are the sounds before a kind of spell, as the first entries show (Lore, black, white and effect magic, espers). The scripts themselves are generated from MML files the build reads (assets/mml/sfx), so their ROM region starts from an offset (data/rommaps/final-fantasy-vi.yaml, sfx-scripts). Command $C9 with a 0 byte plays the attack's own sound (w7ee9e7). Slots $FD and $FE have no name; $FF means none.

What an ordinary monster's death and a boss's look like on screen, as the color math composes them, is not settled: both set color math to add the sub screen, which holds only sprites, to BG2, and the dying monster's sprites are in palettes 0 to 3; whether the monster shows on the main screen as a darkening figure or only through the add, as a fade into the background, depends on the main screen's layers at the time, which this set hasn't read. ff6-av/death-look