Entry 69

Positional sound: the falloff, the pan and Mono

3maudio

This entry answers what was left open by question 1 of Title: the Audio menu.

Filescrates/rugrats/src/world/game/mod.rs crates/rugrats/src/audio/sound.rs crates/rugrats/src/app/mod.rs docs/engine/front-end.md

World sounds now follow 0x8006f644 (docs/engine/front-end.md, The positional sounds). Before, the port faded the player's sounds linearly to 16384 from the eye, with no pan, and the Audio menu's Mono did nothing.

  • Game::play_at(sound, pos):
    • The distance from the camera is dx^2/16384 + dy^2/4096 + dz^2/16384.
    • The falloff (0x8006fd68, table 0x800b8024: 128, 16384, 127) is capped by the effects setting.
    • Unless Mono, it is split by 0x8006fc40: about a third lost from behind, and the far side up to three quarters.
  • Effect is { sound, at: Option<(left, right)> }. A world sound carries its own volumes; the rest play at the effects setting, as before.
  • Spu::effect takes (left, right) like SsUtKeyOn's voll and volr, on top of the tone's and program's volume and pan.
  • The player's sounds (take-off, landing, steps) go through play_at.
  • Test: world::game::tests::positional_falloff (the table's steps).
Still unknown
  1. Which other sounds the original plays positionally (NPCs, doors, objects). The port still plays those at full volume, centred.
  2. The bearing (0x80021590) is computed in floating point here, not from the original's arctangent table.