megadev-effects

Megadev effects

Effects add feedback to the game's existing mechanics and art direction. Adapt these techniques to the user's brief; the Lab's lantern, weather, colors, sound and controls are illustrative.

• Read Pools and simulation for finite lifetimes,

deterministic timing, burst admission, pause and decorative degradation.

• Read Rendering and performance for resident tiles,

SAT/scanline budgets, presentation-only shake and one VBlank publisher.

• Read Validation for behavior tests, original-68000

execution, ARM64/AMD64 comparison, regional checks and measurement limits.

Use ewrogers/megadev:latest and inspect the selected image's source. Megadev exposes VDP and BIOS facilities; this skill's fx_* functions are application code, not a particle engine supplied by the SDK. Do not introduce SGDK's sprite, DMA queue, resource compiler or task APIs as Megadev calls.

Essential choices:

• Reserve room for gameplay and important impacts before decorative weather.

Bound particles, emission per update, simulation catch-up, submitted sprites, per-scanline work and bytes published. A finite pool alone is not a frame budget.

• Keep transient effects allocation-free when a fixed pool fits. Define the

full-pool behavior explicitly: reject, replace a less important effect, or reduce emission. Never evict gameplay entities to show decoration.

• Use the game's existing clock and input edge handling. Pause and slow motion

are deliberate policies; do not multiply speeds by the measured render FPS.

• Keep effect art resident where useful. Animate by choosing existing tiles;

account for remaining VRAM, palette and SAT costs even if no tiles are uploaded.

• Build an immutable frame snapshot outside interrupts. Submit through the

existing VDP owner, in a measured safe interval. Avoid active-display palette writes and unbounded work in a callback.

• Apply shake to camera presentation, not simulation positions or collision.

Keep HUD panels stable and restore scroll offsets when the envelope ends.

The standalone Effects Lab demonstrates these choices. scripts/create_project.py creates a fresh project without replacing files. Its separate burst/trail/weather pools and conservative H40 renderer are one policy, not mandatory capacities or an all-purpose sprite scheduler.

Reuse megadev-graphics for renderer integration and palette ownership, megadev-animation for gameplay animation events, megadev-gameplay for game rules, megadev-audio for the sound owner, and megadev-performance for broader profiling. Effects must not install competing VDP, drive, clock or audio owners.