RPG spell timeline and fireball example

Play the project to cast a reusable seven-layer Fireball: casting sigil, moving core, travelling embers, impact flash, sparks, aftermath smoke and residual glow. Its embedded TimelineAsset owns the Cast, Launch, Impact and Aftermath markers. Eleven typed property/event tracks use the same compiler and director as scene sequences. The startup scene is Combat.epokmap. BP_Fireball spawns the effect directly, waits for its embedded timeline's Impact, applies damage once to the captured target, then waits for the particle tail to drain. Native code supplies input and HUD updates; the Blueprint owns the spell choreography's connection to combat. The target starts at 100 HP and each Impact deals 25 damage.

The first spell casts automatically. Cross casts again after completion, Circle cancels the current effect, Square reloads the combat scene, and Start pauses/resumes. Cancelling before Impact leaves HP unchanged. Destroying the caster or replacing the scene cancels its continuation without running damage or completion gameplay. The target's authoring UUID becomes a generation-checked handle captured at cast time; changing the next cast's target cannot redirect an already suspended Impact.

Open assets/blueprints/BP_Fireball.epokbp to inspect the cast and cancellation graphs. tests/fixtures/create_timeline_combat.py explicitly regenerates that Blueprint and scene with stable IDs; native declarations remain in SpellCombat.

Open assets/Effects/Fireball.particle-effect.json to edit density, violence, scale, brightness, chaos, direction and duration, then preview with pause, restart, seek, camera/background controls and visible particle/drop counters. The atlas is the original MIT-licensed artwork from rpg-2-5d-demo. The explicit fixture generator tests/fixtures/create_timeline_fireball.py recreates the effect/texture source with stable IDs; it overwrites those example files when run.

The final authored burst uses 32 sparks. PCSX measured a peak of 51 particles, 76 particles emitted over the whole effect, no dropped particles/sprite work, and complete cleanup. The largest completed-frame simulation sample was 182 scanlines. This is an emulator fixture measurement, not a hardware or 60 FPS guarantee. Host/MIPS comparison covers all 350 steps, including sprite values.

The separate Main.epokmap retains the original presentation harness and scene TimelineComponent example. Open Timeline Spell.epokproject, then double-click Cast.timeline.json in the Project browser. Scrub the preview: charge rises from zero to one at Impact, falls to 0.25 at Aftermath, and reaches zero at completion. Validate reports the empty required Caster binding; choose the scene's Caster in Test scene binding. These test bindings are temporary and never enter the reusable asset.

The Reset Charge event calls an explicitly exposed idempotent presentation action at tick 4096. Its Fixed argument cooks to raw Q12. Scrubbing previews property values and never invokes C++ actions or gameplay code.

The Caster has a TimelineComponent bound to this asset and to its own authored UUID. Play runs the compiled charge curve and Reset Charge event. Inspect the component to change its asset, bindings, enable state, or automatic playback. The charge property currently has no visual output; it remains a small scene sequence example alongside the Fireball combat scene.

From the engine repository after building both binaries:

target/debug/epok-editor.exe --project examples/timeline-spell --compile-timelines
target/debug/epok-editor.exe --project examples/timeline-spell --open-timeline assets/Timelines/Cast.timeline.json
target/debug/epok-editor.exe --project examples/timeline-spell --open-effect assets/Effects/Fireball.particle-effect.json
target/debug/epok-editor.exe --project examples/timeline-spell --open-blueprint assets/blueprints/BP_Fireball.epokbp
target/debug/epok-editor.exe --project examples/timeline-spell --build-psx

The scene binding's class UUID and the track's property UUID refer to the annotated SpellPresentation declaration. Renaming labels preserves those identities. Removing TimelineAnimatable must fail validation, even though the property remains editable.