Task 040: Engine Burn Visualization in Interactive Orbital Diagrams

Status: DONE

Motivation

Human directive: "インタラクティブ軌道遷移グラフにおいて、エンジン点火の描写がほしい"

Implementation (Codex design-reviewed)

BurnMarker Type Extension

• Added BurnType = "acceleration" | "deceleration" | "midcourse" | "capture"
• Added startTime?, endTime? (transfer-relative seconds), type? to BurnMarker
• Fully backward-compatible: existing static markers still work

Animation Engine (orbital-animation.js)

• Exhaust plume: SVG wedge polygon trailing ship marker, oriented via path tangent
• Path tangent computed from getPointAtLength(s±eps) finite differences
• Burn type → color mapping: acceleration=orange, deceleration=cyan, midcourse=yellow, capture=magenta
• Plume flicker: subtle opacity oscillation (0.75 + 0.25·sin(20t))
• Ship marker enlarges (r=6) and glows with burn color during active thrust
• Burn label text displayed above ship during active burns
• Brachistochrone fallback: auto-infers acc/dec halves when no explicit burns

Templates

• Animation JSON now includes burns[] per transfer and style field
• CSS: .burn-plume, .burn-label-text classes

Episode Data Updates

All animated diagrams now have burn timing:

• EP01: 3 burns (acc + midcourse turnover + dec, 72h brachistochrone)
• EP02: 2 burns (departure impulse, capture impulse)
• EP03: 3 burns (acc + dec brachistochrone, capture impulse)
• EP04: 3 burns (65% thrust acc + dec, departure impulse)
• EP05: 2 burns (acc + dec, 8.3d @300t brachistochrone)

Tests

• 6 new tests in templates.test.ts (burns in animation JSON, filtering, CSS)
• 820 TS + 79 Rust = 899 total, 0 failures

Depends on

• Interactive orbital animation (Task 019) — DONE
• Report types and templates (report-types.ts, templates.ts)