SirStone
a87be5f99f
- Stop-shot gun: predicts enemy deceleration stop point - Catches bots at direction reversal pauses - Battle-tested vs WaveSurfer, Crazy, RandomMover Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
101 lines
3.3 KiB
Nim
101 lines
3.3 KiB
Nim
## Stop-shot gun: predicts the point where a decelerating enemy will stop.
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## Many bots pause briefly when reversing direction — catches them at the stop.
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## Falls back to linear prediction when enemy is not decelerating.
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## Coordinate system: 0° = East, CCW positive (Tank Royale standard).
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import std/math
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import gun_harness/gun_interface
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# TR deceleration constants (px/tick²)
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const BrakeDecel = 2.0 ## same-direction stop
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const CoastDecel = 1.0 ## cross-zero coasting stop
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type StopShotGun* = object
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prevSpeed: float
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prevHeading: float
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prevTick: int
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frames: int
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cachedTick: int
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cachedPredX: float
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cachedPredY: float
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proc initStopShotGun*(): StopShotGun = StopShotGun()
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proc predict*(g: var StopShotGun, state: WorldState, bulletSpeed: float): GunPrediction =
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if bulletSpeed <= 0.0:
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return GunPrediction(x: state.enemyX, y: state.enemyY)
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# Per-tick cache: all power bins share one prediction
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if state.tick == g.cachedTick:
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return GunPrediction(x: g.cachedPredX, y: g.cachedPredY)
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defer:
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g.cachedTick = state.tick
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g.cachedPredX = result.x
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g.cachedPredY = result.y
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# Update history
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let isNew = state.tick > g.prevTick
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if isNew:
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g.prevSpeed = state.enemySpeed
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g.prevHeading = state.enemyHeading
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g.prevTick = state.tick
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inc g.frames
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# Need 2+ frames to detect deceleration
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if g.frames < 2:
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result = GunPrediction(x: state.enemyX, y: state.enemyY)
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return
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let speed = state.enemySpeed
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let prev = g.prevSpeed
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# Detect deceleration: |speed| is shrinking
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let decelerating = abs(speed) < abs(prev) and abs(speed) > 0.01
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if not decelerating:
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# Linear fallback
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let headRad = degToRad(state.enemyHeading)
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let dist = hypot(state.enemyX - state.selfX, state.enemyY - state.selfY)
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let t = dist / bulletSpeed
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var px = state.enemyX + cos(headRad) * speed * t
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var py = state.enemyY + sin(headRad) * speed * t
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result = GunPrediction(
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x: clamp(px, 0.0, state.arenaWidth),
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y: clamp(py, 0.0, state.arenaHeight)
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)
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return
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# Pick decel rate: braking (speed toward zero on same sign) = 2, else 1
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# ponytail: simplified; TR has exact rules per direction but this is close enough
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let decel = if speed * prev > 0.0: BrakeDecel else: CoastDecel
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# Simulate stop position
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let headRad = degToRad(state.enemyHeading)
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var v = speed
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var sx = state.enemyX
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var sy = state.enemyY
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while abs(v) > 0.001:
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sx += v * cos(headRad)
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sy += v * sin(headRad)
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let step = if v > 0.0: -decel else: decel
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v += step
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if (v > 0.0) != (speed > 0.0): v = 0.0 # crossed zero
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# Bullet travel time to current pos, check against ticks to stop
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let dist = hypot(state.enemyX - state.selfX, state.enemyY - state.selfY)
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let bulletTicks = dist / bulletSpeed
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let stopTicks = abs(speed) / decel
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# If bullet arrives well after stop, aim at stop; otherwise linear blend
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let px = if bulletTicks >= stopTicks: sx else: state.enemyX + cos(headRad) * speed * bulletTicks
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let py = if bulletTicks >= stopTicks: sy else: state.enemyY + sin(headRad) * speed * bulletTicks
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result = GunPrediction(
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x: clamp(px, BotRadius, state.arenaWidth - BotRadius),
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y: clamp(py, BotRadius, state.arenaHeight - BotRadius)
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)
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proc onResult*(g: var StopShotGun, e: FeedbackEvent) =
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discard # analytical gun — no learning
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