SirStone
18ff2d45b3
- Accel gun: tracks velocity+heading changes, extrapolates with acceleration - Handles speed-up, slow-down, and combined accel+turn - Battle-tested vs Crazy, RandomMover, Walls
93 lines
2.9 KiB
Nim
93 lines
2.9 KiB
Nim
## Acceleration predictor gun: tracks velocity and heading changes across frames,
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## extrapolates with accel+turn for bots that speed up/slow down.
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## Needs 3+ frames for stable accel; falls back to linear (2 frames) or head-on (1 frame).
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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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const MaxSpeed = 8.0 ## TR bot max speed (px/tick)
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type AccelGun* = object
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prevSpeed: float
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prevHeading: float
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prevPrevSpeed: float
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prevTick: int
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frames: int ## how many observations we have
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cachedAccel: float ## accel (px/tick²) cached per tick
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cachedTurnRate: float ## turn rate (deg/tick) cached per tick
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cachedTick: int
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proc initAccelGun*(): AccelGun =
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AccelGun()
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proc predict*(g: var AccelGun, 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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# Update observation window on new tick
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if state.tick > g.cachedTick:
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if g.frames >= 1:
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# Compute turn rate (normalised to [-180, 180])
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var tr = state.enemyHeading - g.prevHeading
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if tr > 180.0: tr -= 360.0
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elif tr < -180.0: tr += 360.0
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let tickDelta = max(1, state.tick - g.prevTick).float
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g.cachedTurnRate = tr / tickDelta
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if g.frames >= 2:
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# Compute acceleration
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g.cachedAccel = (state.enemySpeed - g.prevSpeed) / tickDelta
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else:
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g.cachedAccel = 0.0
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else:
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g.cachedTurnRate = 0.0
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g.cachedAccel = 0.0
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# Advance window
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g.prevPrevSpeed = g.prevSpeed
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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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g.cachedTick = state.tick
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inc g.frames
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# fallback: not enough history
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if g.frames < 2:
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return GunPrediction(x: state.enemyX, y: state.enemyY)
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let dx = state.enemyX - state.selfX
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let dy = state.enemyY - state.selfY
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let dist = sqrt(dx*dx + dy*dy)
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var t = dist / bulletSpeed # initial ticks estimate
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let accel = g.cachedAccel
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let turnRate = g.cachedTurnRate # deg/tick
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# Iterative convergence (same pattern as circular gun)
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var ex = state.enemyX
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var ey = state.enemyY
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for _ in 0..4:
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var vx = state.enemySpeed
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var hd = state.enemyHeading # degrees
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var px = state.enemyX
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var py = state.enemyY
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let iters = int(t + 0.5)
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for _ in 0..<iters:
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vx = clamp(vx + accel, -MaxSpeed, MaxSpeed)
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hd += turnRate
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let hr = degToRad(hd)
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px += vx * cos(hr)
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py += vx * sin(hr)
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# Clamp to arena
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ex = clamp(px, BotRadius, state.arenaWidth - BotRadius)
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ey = clamp(py, BotRadius, state.arenaHeight - BotRadius)
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let ndx = ex - state.selfX
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let ndy = ey - state.selfY
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t = sqrt(ndx*ndx + ndy*ndy) / bulletSpeed
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GunPrediction(x: ex, y: ey)
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proc onResult*(g: var AccelGun, e: FeedbackEvent) =
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discard # analytical gun — no learning
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