From a3b4f26b6928de9a324fbf5af42d422c12fb8ba9 Mon Sep 17 00:00:00 2001
From: Davide Cappellini <signorsasso@gmail.com>
Date: Sun, 20 Sep 2026 01:30:21 +0200
Subject: [PATCH] feat(ModularBot): wall-bounce gun, 8 guns total

- Wall-bounce gun: linear extrapolation with arena wall reflection
- Simulates enemy tick-by-tick, bouncing off walls (billiard-ball reflection)
- 4-iteration convergence on ticksToArrive like circular gun
- 8 guns: head-on, linear, circular, tsetlin, guess-factor, pattern, anti-surfer, wall-bounce
- Turret: #CCCCCC (silver), bullet: #EEEEEE (white)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 ModularBot_garage/src/ModularBot.nim | 13 ++++++-
 common_libs/guns/wall_bounce.nim     | 56 ++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+), 2 deletions(-)
 create mode 100644 common_libs/guns/wall_bounce.nim

diff --git a/ModularBot_garage/src/ModularBot.nim b/ModularBot_garage/src/ModularBot.nim
index e99a396..88d92d5 100644
--- a/ModularBot_garage/src/ModularBot.nim
+++ b/ModularBot_garage/src/ModularBot.nim
@@ -17,12 +17,13 @@ import guns/tsetlin
 import guns/guess_factor
 import guns/pattern_matcher
 import guns/anti_surfer
+import guns/wall_bounce
 import movements/phantom_meteor
 
 const botJsonPath = currentSourcePath().parentDir / "ModularBot.json"
 const DebugVBullets = false
 const DebugCircular = false
-const GunNames = ["HeadOn", "Linear", "Tsetlin", "Circular", "GuessFactor", "Pattern", "AntiSurf"]
+const GunNames = ["HeadOn", "Linear", "Tsetlin", "Circular", "GuessFactor", "Pattern", "AntiSurf", "WallBounce"]
 
 type
   ModularBot = ref object of Bot
@@ -38,6 +39,7 @@ type
     guessFactor:  GFGun
     patternMatcher: PatternMatcherGun
     antiSurfer:   AntiSurferGun
+    wallBounce:   WallBounceGun
     mover:        PhantomMeteorModule
     virtualHits:  int
     virtualMiss:  int
@@ -75,6 +77,7 @@ method onScannedBot*(bot: ModularBot, e: ScannedBotEvent) =
   var gfPreds:   array[len(PowerBins), GunPrediction]
   var pmPreds:   array[len(PowerBins), GunPrediction]
   var asPreds:   array[len(PowerBins), GunPrediction]
+  var wbPreds:   array[len(PowerBins), GunPrediction]
   for i in 0..<len(PowerBins):
     headsUp[i]   = bot.headOn.predict(bot.lastState, bulletSpeed(PowerBins[i]))
     linPreds[i]  = bot.linear.predict(bot.lastState, bulletSpeed(PowerBins[i]))
@@ -83,6 +86,7 @@ method onScannedBot*(bot: ModularBot, e: ScannedBotEvent) =
     gfPreds[i]   = bot.guessFactor.predict(bot.lastState, bulletSpeed(PowerBins[i]))
     pmPreds[i]   = bot.patternMatcher.predict(bot.lastState, bulletSpeed(PowerBins[i]))
     asPreds[i]   = bot.antiSurfer.predict(bot.lastState, bulletSpeed(PowerBins[i]))
+    wbPreds[i]   = bot.wallBounce.predict(bot.lastState, bulletSpeed(PowerBins[i]))
 
   bot.tracker.spawnBullets(0, headsUp,   bot.lastState)
   bot.tracker.spawnBullets(1, linPreds,  bot.lastState)
@@ -93,6 +97,7 @@ method onScannedBot*(bot: ModularBot, e: ScannedBotEvent) =
   bot.tracker.spawnBullets(4, gfPreds,   bot.lastState)
   bot.tracker.spawnBullets(5, pmPreds,   bot.lastState)
   bot.tracker.spawnBullets(6, asPreds,   bot.lastState)
+  bot.tracker.spawnBullets(7, wbPreds,   bot.lastState)
 
   # Resolve bullets that have travelled far enough
   let st = bot.lastState
@@ -110,6 +115,7 @@ method onScannedBot*(bot: ModularBot, e: ScannedBotEvent) =
     of 4: bot.guessFactor.onResult(fe)
     of 5: bot.patternMatcher.onResult(fe)
     of 6: bot.antiSurfer.onResult(fe)
+    of 7: bot.wallBounce.onResult(fe)
     else: discard
     if fe.hit: inc bot.virtualHits else: inc bot.virtualMiss
     when DebugVBullets:
@@ -133,6 +139,7 @@ method onScannedBot*(bot: ModularBot, e: ScannedBotEvent) =
     of 4: setTurretColor("#FFCC00"); setBulletColor("#FFE066")  # GuessFactor: yellow
     of 5: setTurretColor("#FF6600"); setBulletColor("#FF9944")  # Pattern: orange
     of 6: setTurretColor("#00CCFF"); setBulletColor("#66DDFF")  # AntiSurf: cyan
+    of 7: setTurretColor("#CCCCCC"); setBulletColor("#EEEEEE")  # WallBounce: silver/white
     else: discard
 
   let pred = case selectedGun
@@ -142,6 +149,7 @@ method onScannedBot*(bot: ModularBot, e: ScannedBotEvent) =
     of 4: bot.guessFactor.predict(bot.lastState, bulletSpeed(power))
     of 5: bot.patternMatcher.predict(bot.lastState, bulletSpeed(power))
     of 6: bot.antiSurfer.predict(bot.lastState, bulletSpeed(power))
+    of 7: bot.wallBounce.predict(bot.lastState, bulletSpeed(power))
     else: bot.headOn.predict(bot.lastState, bulletSpeed(power))
   let target = aimAngle(getX(), getY(), pred.x, pred.y)
 
@@ -201,7 +209,7 @@ method run*(bot: ModularBot) =
 
 when isMainModule:
   var bot = ModularBot(
-    tracker:    vb.initTracker(7),  # 0: HeadOn, 1: Linear, 2: Tsetlin, 3: Circular, 4: GuessFactor, 5: Pattern, 6: AntiSurf
+    tracker:    vb.initTracker(8),  # 0: HeadOn, 1: Linear, 2: Tsetlin, 3: Circular, 4: GuessFactor, 5: Pattern, 6: AntiSurf, 7: WallBounce
     headOn:     HeadOnGun(),
     linear:     LinearGun(),
     circular:   CircularGun(),
@@ -209,6 +217,7 @@ when isMainModule:
     guessFactor: initGFGun(),
     patternMatcher: PatternMatcherGun(),
     antiSurfer:  initAntiSurferGun(),
+    wallBounce:  initWallBounceGun(),
     radar:      RadarLockModule(),
     mover:      initPhantomMeteor(),
     currentGun: -1,
diff --git a/common_libs/guns/wall_bounce.nim b/common_libs/guns/wall_bounce.nim
new file mode 100644
index 0000000..8f4955a
--- /dev/null
+++ b/common_libs/guns/wall_bounce.nim
@@ -0,0 +1,56 @@
+## Wall-bounce gun: linear extrapolation with arena wall reflection.
+## Simulates enemy trajectory tick-by-tick, bouncing off walls like a billiard ball.
+## Coordinate system: 0° = East, CCW positive (Tank Royale standard).
+
+import std/math
+import gun_harness/gun_interface
+
+type WallBounceGun* = object
+  discard
+
+proc initWallBounceGun*(): WallBounceGun = WallBounceGun()
+
+proc simulateBounce(ex, ey, heading, speed: float, ticks: int,
+                    arenaW, arenaH: float): (float, float) =
+  ## Simulate tick-by-tick with wall reflection. Returns final (x, y).
+  const margin = BotRadius
+  var x = ex
+  var y = ey
+  var h = heading  # radians
+  for _ in 0..<ticks:
+    var nx = x + speed * cos(h)
+    var ny = y + speed * sin(h)
+    if nx < margin:
+      nx = margin
+      h = PI - h
+    elif nx > arenaW - margin:
+      nx = arenaW - margin
+      h = PI - h
+    if ny < margin:
+      ny = margin
+      h = -h
+    elif ny > arenaH - margin:
+      ny = arenaH - margin
+      h = -h
+    x = nx
+    y = ny
+  (x, y)
+
+proc predict*(g: var WallBounceGun, state: WorldState, bulletSpeed: float): GunPrediction =
+  let dist = hypot(state.enemyX - state.selfX, state.enemyY - state.selfY)
+  # Iterate ticks estimate 4x to converge
+  var ticks = dist / bulletSpeed
+  for _ in 0..<4:
+    let (px, py) = simulateBounce(
+      state.enemyX, state.enemyY,
+      degToRad(state.enemyHeading), state.enemySpeed,
+      ticks.int, state.arenaWidth, state.arenaHeight)
+    ticks = hypot(px - state.selfX, py - state.selfY) / bulletSpeed
+  let (fx, fy) = simulateBounce(
+    state.enemyX, state.enemyY,
+    degToRad(state.enemyHeading), state.enemySpeed,
+    ticks.int, state.arenaWidth, state.arenaHeight)
+  GunPrediction(x: fx, y: fy)
+
+proc onResult*(g: var WallBounceGun, e: FeedbackEvent) =
+  discard  # analytical gun — no learning