Smoother keyboard movement using ticks instead of key repeat polling

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

lib/main.dart

@@ -1,5 +1,6 @@
 import "dart:math" as math;
 
+import "package:flutter/scheduler.dart";
 import "package:flutter/services.dart";
 import "package:flutter/widgets.dart";
 
@@ -151,19 +152,29 @@ class Player extends StatefulWidget {
   final ValueChanged<Offset> onPositionUpdated;
   final RayData rayData;
 
-  /// How "fast" the player moves
+  /// Length of the player's direction line on the minimap.
   static const int speed = 5;
 
+  /// Turning speed in radians per second, applied every frame.
+  static const double turnRate = 3.5;
+
+  /// Movement speed in pixels per second, applied every frame.
+  static const double moveSpeed = 100;
+
   @override
   State<Player> createState() => _PlayerState();
 }
 
-class _PlayerState extends State<Player> {
+class _PlayerState extends State<Player> with SingleTickerProviderStateMixin {
+  late final Ticker _ticker;
+  Duration _lastElapsed = Duration.zero;
+
   @override
   void initState() {
     super.initState();
 
-    HardwareKeyboard.instance.addHandler(keyPressHandler);
+    HardwareKeyboard.instance.addHandler(_consumeKey);
+    _ticker = createTicker(_tick)..start();
 
     WidgetsBinding.instance.addPostFrameCallback((_) {
       widget.onRaysUpdated(
@@ -185,8 +196,20 @@ class _PlayerState extends State<Player> {
 
   @override
   void dispose() {
+    HardwareKeyboard.instance.removeHandler(_consumeKey);
+    _ticker.dispose();
     super.dispose();
-    HardwareKeyboard.instance.removeHandler(keyPressHandler);
+  }
+
+  bool _consumeKey(KeyEvent event) {
+    switch (event.logicalKey) {
+      case LogicalKeyboardKey.keyA:
+      case LogicalKeyboardKey.keyD:
+      case LogicalKeyboardKey.keyW:
+      case LogicalKeyboardKey.keyS:
+        return true;
+    }
+    return false;
   }
 
   /// Get the map tile at a given pixel coordinate
@@ -225,60 +248,68 @@ class _PlayerState extends State<Player> {
     return choices.first;
   }
 
-  bool keyPressHandler(KeyEvent event) {
+  /// Advances the player once per frame based on the keys currently held.
+  void _tick(Duration elapsed) {
+    final double dt = math.min(
+      (elapsed - _lastElapsed).inMicroseconds / Duration.microsecondsPerSecond,
+      0.05,
+    );
+    _lastElapsed = elapsed;
+
     final Set<LogicalKeyboardKey> keys =
         HardwareKeyboard.instance.logicalKeysPressed;
 
-    bool handled = false;
-
     // Where is the player now?
     Offset playerPosition = widget.rayData.playerPosition;
+    double playerAngle = widget.rayData.playerAngle;
+
+    bool hasMoved = false;
+
+    // Turn the player.
+    final bool turningLeft = keys.contains(LogicalKeyboardKey.keyA);
+    final bool turningRight = keys.contains(LogicalKeyboardKey.keyD);
+    if (turningLeft != turningRight) {
+      playerAngle += (turningRight ? 1 : -1) * Player.turnRate * dt;
+      playerAngle = playerAngle.normalizeAngle;
+      hasMoved = true;
+    }
+
+    // Capture the direction *after* any turn this frame.
+    final Offset direction = playerAngle.direction;
     final Offset playerCenter =
         playerPosition +
         Offset(GameMap.dimensions.width / 2, GameMap.dimensions.height / 2);
-    double playerAngle = widget.rayData.playerAngle;
 
     // How many pixels away from a wall to stay
-    const double buffer = 2;
+    const double wallDistanceBuffer = 2.5;
 
-    if (keys.contains(LogicalKeyboardKey.keyA)) {
-      // Turn left
-      playerAngle -= 0.1;
-      handled = true;
-    } else if (keys.contains(LogicalKeyboardKey.keyD)) {
-      // Turn right
-      playerAngle += 0.1;
-      handled = true;
-    }
+    final bool movingForward = keys.contains(LogicalKeyboardKey.keyW);
+    final bool movingBackward = keys.contains(LogicalKeyboardKey.keyS);
+    if (movingForward != movingBackward) {
+      final double travel = Player.moveSpeed * dt;
 
-    // Capture the direction *after* it's potentially mutated
-    final Offset direction = playerAngle.direction;
-
-    if (keys.contains(LogicalKeyboardKey.keyW)) {
-      if (safeDistanceToWall(playerCenter, direction) > Player.speed + buffer) {
-        // Move forward
-        playerPosition += playerAngle.playerDelta;
+      if (movingForward) {
+        if (safeDistanceToWall(playerCenter, direction) >
+            travel + wallDistanceBuffer) {
+          // Move forward
+          playerPosition += direction * travel;
+          hasMoved = true;
+        }
+      } else if (safeDistanceToWall(playerCenter, -direction) >
+          travel + wallDistanceBuffer) {
+        // Move backwards
+        playerPosition -= direction * travel;
+        hasMoved = true;
       }
-      handled = true;
-    } else if (keys.contains(LogicalKeyboardKey.keyS)) {
-      if (safeDistanceToWall(playerCenter, -direction) >
-          Player.speed + buffer) {
-        // Move backwwards
-        playerPosition -= playerAngle.playerDelta;
-      }
-      handled = true;
     }
 
-    if (handled) {
-      widget.onRaysUpdated(
-        calculateRays(playerPosition, playerAngle),
-      );
-      widget.onAngleUpdated(playerAngle);
-      widget.onPositionUpdated(playerPosition);
-      return true;
-    }
+    if (!hasMoved) return;
 
-    return false;
+    widget.onRaysUpdated(
+      calculateRays(playerPosition, playerAngle),
+    );
+    widget.onAngleUpdated(playerAngle);
+    widget.onPositionUpdated(playerPosition);
   }
 
   List<Ray> calculateRays(Offset offset, double playerAngle) {