Rank based speed limiter for catch-up

core/src/com/agateau/pixelwheels/GamePlay.java

@@ -52,6 +52,8 @@ public class GamePlay {
     // speed
     public float aiSpeedLimiter = 0.8f;
 
+    public float extremeSpeedLimiter = 0.5f;
+
     public boolean oneLapOnly = false;
     public boolean freeCamera = false;
 

core/src/com/agateau/pixelwheels/racer/AIPilot.java

@@ -197,17 +197,6 @@ private void updateAcceleration() {
         Vehicle vehicle = mRacer.getVehicle();
         vehicle.setAccelerating(true);
         vehicle.setBraking(false);
-
-        // If we are better ranked than a player, slow down a bit
-        boolean needLimit = false;
-        for (Racer playerRacer : mGameWorld.getPlayerRacers()) {
-            if (Racer.compareRaceDistances(mRacer, playerRacer) > 0) {
-                needLimit = true;
-                break;
-            }
-        }
-        float limit = needLimit ? GamePlay.instance.aiSpeedLimiter : 1f;
-        vehicle.setSpeedLimiter(limit);
     }
 
     private void updateDirection() {

core/src/com/agateau/pixelwheels/racer/Vehicle.java

@@ -255,6 +255,10 @@ public void setSpeedLimiter(float speedLimiter) {
         mSpeedLimiter = speedLimiter;
     }
 
+    public float getSpeedLimiter() {
+        return mSpeedLimiter;
+    }
+
     /** Returns the angle the car is facing */
     public float getAngle() {
         return AgcMathUtils.normalizeAngle(mBody.getAngle() * MathUtils.radiansToDegrees);

core/src/com/agateau/pixelwheels/racescreen/GameWorldImpl.java

@@ -20,6 +20,7 @@
 
 import com.agateau.pixelwheels.Assets;
 import com.agateau.pixelwheels.Constants;
+import com.agateau.pixelwheels.GamePlay;
 import com.agateau.pixelwheels.GameWorld;
 import com.agateau.pixelwheels.PwGame;
 import com.agateau.pixelwheels.bonus.Bonus;
@@ -183,6 +184,40 @@ public GameStats getGameStats() {
 
     @Override
     public void act(float delta) {
+        // limit speed one before another, propotional to the distance between them
+        final int distancePerLap = mTrack.getLapPositionTable().getSectionCount();
+        mRacers.sort(sRacerComparator);
+        Racer racerBehind = null;
+        for (int i = mRacers.size - 1; i >= 0; i--) {
+            final Racer racer = mRacers.get(i);
+            if (racer.getLapPositionComponent().hasFinishedRace()) {
+                break; // this racer has finished, all racers ahead of it must have finished too
+            }
+            if (racerBehind == null) {
+                racer.getVehicle().setSpeedLimiter(1);
+            } else {
+                final LapPositionComponent p1 = racer.getLapPositionComponent();
+                final LapPositionComponent p2 = racerBehind.getLapPositionComponent();
+                final float ddiff =
+                        (p1.getLapCount() - p2.getLapCount()) * distancePerLap
+                                + p1.getLapDistance()
+                                - p2.getLapDistance();
+                assert ddiff >= 0;
+                if (ddiff > distancePerLap) {
+                    // more than one lap, spare the aheader for speed limit
+                    racer.getVehicle().setSpeedLimiter(1);
+                } else {
+                    racer.getVehicle()
+                            .setSpeedLimiter(
+                                    racerBehind.getVehicle().getSpeedLimiter()
+                                            * Math.max(
+                                                    GamePlay.instance.extremeSpeedLimiter,
+                                                    1.0f - ddiff / distancePerLap));
+                }
+            }
+            racerBehind = racer;
+        }
+
         // fixed time step
         // max frame time to avoid spiral of death (on slow devices)
         float frameTime = Math.min(delta, 0.25f);
@@ -214,7 +249,6 @@ public void act(float delta) {
         }
 
         if (haveAllRacersFinished()) {
-            mRacers.sort(sRacerComparator);
             setState(GameWorld.State.FINISHED);
         }
     }