Players can now gain levels by doing things that use their mana

src/main/java/com/minelittlepony/unicopia/entity/player/MagicReserves.java

@@ -42,7 +42,7 @@ public interface MagicReserves {
         /**
          * Adds a percentage increment to this bar's current value
          */
-        default void add(int step) {
+        default void add(float step) {
             set(get() + (step / getMax()));
         }
 

src/main/java/com/minelittlepony/unicopia/entity/player/ManaContainer.java

@@ -9,12 +9,14 @@ public class ManaContainer implements MagicReserves {
     private final Bar energy;
     private final Bar exertion;
     private final Bar mana;
+    private final Bar xp;
 
     public ManaContainer(Pony pony) {
         this.pony = pony;
         this.energy = new BarInst(Pony.ENERGY, 100F);
         this.exertion = new BarInst(Pony.EXERTION, 10F);
-        this.mana = new BarInst(Pony.MANA, 100F);
+        this.xp = new BarInst(Pony.XP, 1);
+        this.mana = new XpCollectingBar(Pony.MANA, 100F);
     }
 
     @Override
@@ -32,6 +34,35 @@ public class ManaContainer implements MagicReserves {
         return mana;
     }
 
+    public Bar getXp() {
+        return xp;
+    }
+
+    class XpCollectingBar extends BarInst {
+
+        XpCollectingBar(TrackedData<Float> marker, float max) {
+            super(marker, max);
+        }
+
+        @Override
+        public void set(float value) {
+            float diff = value - get();
+            if (diff < 0) {
+                if (pony.canLevelUp()) {
+                    xp.add(-diff / (100 * (1 + pony.getCurrentLevel())));
+                    if (xp.getPercentFill() >= 1) {
+                        pony.addLevels(1);
+                        xp.set(0);
+                    }
+                }
+
+                value = get() + diff / (1 + pony.getCurrentLevel());
+            }
+
+            super.set(value);
+        }
+    }
+
     class BarInst implements Bar {
 
         private final TrackedData<Float> marker;

src/main/java/com/minelittlepony/unicopia/entity/player/PlayerPhysics.java

@@ -106,10 +106,12 @@ public class PlayerPhysics extends EntityPhysics<Pony> implements Tickable, Moti
 
             entity.fallDistance = 0;
 
-            if (ticksInAir > 100) {
+            int level = pony.getCurrentLevel() + 1;
+
+            if (ticksInAir > (level * 100)) {
                 Bar mana = pony.getMagicalReserves().getMana();
 
-                mana.add((int)(-getHorizontalMotion(entity) * 50));
+                mana.add((int)(-getHorizontalMotion(entity) * 50 / level));
 
                 if (mana.getPercentFill() < 0.2) {
                     pony.getMagicalReserves().getExertion().add(2);
@@ -156,7 +158,7 @@ public class PlayerPhysics extends EntityPhysics<Pony> implements Tickable, Moti
 
     protected void moveFlying(Entity player, MutableVector velocity) {
 
-        float forward = 0.000015F * (float)Math.sqrt(getHorizontalMotion(player));
+        float forward = 0.000015F * (1 + (pony.getCurrentLevel() / 10F)) * (float)Math.sqrt(getHorizontalMotion(player));
         boolean sneak = !player.isSneaking();
 
         // vertical drop due to gravity

src/main/java/com/minelittlepony/unicopia/entity/player/Pony.java

@@ -45,10 +45,13 @@ import net.minecraft.nbt.CompoundTag;
 import net.minecraft.network.packet.s2c.play.EntityPassengersSetS2CPacket;
 import net.minecraft.server.network.ServerPlayerEntity;
 import net.minecraft.server.world.ServerWorld;
+import net.minecraft.sound.SoundCategory;
+import net.minecraft.sound.SoundEvents;
 import net.minecraft.text.Text;
 import net.minecraft.text.TranslatableText;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.Direction;
+import net.minecraft.util.math.MathHelper;
 import net.minecraft.util.math.Vec3d;
 
 public class Pony implements Caster<PlayerEntity>, Equine<PlayerEntity>, Transmittable, Copieable<Pony> {
@@ -58,6 +61,9 @@ public class Pony implements Caster<PlayerEntity>, Equine<PlayerEntity>, Transmi
     static final TrackedData<Float> ENERGY = DataTracker.registerData(PlayerEntity.class, TrackedDataHandlerRegistry.FLOAT);
     static final TrackedData<Float> EXERTION = DataTracker.registerData(PlayerEntity.class, TrackedDataHandlerRegistry.FLOAT);
     static final TrackedData<Float> MANA = DataTracker.registerData(PlayerEntity.class, TrackedDataHandlerRegistry.FLOAT);
+    static final TrackedData<Float> XP = DataTracker.registerData(PlayerEntity.class, TrackedDataHandlerRegistry.FLOAT);
+
+    static final TrackedData<Integer> LEVEL = DataTracker.registerData(PlayerEntity.class, TrackedDataHandlerRegistry.INTEGER);
 
     private static final TrackedData<CompoundTag> EFFECT = DataTracker.registerData(PlayerEntity.class, TrackedDataHandlerRegistry.TAG_COMPOUND);
     private static final TrackedData<CompoundTag> HELD_EFFECT = DataTracker.registerData(PlayerEntity.class, TrackedDataHandlerRegistry.TAG_COMPOUND);
@@ -92,6 +98,7 @@ public class Pony implements Caster<PlayerEntity>, Equine<PlayerEntity>, Transmi
         player.getDataTracker().startTracking(RACE, Race.HUMAN.ordinal());
         player.getDataTracker().startTracking(EFFECT, new CompoundTag());
         player.getDataTracker().startTracking(HELD_EFFECT, new CompoundTag());
+        player.getDataTracker().startTracking(LEVEL, 0);
     }
 
     public static void registerAttributes(DefaultAttributeContainer.Builder builder) {
@@ -293,6 +300,20 @@ public class Pony implements Caster<PlayerEntity>, Equine<PlayerEntity>, Transmi
         prevLanded = entity.isOnGround();
     }
 
+    @Override
+    public void addLevels(int levels) {
+        if (levels > 0) {
+            mana.getMana().set(mana.getEnergy().getMax());
+            entity.world.playSound(null, getOrigin(), SoundEvents.ENTITY_PLAYER_LEVELUP, SoundCategory.PLAYERS, 1, 2);
+        }
+        Caster.super.addLevels(levels);
+    }
+
+    @Override
+    public int getMaxLevel() {
+        return 3;
+    }
+
     public Optional<Float> onImpact(float distance, float damageMultiplier) {
 
         float g = gravity.getGravityModifier();
@@ -426,11 +447,12 @@ public class Pony implements Caster<PlayerEntity>, Equine<PlayerEntity>, Transmi
 
     @Override
     public int getCurrentLevel() {
-        return 0;
+        return entity.getDataTracker().get(LEVEL);
     }
 
     @Override
     public void setCurrentLevel(int level) {
+        entity.getDataTracker().set(LEVEL, MathHelper.clamp(level, 0, getMaxLevel()));
     }
 
     public boolean isClientPlayer() {