An ability will now show how much mana it will cost before activating

src/main/java/com/minelittlepony/unicopia/ability/Ability.java

@@ -10,6 +10,12 @@ import net.minecraft.util.Identifier;
 import net.minecraft.world.World;
 
 public interface Ability<T extends Hit> {
+
+    /**
+     * The amount of energy this ability is expected to cost if the player were to cast it.
+     */
+    double getCostEstimate(Pony player);
+
     /**
      * Returns the number of ticks the player must hold the ability key to trigger this ability.
      */

src/main/java/com/minelittlepony/unicopia/ability/AbilityDispatcher.java

@@ -1,10 +1,10 @@
 package com.minelittlepony.unicopia.ability;
 
+import java.util.Collection;
 import java.util.Collections;
 import java.util.EnumMap;
 import java.util.Map;
 import java.util.Optional;
-
 import javax.annotation.Nullable;
 
 import com.minelittlepony.unicopia.Race;
@@ -47,6 +47,10 @@ public class AbilityDispatcher implements Tickable, NbtSerialisable {
         }
     }
 
+    public Collection<Stat> getStats() {
+        return stats.values();
+    }
+
     public Stat getStat(AbilitySlot slot) {
         return stats.computeIfAbsent(slot, Stat::new);
     }
@@ -141,6 +145,13 @@ public class AbilityDispatcher implements Tickable, NbtSerialisable {
             return maxWarmup <= 0 ? 0 : ((float)warmup / (float)maxWarmup);
         }
 
+        public double getCost(long page) {
+            if (warmup <= 0) {
+                return 0;
+            }
+            return getAbility(page).map(ability -> ability.getCostEstimate(player)).orElse(0D);
+        }
+
         public void setWarmup(int value) {
             maxWarmup = value;
             warmup = value;

src/main/java/com/minelittlepony/unicopia/ability/BatEeeeAbility.java

@@ -35,6 +35,11 @@ public class BatEeeeAbility implements Ability<Hit> {
         return 1;
     }
 
+    @Override
+    public double getCostEstimate(Pony player) {
+        return 0;
+    }
+
     @Override
     public boolean canUse(Race race) {
         return race == Race.BAT;

src/main/java/com/minelittlepony/unicopia/ability/BatPonyHangAbility.java

@@ -27,6 +27,11 @@ public class BatPonyHangAbility implements Ability<Multi> {
         return 0;
     }
 
+    @Override
+    public double getCostEstimate(Pony player) {
+        return 0;
+    }
+
     @Override
     public boolean canUse(Race race) {
         return race == Race.BAT;

src/main/java/com/minelittlepony/unicopia/ability/CarryAbility.java

@@ -25,6 +25,11 @@ public class CarryAbility implements Ability<Hit> {
         return 10;
     }
 
+    @Override
+    public double getCostEstimate(Pony player) {
+        return 0;
+    }
+
     @Override
     public boolean canUse(Race race) {
         return race.canFly();

src/main/java/com/minelittlepony/unicopia/ability/ChangelingFeedAbility.java

@@ -88,6 +88,11 @@ public class ChangelingFeedAbility implements Ability<Hit> {
         return list.stream().map(i -> (LivingEntity)i).collect(Collectors.toList());
     }
 
+    @Override
+    public double getCostEstimate(Pony player) {
+        return 0;
+    }
+
     @Override
     public void apply(Pony iplayer, Hit data) {
         PlayerEntity player = iplayer.getMaster();

src/main/java/com/minelittlepony/unicopia/ability/EarthPonyGrowAbility.java

@@ -44,6 +44,11 @@ public class EarthPonyGrowAbility implements Ability<Pos> {
         return Pos.SERIALIZER;
     }
 
+    @Override
+    public double getCostEstimate(Pony player) {
+        return 10;
+    }
+
     @Override
     public void apply(Pony player, Pos data) {
         int count = 0;

src/main/java/com/minelittlepony/unicopia/ability/EarthPonyStompAbility.java

@@ -66,6 +66,11 @@ public class EarthPonyStompAbility implements Ability<Multi> {
         return race.canUseEarth();
     }
 
+    @Override
+    public double getCostEstimate(Pony player) {
+        return rad;
+    }
+
     @Nullable
     @Override
     public Multi tryActivate(Pony player) {
@@ -91,7 +96,6 @@ public class EarthPonyStompAbility implements Ability<Multi> {
         return null;
     }
 
-
     @Override
     public Hit.Serializer<Multi> getSerializer() {
         return Multi.SERIALIZER;

src/main/java/com/minelittlepony/unicopia/ability/UnicornCastingAbility.java

@@ -40,6 +40,21 @@ public class UnicornCastingAbility implements Ability<Hit> {
         return Hit.SERIALIZER;
     }
 
+    @Override
+    public double getCostEstimate(Pony player) {
+        if (player.hasSpell()) {
+            String current = player.getSpell(true).getName();
+            String replaced = Streams.stream(player.getMaster().getItemsHand())
+                    .map(SpellRegistry::getKeyFromStack)
+                    .filter(i -> i != null && !current.equals(i))
+                    .findFirst()
+                    .orElse(null);
+            return replaced == null ? 2 : 4;
+        }
+
+        return 4;
+    }
+
     @Override
     public void apply(Pony player, Hit data) {
 

src/main/java/com/minelittlepony/unicopia/ability/UnicornProjectileAbility.java

@@ -53,9 +53,14 @@ public class UnicornProjectileAbility implements Ability<Hit> {
         return Hit.SERIALIZER;
     }
 
+    @Override
+    public double getCostEstimate(Pony player) {
+        return 7;
+    }
+
     @Override
     public void apply(Pony player, Hit data) {
-        player.subtractEnergyCost(7);
+        player.subtractEnergyCost(getCostEstimate(player));
         getThrown(player).orElseGet(AttractiveSpell::new).toss(player);
     }
 

src/main/java/com/minelittlepony/unicopia/ability/UnicornTeleportAbility.java

@@ -54,6 +54,16 @@ public class UnicornTeleportAbility implements Ability<Pos> {
         return race.canCast();
     }
 
+    @Override
+    public double getCostEstimate(Pony player) {
+        Pos pos = tryActivate(player);
+
+        if (pos == null) {
+            return 0;
+        }
+        return pos.distanceTo(player) / 10;
+    }
+
     @Override
     public Pos tryActivate(Pony player) {
         int maxDistance = player.getMaster().isCreative() ? 1000 : 100;
@@ -118,7 +128,7 @@ public class UnicornTeleportAbility implements Ability<Pos> {
         iplayer.getWorld().playSound(null, iplayer.getOrigin(), SoundEvents.ENTITY_ITEM_PICKUP, SoundCategory.PLAYERS, 1, 1);
 
         PlayerEntity player = iplayer.getMaster();
-        double distance = Math.sqrt(player.squaredDistanceTo(data.x, data.y, data.z)) / 10;
+        double distance = data.distanceTo(iplayer) / 10;
 
         if (player.hasVehicle()) {
             Entity mount = player.getVehicle();

src/main/java/com/minelittlepony/unicopia/ability/data/Pos.java

@@ -1,5 +1,7 @@
 package com.minelittlepony.unicopia.ability.data;
 
+import com.minelittlepony.unicopia.ability.magic.Caster;
+
 import net.minecraft.network.PacketByteBuf;
 import net.minecraft.util.math.BlockPos;
 
@@ -39,4 +41,8 @@ public class Pos extends Hit {
     public BlockPos pos() {
         return new BlockPos(x, y, z);
     }
+
+    public double distanceTo(Caster<?> caster) {
+        return Math.sqrt(caster.getEntity().squaredDistanceTo(x, y, z));
+    }
 }

src/main/java/com/minelittlepony/unicopia/client/gui/ManaRingSlot.java

@@ -2,6 +2,7 @@ package com.minelittlepony.unicopia.client.gui;
 
 import com.minelittlepony.unicopia.ability.AbilityDispatcher;
 import com.minelittlepony.unicopia.ability.AbilitySlot;
+import com.minelittlepony.unicopia.client.KeyBindingsHandler;
 import com.minelittlepony.unicopia.entity.player.MagicReserves;
 import com.minelittlepony.unicopia.entity.player.Pony;
 import com.minelittlepony.unicopia.entity.player.MagicReserves.Bar;
@@ -32,6 +33,27 @@ class ManaRingSlot extends Slot {
         double arcBegin = 0;
 
         arcBegin = renderRing(matrices, 17, 13, 0, mana.getMana(), 0xFF88FF99);
+
+        if (!uHud.client.player.isCreative()) {
+            double cost = abilities.getStats().stream()
+                    .mapToDouble(s -> s.getCost(KeyBindingsHandler.INSTANCE.page))
+                    .reduce(Double::sum)
+                    .getAsDouble();
+
+            if (cost > 0) {
+                float percent = mana.getMana().getPercentFill();
+                float max = mana.getMana().getMax();
+
+                cost = Math.min(max, cost) / max;
+
+                cost = Math.min(percent, cost);
+
+                double angle = cost * Math.PI * 2;
+
+                renderArc(matrices, 13, 17, arcBegin - angle, angle, 0xFFFF0099, false);
+            }
+        }
+
         arcBegin = renderRing(matrices, 17, 13, arcBegin, mana.getEnergy(), 0xFF002299);
 
         matrices.pop();
@@ -42,7 +64,7 @@ class ManaRingSlot extends Slot {
     private double renderRing(MatrixStack matrices, double outerRadius, double innerRadius, double offsetAngle, Bar bar, int color) {
         double fill = bar.getPercentFill() * Math.PI * 2;
 
-        renderArc(matrices, innerRadius, outerRadius, offsetAngle, fill, color, false);
+        renderArc(matrices, innerRadius, outerRadius, offsetAngle, fill, color, true);
         return offsetAngle + fill;
     }
 

src/main/java/com/minelittlepony/unicopia/client/gui/Slot.java

@@ -67,7 +67,7 @@ class Slot {
         uHud.renderAbilityIcon(matrices, abilities.getStat(bSwap ? bSlot : aSlot), slotPadding / 2, slotPadding / 2, iconSize, iconSize, iconSize, iconSize);
 
 
-        if (cooldown > 0 && cooldown < 1) {
+        if (cooldown > 0 && cooldown <= 1) {
             float lerpCooldown = MathHelper.lerp(tickDelta, cooldown, lastCooldown);
 
             lastCooldown = lerpCooldown;

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

@@ -305,7 +305,7 @@ public class Pony implements Caster<PlayerEntity>, Equine<PlayerEntity>, Transmi
         }
 
         if (!getSpecies().canFly() || !gravity.isFlying()) {
-            mana.getMana().add(60);
+            mana.getMana().add(15);
         }
 
         attributes.applyAttributes(this);
@@ -368,7 +368,7 @@ public class Pony implements Caster<PlayerEntity>, Equine<PlayerEntity>, Transmi
 
     @Override
     public boolean subtractEnergyCost(double foodSubtract) {
-        if (!entity.abilities.creativeMode) {
+        if (!entity.isCreative()) {
 
             float currentMana = mana.getMana().get();
             float foodManaRatio = 10;