Rework Root Target.

This commit completely reworks the Root Target ability implementation by
replacing the repeated teleportation code with potion effects.

The old implementation relied on teleporting the target every tick for a
given duration, but because teleporting also involves pitch and yaw, the
result was a constant "snapping back in place" experience.

The new implementation works by applying the following potion effects
with a very large amplification:

- Slowness, to prevent the player from moving out of place.
- Slow falling, to negate fall damage.
- Negative jump boost, to prevent the player from jumping around.

Note that the jump boost uses a _negative_ amplification to make it have
the inverse effect, i.e. a much worse jump ability. It is still possible
to jump an arguably negligible amount away from the root location.

Fixes #490

changelog.md

@@ -15,6 +15,7 @@ These changes will (most likely) be included in the next version.
 - Arena signs now support dynamic list entry variables for 4 different player lists. As an example, `<notready-1>` results in the name of a player in the lobby who hasn't readied up yet. This is useful for visualizing who is holding up the lobby. Check the wiki for details.
 - Elytra are now supported chest pieces in class chests.
 - Boss names now support color codes.
+- The Root Target ability now uses potion effects (slowness, slow falling, and negative jump boost) instead of repeated teleports. This should make for a smoother root experience.
 - Config-files with missing `pet-items` nodes no longer errors. A missing `pet-items` node in `global-settings` is treated as empty, i.e. no pet items will be registered.
 
 ## [0.104.2] - 2020-01-03

src/main/java/com/garbagemule/MobArena/waves/ability/core/RootTarget.java

@@ -1,16 +1,14 @@
 package com.garbagemule.MobArena.waves.ability.core;
 
 import com.garbagemule.MobArena.framework.Arena;
-import com.garbagemule.MobArena.region.ArenaRegion;
 import com.garbagemule.MobArena.waves.MABoss;
 import com.garbagemule.MobArena.waves.ability.Ability;
 import com.garbagemule.MobArena.waves.ability.AbilityInfo;
 import com.garbagemule.MobArena.waves.ability.AbilityUtils;
-import org.bukkit.Location;
-import org.bukkit.block.Block;
-import org.bukkit.block.BlockFace;
 import org.bukkit.entity.LivingEntity;
 import org.bukkit.entity.Player;
+import org.bukkit.potion.PotionEffect;
+import org.bukkit.potion.PotionEffectType;
 
 /**
  * DISCLAIMER: The Ability source code is provided as-is, and the creator(s) of
@@ -36,16 +34,14 @@ import org.bukkit.entity.Player;
 public class RootTarget implements Ability
 {
     /**
-     * How many times the player will be warped back to his original position.
-     * Must be greater than 0.
+     * How long the the potions last (in ticks).
      */
-    private static final int ITERATIONS = 30;
+    private static final int DURATION = 30;
     
     /**
-     * How many server ticks between each iteration of
-     * Must be greater than 0.
+     * The amplifier for the potions.
      */
-    private static final int TICKS = 1;
+    private static final int AMPLIFIER = 100;
     
     @Override
     public void execute(Arena arena, MABoss boss) {
@@ -54,49 +50,8 @@ public class RootTarget implements Ability
             return;
 
         Player player = (Player) target;
-        ArenaRegion region = arena.getRegion();
-
-        Block block = player.getLocation().getBlock();
-        Block solid = findSolidBlockBelow(region, block);
-
-        Location location = player.getLocation();
-        location.setY(solid.getLocation().getY() + 1);
-
-        rootTarget(arena, player, location, ITERATIONS);
-    }
-
-    private Block findSolidBlockBelow(ArenaRegion region, Block block) {
-        Block below = block.getRelative(BlockFace.DOWN);
-
-        // If the block below is not in the region, return the block itself
-        if (!region.contains(below.getLocation())) {
-            return block;
-        }
-
-        // If the block below is solid, return it
-        if (below.getType().isSolid()) {
-            return below;
-        }
-
-        // Otherwise, recurse downwards
-        return findSolidBlockBelow(region, below);
-    }
-    
-    private void rootTarget(final Arena arena, final Player p, final Location loc, final int counter) {
-        // If the counter is 0, we're done.
-        if (counter <= 0) {
-            return;
-        }
-        
-        arena.scheduleTask(new Runnable() {
-            public void run() {
-                if (!arena.isRunning() || !arena.inArena(p)) {
-                    return;
-                }
-                
-                p.teleport(loc);
-                rootTarget(arena, p, loc, counter - 1);
-            }
-        }, TICKS);
+        player.addPotionEffect(new PotionEffect(PotionEffectType.SLOW, DURATION, AMPLIFIER));
+        player.addPotionEffect(new PotionEffect(PotionEffectType.SLOW_FALLING, DURATION, AMPLIFIER));
+        player.addPotionEffect(new PotionEffect(PotionEffectType.JUMP, DURATION, -AMPLIFIER));
     }
 }