Amphibious mobs :O

src/main/java/fathertoast/specialmobs/client/ClientRegister.java

@@ -3,15 +3,13 @@ package fathertoast.specialmobs.client;
 import fathertoast.specialmobs.client.renderer.entity.family.*;
 import fathertoast.specialmobs.client.renderer.entity.projectile.BugSpitRenderer;
 import fathertoast.specialmobs.client.renderer.entity.projectile.SpecialFishingBobberRenderer;
-import fathertoast.specialmobs.client.renderer.entity.species.CorporealShiftGhastRenderer;
-import fathertoast.specialmobs.client.renderer.entity.species.NinjaSkeletonRenderer;
-import fathertoast.specialmobs.client.renderer.entity.species.PotionSlimeRenderer;
-import fathertoast.specialmobs.client.renderer.entity.species.SpecialZombieVillagerRenderer;
+import fathertoast.specialmobs.client.renderer.entity.species.*;
 import fathertoast.specialmobs.common.bestiary.MobFamily;
 import fathertoast.specialmobs.common.config.Config;
 import fathertoast.specialmobs.common.core.SpecialMobs;
 import fathertoast.specialmobs.common.core.register.SMEntities;
 import fathertoast.specialmobs.common.entity.ghast.CorporealShiftGhastEntity;
+import fathertoast.specialmobs.common.entity.silverfish.PufferSilverfishEntity;
 import fathertoast.specialmobs.common.entity.skeleton.NinjaSkeletonEntity;
 import fathertoast.specialmobs.common.entity.slime.PotionSlimeEntity;
 import fathertoast.specialmobs.common.entity.witherskeleton.NinjaWitherSkeletonEntity;
@@ -77,6 +75,8 @@ public class ClientRegister {
         
         registerSpeciesRenderer( PotionSlimeEntity.SPECIES, PotionSlimeRenderer::new );
         
+        registerSpeciesRenderer( PufferSilverfishEntity.SPECIES, ShortSilverfishRenderer::new );
+        
         registerSpeciesRenderer( CorporealShiftGhastEntity.SPECIES, CorporealShiftGhastRenderer::new );
         
         // Other

src/main/java/fathertoast/specialmobs/client/renderer/entity/species/ShortSilverfishRenderer.java

@@ -0,0 +1,27 @@
+package fathertoast.specialmobs.client.renderer.entity.species;
+
+import fathertoast.specialmobs.client.renderer.entity.family.SpecialSilverfishRenderer;
+import net.minecraft.client.renderer.entity.EntityRendererManager;
+import net.minecraft.entity.monster.SilverfishEntity;
+import net.minecraft.util.math.MathHelper;
+import net.minecraft.util.math.vector.Vector3d;
+import net.minecraftforge.api.distmarker.Dist;
+import net.minecraftforge.api.distmarker.OnlyIn;
+
+@OnlyIn( Dist.CLIENT )
+public class ShortSilverfishRenderer extends SpecialSilverfishRenderer {
+    
+    private static final float FORWARD_OFFSET = 0.4F;
+    
+    public ShortSilverfishRenderer( EntityRendererManager rendererManager ) {
+        super( rendererManager );
+    }
+    
+    @Override
+    public Vector3d getRenderOffset( SilverfishEntity entity, float partialTicks ) {
+        final float angle = MathHelper.lerp( partialTicks, entity.yRotO, entity.yRot ) * (float) Math.PI / 180.0F;
+        final float forwardX = -MathHelper.sin( angle );
+        final float forwardZ = MathHelper.cos( angle );
+        return new Vector3d( forwardX * FORWARD_OFFSET, 0.0, forwardZ * FORWARD_OFFSET );
+    }
+}

src/main/java/fathertoast/specialmobs/common/bestiary/MobFamily.java

@@ -86,7 +86,7 @@ public class MobFamily<T extends LivingEntity, V extends FamilyConfig> {
     public static final MobFamily<SilverfishEntity, SilverfishFamilyConfig> SILVERFISH = new MobFamily<>( SilverfishFamilyConfig::new,
             "Silverfish", "silverfish", 0x6E6E6E, new EntityType[] { EntityType.SILVERFISH },
             "Albino", "Blinding", "Desiccated", "Fire", "Fishing", "Flying", "Poison", "Puffer", "Tough"
-    );//TODO puffer
+    );
     
     public static final MobFamily<EndermanEntity, FamilyConfig> ENDERMAN = new MobFamily<>( FamilyConfig::new,
             "Enderman", "endermen", 0x161616, new EntityType[] { EntityType.ENDERMAN },

src/main/java/fathertoast/specialmobs/common/core/SpecialMobs.java

@@ -82,7 +82,6 @@ public class SpecialMobs {
      *          + natural spawning
      *      - silverfish
      *          - ranged attack AI (spitter)
-     *          + puffer
      *      - endermen
      *      - witches
      *          - ability to equip held items (wonky)

src/main/java/fathertoast/specialmobs/common/entity/ai/AmphibiousMovementController.java

@@ -0,0 +1,57 @@
+package fathertoast.specialmobs.common.entity.ai;
+
+import net.minecraft.entity.LivingEntity;
+import net.minecraft.entity.MobEntity;
+import net.minecraft.entity.ai.attributes.Attributes;
+import net.minecraft.entity.ai.controller.MovementController;
+import net.minecraft.util.math.MathHelper;
+
+/**
+ * The drowned movement controller repurposed for use on other mobs.
+ * <p>
+ * {@link net.minecraft.entity.monster.DrownedEntity.MoveHelperController}
+ */
+public class AmphibiousMovementController<T extends MobEntity & IAmphibiousMob> extends MovementController {
+    
+    private final T owner;
+    
+    public AmphibiousMovementController( T entity ) {
+        super( entity );
+        owner = entity;
+    }
+    
+    public void tick() {
+        final LivingEntity target = owner.getTarget();
+        if( owner.shouldSwim() && owner.isInWater() ) {
+            if( target != null && target.getY() > owner.getY() || owner.isSwimmingUp() ) {
+                owner.setDeltaMovement( owner.getDeltaMovement().add( 0.0, 0.002, 0.0 ) );
+            }
+            
+            if( operation != MovementController.Action.MOVE_TO || owner.getNavigation().isDone() ) {
+                owner.setSpeed( 0.0F );
+                return;
+            }
+            
+            final double dX = wantedX - owner.getX();
+            final double dY = wantedY - owner.getY();
+            final double dZ = wantedZ - owner.getZ();
+            final double distance = MathHelper.sqrt( dX * dX + dY * dY + dZ * dZ );
+            
+            final float targetYRot = (float) MathHelper.atan2( dZ, dX ) * 180.0F / (float) Math.PI - 90.0F;
+            owner.yRot = rotlerp( owner.yRot, targetYRot, 90.0F );
+            owner.yBodyRot = owner.yRot;
+            
+            final float maxSpeed = (float) (speedModifier * owner.getAttributeValue( Attributes.MOVEMENT_SPEED ));
+            final float speed = MathHelper.lerp( 0.125F, owner.getSpeed(), maxSpeed );
+            owner.setSpeed( speed );
+            owner.setDeltaMovement( owner.getDeltaMovement().add(
+                    speed * dX * 0.005, speed * dY / distance * 0.1, speed * dZ * 0.005 ) );
+        }
+        else {
+            if( !owner.isOnGround() ) {
+                owner.setDeltaMovement( owner.getDeltaMovement().add( 0.0, -0.008, 0.0 ) );
+            }
+            super.tick();
+        }
+    }
+}

src/main/java/fathertoast/specialmobs/common/entity/ai/IAmphibiousMob.java

@@ -0,0 +1,21 @@
+package fathertoast.specialmobs.common.entity.ai;
+
+/**
+ * Monsters must implement this interface to use the amphibious AI.
+ */
+public interface IAmphibiousMob {
+    /** @return True if this mob should use its swimming navigator for its current goal. */
+    default boolean shouldSwim() { return isSwimmingUp(); }
+    
+    /** Sets whether this mob should swim upward. */
+    void setSwimmingUp( boolean value );
+    
+    /** @return True if this mob should swim upward. */
+    boolean isSwimmingUp();
+    
+    /** Sets this mob's current navigator to swimming mode. */
+    void setNavigatorToSwim();
+    
+    /** Sets this mob's current navigator to ground mode. */
+    void setNavigatorToGround();
+}

src/main/java/fathertoast/specialmobs/common/entity/ai/goal/AmphibiousGoToShoreGoal.java

@@ -0,0 +1,51 @@
+package fathertoast.specialmobs.common.entity.ai.goal;
+
+import fathertoast.specialmobs.common.entity.ai.IAmphibiousMob;
+import net.minecraft.entity.CreatureEntity;
+import net.minecraft.entity.ai.goal.MoveToBlockGoal;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.world.IWorldReader;
+
+/**
+ * The drowned "go to beach" goal repurposed for use on other mobs.
+ * <p>
+ * {@link net.minecraft.entity.monster.DrownedEntity.GoToBeachGoal}
+ */
+public class AmphibiousGoToShoreGoal<T extends CreatureEntity & IAmphibiousMob> extends MoveToBlockGoal {
+    
+    private final T amphibiousMob;
+    
+    private boolean disableAtDay = true;
+    
+    public AmphibiousGoToShoreGoal( T entity, double speed ) {
+        super( entity, speed, 8, 2 );
+        amphibiousMob = entity;
+    }
+    
+    /** Builder that allows this goal to run during the day. */
+    public AmphibiousGoToShoreGoal<T> alwaysEnabled() {
+        disableAtDay = false;
+        return this;
+    }
+    
+    /** @return Returns true if this AI can be activated. */
+    @Override
+    public boolean canUse() {
+        return super.canUse() && !(disableAtDay && mob.level.isDay()) && mob.isInWater() && mob.getY() >= mob.level.getSeaLevel() - 3;
+    }
+    
+    /** @return True if the position is valid to move to. */
+    @Override
+    protected boolean isValidTarget( IWorldReader world, BlockPos targetPos ) {
+        return world.isEmptyBlock( targetPos.above() ) && world.isEmptyBlock( targetPos.above( 2 ) ) &&
+                world.getBlockState( targetPos ).entityCanStandOn( world, targetPos, mob );
+    }
+    
+    /** Called when this AI is activated. */
+    @Override
+    public void start() {
+        amphibiousMob.setSwimmingUp( false );
+        amphibiousMob.setNavigatorToGround();
+        super.start();
+    }
+}

src/main/java/fathertoast/specialmobs/common/entity/ai/goal/AmphibiousGoToWaterGoal.java

@@ -0,0 +1,81 @@
+package fathertoast.specialmobs.common.entity.ai.goal;
+
+import fathertoast.specialmobs.common.entity.ai.IAmphibiousMob;
+import net.minecraft.block.Blocks;
+import net.minecraft.entity.MobEntity;
+import net.minecraft.entity.ai.goal.Goal;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.math.vector.Vector3d;
+
+import javax.annotation.Nullable;
+import java.util.EnumSet;
+import java.util.Random;
+
+/**
+ * The drowned "go to water" goal repurposed for use on other mobs.
+ * <p>
+ * {@link net.minecraft.entity.monster.DrownedEntity.GoToWaterGoal}
+ */
+public class AmphibiousGoToWaterGoal<T extends MobEntity & IAmphibiousMob> extends Goal {
+    
+    private final T mob;
+    private final double speedModifier;
+    
+    private boolean disableAtNight = true;
+    
+    private double wantedX;
+    private double wantedY;
+    private double wantedZ;
+    
+    public AmphibiousGoToWaterGoal( T entity, double speed ) {
+        mob = entity;
+        speedModifier = speed;
+        setFlags( EnumSet.of( Goal.Flag.MOVE ) );
+    }
+    
+    /** Builder that allows this goal to run during the night. */
+    public AmphibiousGoToWaterGoal<T> alwaysEnabled() {
+        disableAtNight = false;
+        return this;
+    }
+    
+    /** @return Returns true if this AI can be activated. */
+    @Override
+    public boolean canUse() {
+        if( disableAtNight && !mob.level.isDay() || mob.isInWater() ) return false;
+        
+        final Vector3d targetPos = findWaterPos();
+        if( targetPos == null ) return false;
+        
+        wantedX = targetPos.x;
+        wantedY = targetPos.y;
+        wantedZ = targetPos.z;
+        return true;
+    }
+    
+    /** @return Called each update while active and returns true if this AI can remain active. */
+    @Override
+    public boolean canContinueToUse() { return !mob.getNavigation().isDone(); }
+    
+    /** Called when this AI is activated. */
+    @Override
+    public void start() { mob.getNavigation().moveTo( wantedX, wantedY, wantedZ, speedModifier ); }
+    
+    /** @return A random nearby position of water, or null if none is found after a few tries. */
+    @Nullable
+    private Vector3d findWaterPos() {
+        final Random random = mob.getRandom();
+        final BlockPos origin = mob.blockPosition();
+        
+        for( int i = 0; i < 10; i++ ) {
+            final BlockPos target = origin.offset(
+                    random.nextInt( 20 ) - 10,
+                    2 - random.nextInt( 8 ),
+                    random.nextInt( 20 ) - 10 );
+            if( mob.level.getBlockState( target ).is( Blocks.WATER ) ) {
+                return Vector3d.atBottomCenterOf( target );
+            }
+        }
+        return null;
+    }
+}

src/main/java/fathertoast/specialmobs/common/entity/ai/goal/AmphibiousMeleeAttackGoal.java

@@ -0,0 +1,47 @@
+package fathertoast.specialmobs.common.entity.ai.goal;
+
+import fathertoast.specialmobs.common.entity.ai.IAmphibiousMob;
+import net.minecraft.entity.CreatureEntity;
+import net.minecraft.entity.LivingEntity;
+import net.minecraft.entity.ai.goal.MeleeAttackGoal;
+
+import javax.annotation.Nullable;
+
+/**
+ * The drowned "attack" goal repurposed for use on other mobs.
+ * Prevents mobs from attacking targets outside of water during the day.
+ * <p>
+ * {@link net.minecraft.entity.monster.DrownedEntity.AttackGoal}
+ */
+public class AmphibiousMeleeAttackGoal<T extends CreatureEntity & IAmphibiousMob> extends MeleeAttackGoal {
+    
+    /** @return True if the target is valid. */
+    public static boolean isValidTarget( @Nullable LivingEntity target ) {
+        return target != null && (!target.level.isDay() || target.isInWater());
+    }
+    
+    public AmphibiousMeleeAttackGoal( T entity, double speed, boolean longMemory ) { super( entity, speed, longMemory ); }
+    
+    /** @return Returns true if this AI can be activated. */
+    @Override
+    public boolean canUse() { return super.canUse() && isValidTarget( mob.getTarget() ); }
+    
+    /** @return Called each update while active and returns true if this AI can remain active. */
+    @Override
+    public boolean canContinueToUse() { return super.canContinueToUse() && isValidTarget( mob.getTarget() ); }
+    
+    // Uncomment if ever needed
+    //    /** A zombie attack version of the normal amphibious melee goal. */
+    //    public static class Zombie<T extends ZombieEntity & IAmphibiousMob> extends ZombieAttackGoal {
+    //
+    //        public Zombie( T entity, double speed, boolean longMemory ) { super( entity, speed, longMemory ); }
+    //
+    //        /** @return Returns true if this AI can be activated. */
+    //        @Override
+    //        public boolean canUse() { return super.canUse() && isValidTarget( mob.getTarget() ); }
+    //
+    //        /** @return Called each update while active and returns true if this AI can remain active. */
+    //        @Override
+    //        public boolean canContinueToUse() { return super.canContinueToUse() && isValidTarget( mob.getTarget() ); }
+    //    }
+}

src/main/java/fathertoast/specialmobs/common/entity/ai/goal/AmphibiousSwimUpGoal.java

@@ -0,0 +1,82 @@
+package fathertoast.specialmobs.common.entity.ai.goal;
+
+import fathertoast.specialmobs.common.entity.ai.IAmphibiousMob;
+import net.minecraft.entity.CreatureEntity;
+import net.minecraft.entity.ai.RandomPositionGenerator;
+import net.minecraft.entity.ai.goal.Goal;
+import net.minecraft.pathfinding.Path;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.math.vector.Vector3d;
+
+/**
+ * The drowned "swim up" goal repurposed for use on other mobs.
+ * <p>
+ * {@link net.minecraft.entity.monster.DrownedEntity.SwimUpGoal}
+ */
+public class AmphibiousSwimUpGoal<T extends CreatureEntity & IAmphibiousMob> extends Goal {
+    
+    private final T mob;
+    private final double speedModifier;
+    private final int seaLevel;
+    
+    private boolean disableAtDay = true;
+    
+    private boolean stuck;
+    
+    public AmphibiousSwimUpGoal( T entity, double speed ) {
+        mob = entity;
+        speedModifier = speed;
+        seaLevel = entity.level.getSeaLevel() - 1;
+    }
+    
+    /** Builder that allows this goal to run during the day. */
+    public AmphibiousSwimUpGoal<T> alwaysEnabled() {
+        disableAtDay = false;
+        return this;
+    }
+    
+    /** @return Returns true if this AI can be activated. */
+    @Override
+    public boolean canUse() { return !(disableAtDay && mob.level.isDay()) && mob.isInWater() && mob.getY() < seaLevel - 1; }
+    
+    /** @return Called each update while active and returns true if this AI can remain active. */
+    @Override
+    public boolean canContinueToUse() { return canUse() && !stuck; }
+    
+    /** Called when this AI is activated. */
+    @Override
+    public void start() {
+        mob.setSwimmingUp( true );
+        stuck = false;
+    }
+    
+    /** Called when this AI is deactivated. */
+    @Override
+    public void stop() { mob.setSwimmingUp( false ); }
+    
+    /** Called each tick while this AI is active. */
+    @Override
+    public void tick() {
+        if( mob.getY() < seaLevel && (mob.getNavigation().isDone() || closeToNextPos()) ) {
+            final Vector3d pos = RandomPositionGenerator.getPosTowards( mob, 4, 8,
+                    new Vector3d( mob.getX(), seaLevel, mob.getZ() ) );
+            if( pos == null ) {
+                stuck = true;
+                return;
+            }
+            
+            mob.getNavigation().moveTo( pos.x, pos.y, pos.z, speedModifier );
+        }
+        
+    }
+    
+    /** @return True if the entity is within 2 blocks of its pathing target. */
+    private boolean closeToNextPos() {
+        final Path path = mob.getNavigation().getPath();
+        if( path != null ) {
+            final BlockPos pos = path.getTarget();
+            return mob.distanceToSqr( pos.getX() + 0.5, pos.getY(), pos.getZ() + 0.5 ) < 4.0;
+        }
+        return false;
+    }
+}

src/main/java/fathertoast/specialmobs/common/entity/creeper/DrowningCreeperEntity.java

@@ -3,6 +3,11 @@ package fathertoast.specialmobs.common.entity.creeper;
 import fathertoast.specialmobs.common.bestiary.BestiaryInfo;
 import fathertoast.specialmobs.common.bestiary.MobFamily;
 import fathertoast.specialmobs.common.bestiary.SpecialMob;
+import fathertoast.specialmobs.common.entity.ai.AIHelper;
+import fathertoast.specialmobs.common.entity.ai.AmphibiousMovementController;
+import fathertoast.specialmobs.common.entity.ai.IAmphibiousMob;
+import fathertoast.specialmobs.common.entity.ai.goal.AmphibiousGoToWaterGoal;
+import fathertoast.specialmobs.common.entity.ai.goal.AmphibiousSwimUpGoal;
 import fathertoast.specialmobs.common.util.ExplosionHelper;
 import fathertoast.specialmobs.common.util.References;
 import fathertoast.specialmobs.datagen.loot.LootEntryItemBuilder;
@@ -11,18 +16,26 @@ import fathertoast.specialmobs.datagen.loot.LootTableBuilder;
 import net.minecraft.block.BlockState;
 import net.minecraft.block.Blocks;
 import net.minecraft.entity.EntityType;
+import net.minecraft.entity.LivingEntity;
+import net.minecraft.entity.MoverType;
 import net.minecraft.entity.ai.attributes.Attributes;
+import net.minecraft.entity.ai.goal.SwimGoal;
 import net.minecraft.entity.passive.fish.PufferfishEntity;
 import net.minecraft.item.Items;
+import net.minecraft.nbt.CompoundNBT;
+import net.minecraft.pathfinding.GroundPathNavigator;
+import net.minecraft.pathfinding.PathNodeType;
+import net.minecraft.pathfinding.SwimmerPathNavigator;
 import net.minecraft.state.properties.BlockStateProperties;
 import net.minecraft.tags.BlockTags;
 import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.math.vector.Vector3d;
 import net.minecraft.world.Explosion;
 import net.minecraft.world.IServerWorld;
 import net.minecraft.world.World;
 
 @SpecialMob
-public class DrowningCreeperEntity extends _SpecialCreeperEntity {
+public class DrowningCreeperEntity extends _SpecialCreeperEntity implements IAmphibiousMob {
     
     //--------------- Static Special Mob Hooks ----------------
     
@@ -66,7 +79,23 @@ public class DrowningCreeperEntity extends _SpecialCreeperEntity {
     
     //--------------- Variant-Specific Implementations ----------------
     
-    public DrowningCreeperEntity( EntityType<? extends _SpecialCreeperEntity> entityType, World world ) { super( entityType, world ); }
+    public DrowningCreeperEntity( EntityType<? extends _SpecialCreeperEntity> entityType, World world ) {
+        super( entityType, world );
+        moveControl = new AmphibiousMovementController<>( this );
+        waterNavigation = new SwimmerPathNavigator( this, world );
+        groundNavigation = new GroundPathNavigator( this, world );
+        maxUpStep = 1.0F;
+        setPathfindingMalus( PathNodeType.WATER, PathNodeType.WALKABLE.getMalus() );
+    }
+    
+    /** Override to change this entity's AI goals. */
+    @Override
+    protected void registerVariantGoals() {
+        AIHelper.removeGoals( goalSelector, SwimGoal.class );
+        AIHelper.insertGoal( goalSelector, 5, new AmphibiousGoToWaterGoal<>( this, 1.0 ).alwaysEnabled() );
+        AIHelper.insertGoal( goalSelector, 6, new AmphibiousSwimUpGoal<>( this, 1.0 ) );
+        AIHelper.replaceWaterAvoidingRandomWalking( this, 0.8 );
+    }
     
     /** Override to change this creeper's explosion power multiplier. */
     @Override
@@ -92,7 +121,7 @@ public class DrowningCreeperEntity extends _SpecialCreeperEntity {
         final int rMinusOneSq = (radius - 1) * (radius - 1);
         final BlockPos center = new BlockPos( explosion.getPos() );
         
-        // Track how many pufferfish have been spawned
+        // Track how many pufferfish have been spawned so we don't spawn a bunch of them
         spawnPufferfish( center.above( 1 ) );
         int pufferCount = 1;
         
@@ -123,8 +152,7 @@ public class DrowningCreeperEntity extends _SpecialCreeperEntity {
                                     // Water fill
                                     level.setBlock( pos, water, References.SetBlockFlags.DEFAULTS );
                                     
-                                    // Prevent greater radiuses from spawning a bazillion pufferfish
-                                    if( random.nextFloat() < 0.01F && pufferCount < 10 ) {
+                                    if( random.nextFloat() < 0.0075F && pufferCount < 5 ) {
                                         spawnPufferfish( pos );
                                         pufferCount++;
                                     }
@@ -153,4 +181,72 @@ public class DrowningCreeperEntity extends _SpecialCreeperEntity {
     
     @Override
     public boolean isInWaterRainOrBubble() { return true; }
+    
+    /** Override to load data from this entity's NBT data. */
+    @Override
+    public void readVariantSaveData( CompoundNBT saveTag ) {
+        setPathfindingMalus( PathNodeType.WATER, PathNodeType.WALKABLE.getMalus() );
+    }
+    
+    
+    //--------------- IAmphibiousMob Implementation ----------------
+    
+    private final SwimmerPathNavigator waterNavigation;
+    private final GroundPathNavigator groundNavigation;
+    
+    private boolean swimmingUp;
+    
+    /** Called each tick to update this entity's swimming state. */
+    @Override
+    public void updateSwimming() {
+        if( !level.isClientSide ) {
+            if( isEffectiveAi() && isUnderWater() && shouldSwim() ) {
+                setNavigatorToSwim();
+                setSwimming( true );
+            }
+            else {
+                setNavigatorToGround();
+                setSwimming( false );
+            }
+        }
+    }
+    
+    /** Moves this entity in the desired direction. Input magnitude of < 1 scales down movement speed. */
+    @Override
+    public void travel( Vector3d input ) {
+        if( isEffectiveAi() && isUnderWater() && shouldSwim() ) {
+            moveRelative( 0.01F, input );
+            move( MoverType.SELF, getDeltaMovement() );
+            setDeltaMovement( getDeltaMovement().scale( 0.9 ) );
+        }
+        else super.travel( input );
+    }
+    
+    /** @return Water drag coefficient. */
+    @Override
+    protected float getWaterSlowDown() { return 0.9F; }
+    
+    /** @return True if this mob should use its swimming navigator for its current goal. */
+    @Override
+    public boolean shouldSwim() {
+        if( swimmingUp ) return true;
+        final LivingEntity target = getTarget();
+        return target != null && target.isInWater();
+    }
+    
+    /** Sets whether this mob should swim upward. */
+    @Override
+    public void setSwimmingUp( boolean value ) { swimmingUp = value; }
+    
+    /** @return True if this mob should swim upward. */
+    @Override
+    public boolean isSwimmingUp() { return swimmingUp; }
+    
+    /** Sets this mob's current navigator to swimming mode. */
+    @Override
+    public void setNavigatorToSwim() { navigation = waterNavigation; }
+    
+    /** Sets this mob's current navigator to ground mode. */
+    @Override
+    public void setNavigatorToGround() { navigation = groundNavigation; }
 }

src/main/java/fathertoast/specialmobs/common/entity/drowned/_SpecialDrownedEntity.java

@@ -131,6 +131,8 @@ public class _SpecialDrownedEntity extends DrownedEntity implements ISpecialMob<
     /** The parameter for special mob render scale. */
     private static final DataParameter<Float> SCALE = EntityDataManager.defineId( _SpecialDrownedEntity.class, DataSerializers.FLOAT );
     
+    private boolean needsToBeDeeper;
+    
     public _SpecialDrownedEntity( EntityType<? extends _SpecialDrownedEntity> entityType, World world ) {
         super( entityType, world );
         recalculateAttackGoal();
@@ -172,6 +174,35 @@ public class _SpecialDrownedEntity extends DrownedEntity implements ISpecialMob<
         level.addFreshEntity( trident );
     }
     
+    /** Called each tick to update this entity's swimming state. */
+    @Override
+    public void updateSwimming() {
+        if( !level.isClientSide && isEffectiveAi() ) needsToBeDeeper = true;
+        super.updateSwimming();
+    }
+    
+    /** Moves this entity in the desired direction. Input magnitude of < 1 scales down movement speed. */
+    @Override
+    public void travel( Vector3d input ) {
+        if( isEffectiveAi() ) needsToBeDeeper = true;
+        super.travel( input );
+    }
+    
+    /** @return Water drag coefficient. */
+    @Override
+    protected float getWaterSlowDown() { return 0.9F; } // Improve mobility in shallow water
+    
+    /** @return True if this entity is in water. */
+    @Override
+    public boolean isInWater() {
+        // Hacky way to fix vanilla drowned AI breaking in shallow water
+        if( needsToBeDeeper ) {
+            needsToBeDeeper = false;
+            return isUnderWater();
+        }
+        return super.isInWater();
+    }
+    
     
     //--------------- ISpecialMob Implementation ----------------
     

src/main/java/fathertoast/specialmobs/common/entity/silverfish/AmphibiousSilverfishEntity.java

@@ -0,0 +1,97 @@
+package fathertoast.specialmobs.common.entity.silverfish;
+
+import fathertoast.specialmobs.common.entity.ai.AmphibiousMovementController;
+import fathertoast.specialmobs.common.entity.ai.IAmphibiousMob;
+import net.minecraft.entity.EntityType;
+import net.minecraft.entity.LivingEntity;
+import net.minecraft.entity.MoverType;
+import net.minecraft.nbt.CompoundNBT;
+import net.minecraft.pathfinding.GroundPathNavigator;
+import net.minecraft.pathfinding.PathNodeType;
+import net.minecraft.pathfinding.SwimmerPathNavigator;
+import net.minecraft.util.math.vector.Vector3d;
+import net.minecraft.world.World;
+
+/**
+ * A bare-bones implementation of an amphibious silverfish. Just fix the AI and it's good to go.
+ */
+public abstract class AmphibiousSilverfishEntity extends _SpecialSilverfishEntity implements IAmphibiousMob {
+    
+    private final SwimmerPathNavigator waterNavigation;
+    private final GroundPathNavigator groundNavigation;
+    
+    private boolean swimmingUp;
+    
+    public AmphibiousSilverfishEntity( EntityType<? extends _SpecialSilverfishEntity> entityType, World world ) {
+        super( entityType, world );
+        moveControl = new AmphibiousMovementController<>( this );
+        waterNavigation = new SwimmerPathNavigator( this, world );
+        groundNavigation = new GroundPathNavigator( this, world );
+        maxUpStep = 1.0F;
+        setPathfindingMalus( PathNodeType.WATER, PathNodeType.WALKABLE.getMalus() );
+    }
+    
+    /** Loads data from this entity's base NBT compound that is specific to its subclass. */
+    @Override
+    public void readAdditionalSaveData( CompoundNBT tag ) {
+        super.readAdditionalSaveData( tag );
+        setPathfindingMalus( PathNodeType.WATER, PathNodeType.WALKABLE.getMalus() );
+    }
+    
+    
+    //--------------- IAmphibiousMob Implementation ----------------
+    
+    /** Called each tick to update this entity's swimming state. */
+    @Override
+    public void updateSwimming() {
+        if( !level.isClientSide ) {
+            if( isEffectiveAi() && isUnderWater() && shouldSwim() ) {
+                setNavigatorToSwim();
+                setSwimming( true );
+            }
+            else {
+                setNavigatorToGround();
+                setSwimming( false );
+            }
+        }
+    }
+    
+    /** Moves this entity in the desired direction. Input magnitude of < 1 scales down movement speed. */
+    @Override
+    public void travel( Vector3d input ) {
+        if( isEffectiveAi() && isUnderWater() && shouldSwim() ) {
+            moveRelative( 0.01F, input );
+            move( MoverType.SELF, getDeltaMovement() );
+            setDeltaMovement( getDeltaMovement().scale( 0.9 ) );
+        }
+        else super.travel( input );
+    }
+    
+    /** @return Water drag coefficient. */
+    @Override
+    protected float getWaterSlowDown() { return 0.9F; }
+    
+    /** @return True if this mob should use its swimming navigator for its current goal. */
+    @Override
+    public boolean shouldSwim() {
+        if( swimmingUp ) return true;
+        final LivingEntity target = getTarget();
+        return target != null && target.isInWater();
+    }
+    
+    /** Sets whether this mob should swim upward. */
+    @Override
+    public void setSwimmingUp( boolean value ) { swimmingUp = value; }
+    
+    /** @return True if this mob should swim upward. */
+    @Override
+    public boolean isSwimmingUp() { return swimmingUp; }
+    
+    /** Sets this mob's current navigator to swimming mode. */
+    @Override
+    public void setNavigatorToSwim() { navigation = waterNavigation; }
+    
+    /** Sets this mob's current navigator to ground mode. */
+    @Override
+    public void setNavigatorToGround() { navigation = groundNavigation; }
+}

src/main/java/fathertoast/specialmobs/common/entity/silverfish/FishingSilverfishEntity.java

@@ -7,6 +7,8 @@ import fathertoast.specialmobs.common.config.species.SilverfishSpeciesConfig;
 import fathertoast.specialmobs.common.config.species.SpeciesConfig;
 import fathertoast.specialmobs.common.entity.ai.AIHelper;
 import fathertoast.specialmobs.common.entity.ai.IAngler;
+import fathertoast.specialmobs.common.entity.ai.goal.AmphibiousGoToShoreGoal;
+import fathertoast.specialmobs.common.entity.ai.goal.AmphibiousSwimUpGoal;
 import fathertoast.specialmobs.common.entity.ai.goal.AnglerGoal;
 import fathertoast.specialmobs.common.entity.ai.goal.PassiveRangedAttackGoal;
 import fathertoast.specialmobs.common.util.References;
@@ -15,11 +17,12 @@ import fathertoast.specialmobs.datagen.loot.LootPoolBuilder;
 import fathertoast.specialmobs.datagen.loot.LootTableBuilder;
 import net.minecraft.entity.EntityType;
 import net.minecraft.entity.ai.attributes.Attributes;
+import net.minecraft.entity.ai.goal.SwimGoal;
 import net.minecraft.item.Items;
 import net.minecraft.world.World;
 
 @SpecialMob
-public class FishingSilverfishEntity extends _SpecialSilverfishEntity implements IAngler {
+public class FishingSilverfishEntity extends AmphibiousSilverfishEntity implements IAngler {
     
     //--------------- Static Special Mob Hooks ----------------
     
@@ -77,6 +80,10 @@ public class FishingSilverfishEntity extends _SpecialSilverfishEntity implements
     protected void registerVariantGoals() {
         AIHelper.removeGoals( goalSelector, PassiveRangedAttackGoal.class ); // Disable spit attack use
         goalSelector.addGoal( 4, new AnglerGoal<>( this ) );
+        
+        AIHelper.removeGoals( goalSelector, SwimGoal.class );
+        AIHelper.insertGoal( goalSelector, 5, new AmphibiousGoToShoreGoal<>( this, 1.0 ).alwaysEnabled() );
+        AIHelper.insertGoal( goalSelector, 6, new AmphibiousSwimUpGoal<>( this, 1.0 ).alwaysEnabled() );
     }
     
     

src/main/java/fathertoast/specialmobs/common/entity/silverfish/PufferSilverfishEntity.java

@@ -4,16 +4,19 @@ import fathertoast.specialmobs.common.bestiary.BestiaryInfo;
 import fathertoast.specialmobs.common.bestiary.MobFamily;
 import fathertoast.specialmobs.common.bestiary.SpecialMob;
 import fathertoast.specialmobs.common.entity.MobHelper;
+import fathertoast.specialmobs.common.entity.ai.AIHelper;
+import fathertoast.specialmobs.common.entity.ai.goal.AmphibiousGoToWaterGoal;
 import fathertoast.specialmobs.common.util.References;
 import fathertoast.specialmobs.datagen.loot.LootTableBuilder;
 import net.minecraft.entity.EntityType;
 import net.minecraft.entity.LivingEntity;
+import net.minecraft.entity.ai.goal.SwimGoal;
 import net.minecraft.item.Items;
 import net.minecraft.potion.Effects;
 import net.minecraft.world.World;
 
 @SpecialMob
-public class PufferSilverfishEntity extends _SpecialSilverfishEntity {
+public class PufferSilverfishEntity extends AmphibiousSilverfishEntity {
     
     //--------------- Static Special Mob Hooks ----------------
     
@@ -23,7 +26,7 @@ public class PufferSilverfishEntity extends _SpecialSilverfishEntity {
     @SpecialMob.BestiaryInfoSupplier
     public static void getBestiaryInfo( BestiaryInfo.Builder bestiaryInfo ) {
         bestiaryInfo.color( 0xE6E861 ).theme( BestiaryInfo.Theme.WATER )
-                .uniqueTextureBaseOnly()//TODO Change texture or renderer to fix offset
+                .uniqueTextureBaseOnly()
                 .addExperience( 1 ).drownImmune().effectImmune( Effects.POISON );
     }
     
@@ -52,7 +55,12 @@ public class PufferSilverfishEntity extends _SpecialSilverfishEntity {
     
     public PufferSilverfishEntity( EntityType<? extends _SpecialSilverfishEntity> entityType, World world ) { super( entityType, world ); }
     
-    //TODO swim behavior
+    /** Override to change this entity's AI goals. */
+    @Override
+    protected void registerVariantGoals() {
+        AIHelper.removeGoals( goalSelector, SwimGoal.class );
+        AIHelper.insertGoal( goalSelector, 5, new AmphibiousGoToWaterGoal<>( this, 1.0 ).alwaysEnabled() );
+    }
     
     /** Override to change the color of this entity's spit attack. */
     @Override

src/main/java/fathertoast/specialmobs/common/entity/silverfish/_SpecialSilverfishEntity.java

@@ -89,6 +89,8 @@ public class _SpecialSilverfishEntity extends SilverfishEntity implements IRange
         super.registerGoals();
         goalSelector.addGoal( 4, new PassiveRangedAttackGoal<>( this ) );
         AIHelper.replaceHurtByTarget( this, new SpecialHurtByTargetGoal( this, SilverfishEntity.class ).setAlertOthers() );
+        // Someday, it would be nice to replace SilverfishEntity.HideInStoneGoal with one that
+        // expands the allowed stone types and preserves species on hide/reveal
         
         registerVariantGoals();
     }

src/main/java/fathertoast/specialmobs/common/entity/slime/BlueberrySlimeEntity.java

@@ -3,21 +3,20 @@ package fathertoast.specialmobs.common.entity.slime;
 import fathertoast.specialmobs.common.bestiary.BestiaryInfo;
 import fathertoast.specialmobs.common.bestiary.MobFamily;
 import fathertoast.specialmobs.common.bestiary.SpecialMob;
-import fathertoast.specialmobs.common.entity.MobHelper;
 import fathertoast.specialmobs.common.entity.ai.AIHelper;
-import fathertoast.specialmobs.common.entity.ai.FluidPathNavigator;
 import fathertoast.specialmobs.common.util.References;
 import fathertoast.specialmobs.datagen.loot.LootTableBuilder;
+import net.minecraft.block.FlowingFluidBlock;
 import net.minecraft.entity.EntityType;
+import net.minecraft.entity.LivingEntity;
 import net.minecraft.entity.ai.attributes.Attributes;
-import net.minecraft.fluid.Fluid;
 import net.minecraft.item.Items;
 import net.minecraft.nbt.CompoundNBT;
 import net.minecraft.particles.IParticleData;
 import net.minecraft.particles.ParticleTypes;
-import net.minecraft.pathfinding.PathNavigator;
 import net.minecraft.pathfinding.PathNodeType;
 import net.minecraft.tags.FluidTags;
+import net.minecraft.util.math.shapes.ISelectionContext;
 import net.minecraft.world.World;
 
 @SpecialMob
@@ -71,21 +70,28 @@ public class BlueberrySlimeEntity extends _SpecialSlimeEntity {
         AIHelper.removeGoals( goalSelector, 1 ); // SlimeEntity.FloatGoal
     }
     
-    /** @return A new path navigator for this entity to use. */
-    @Override
-    protected PathNavigator createNavigation( World world ) {
-        return new FluidPathNavigator( this, world, true, false );
-    }
-    
-    /** @return Whether this entity can stand on a particular type of fluid. */
-    @Override
-    public boolean canStandOnFluid( Fluid fluid ) { return fluid.is( FluidTags.WATER ); }
-    
     /** Called each tick to update this entity. */
     @Override
     public void tick() {
         super.tick();
-        MobHelper.floatInFluid( this, 0.06, FluidTags.WATER );
+        
+        // Hacky way of attacking submerged targets; drop down on them when directly above
+        double floatAccel = 0.06;
+        final LivingEntity target = getTarget();
+        if( target != null && target.getY( 0.5 ) < getY( 0.5 ) ) {
+            //
+            final double dX = target.getX() - getX();
+            final double dZ = target.getZ() - getZ();
+            final float range = (target.getBbWidth() + getBbWidth() + 0.1F) / 2.0F;
+            if( dX * dX + dZ * dZ < range * range )
+                floatAccel = -0.12;
+        }
+        if( tickCount > 1 && getFluidHeight( FluidTags.WATER ) > 0.0 ) {
+            if( !ISelectionContext.of( this ).isAbove( FlowingFluidBlock.STABLE_SHAPE, blockPosition(), true ) ||
+                    level.getFluidState( blockPosition().above() ).is( FluidTags.WATER ) ) {
+                setDeltaMovement( getDeltaMovement().scale( 0.5 ).add( 0.0, floatAccel, 0.0 ) );
+            }
+        }
     }
     
     // The below two methods are here to effectively override the private Entity#isInRain to always return true (always wet)
@@ -95,6 +101,10 @@ public class BlueberrySlimeEntity extends _SpecialSlimeEntity {
     @Override
     public boolean isInWaterRainOrBubble() { return true; }
     
+    /** @return Water drag coefficient. */
+    @Override
+    protected float getWaterSlowDown() { return 0.9F; }
+    
     /** Override to load data from this entity's NBT data. */
     @Override
     public void readVariantSaveData( CompoundNBT saveTag ) {