Add on_move Entity Event for Scarpet (#1096)

* Add ON_MOVE Entity Event for Scarpet

* Update src/main/java/carpet/script/EntityEventsGroup.java

* Add on_move to Entities.md

* Switch to ValueConversions

* Update docs/scarpet/api/Entities.md

Co-authored-by: gnembon <41132274+gnembon@users.noreply.github.com>

* Fix #1126

* undo last commit cause it was on the wrong branch

Co-authored-by: gnembon <41132274+gnembon@users.noreply.github.com>

docs/scarpet/api/Entities.md

@@ -858,6 +858,7 @@ defining the callback with `entity_event`.
 The following events can be handled by entities:
 
 *   `'on_tick'`: executes every tick right before the entity is ticked in the game. Required arguments: `entity`
+*   `'on_move'`: executes every time an entity changes position, invoked just after it has been moved to the new position. Required arguments: `entity, velocity, pos1, pos2`
 *   `'on_death'`: executes once when a living entity dies. Required arguments: `entity, reason`
 *   `'on_removed'`: execute once when an entity is removed. Required arguments: `entity`
 *   `'on_damaged'`: executed every time a living entity is about to receive damage.

src/main/java/carpet/mixins/Entity_scarpetEventsMixin.java

@@ -3,6 +3,7 @@ package carpet.mixins;
 import carpet.fakes.EntityInterface;
 import carpet.script.EntityEventsGroup;
 import net.minecraft.entity.Entity;
+import net.minecraft.util.math.Vec3d;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.Shadow;
 import org.spongepowered.asm.mixin.injection.At;
@@ -19,10 +20,14 @@ public abstract class Entity_scarpetEventsMixin implements EntityInterface
 
     @Shadow public abstract boolean isRemoved();
 
+    @Shadow private Vec3d pos, velocity;
+
     private boolean permanentVehicle;
 
     private final EntityEventsGroup events = new EntityEventsGroup((Entity) (Object)this);
 
+    private Vec3d pos1, motion;
+
     @Override
     public EntityEventsGroup getEventContainer()
     {
@@ -79,4 +84,16 @@ public abstract class Entity_scarpetEventsMixin implements EntityInterface
     }
 
 
+    @Inject(method = "setPos", at = @At("HEAD"))
+    private void firstPos(CallbackInfo ci)
+    {
+        pos1 = this.pos;
+        motion = this.velocity;
+    }
+
+    @Inject(method = "setPos", at = @At("TAIL"))
+    private void secondPos(CallbackInfo ci)
+    {
+        events.onEvent(EntityEventsGroup.Event.ON_MOVE, motion, pos1, this.pos);
+    }
 }

src/main/java/carpet/script/EntityEventsGroup.java

@@ -7,8 +7,10 @@ import carpet.script.value.FunctionValue;
 import carpet.script.value.NumericValue;
 import carpet.script.value.StringValue;
 import carpet.script.value.Value;
+import carpet.script.value.ValueConversions;
 import net.minecraft.entity.Entity;
 import net.minecraft.entity.damage.DamageSource;
+import net.minecraft.util.math.Vec3d;
 
 import java.util.Arrays;
 import java.util.Collections;
@@ -108,6 +110,19 @@ public class EntityEventsGroup
                 );
             }
         };
+        public static final Event ON_MOVE = new Event("on_move", 3)
+        {
+            @Override
+            public List<Value> makeArgs(Entity entity, Object... providedArgs)
+            {
+                return Arrays.asList(
+                        new EntityValue(entity),
+                        ValueConversions.of((Vec3d) providedArgs[0]),
+                        ValueConversions.of((Vec3d) providedArgs[1]),
+                        ValueConversions.of((Vec3d) providedArgs[2])
+                );
+            }
+        };
 
         public final int argcount;
         public final String id;