Fixed armorstand passenger yOffset (#2976)

core/src/main/java/org/geysermc/geyser/entity/type/living/ArmorStandEntity.java

@@ -51,6 +51,7 @@ public class ArmorStandEntity extends LivingEntity {
     @Getter
     private boolean isMarker = false;
     private boolean isInvisible = false;
+    @Getter
     private boolean isSmall = false;
 
     /**
@@ -74,6 +75,7 @@ public class ArmorStandEntity extends LivingEntity {
      * - No armor, no name: false
      * - No armor, yes name: true
      */
+    @Getter
     private boolean positionRequiresOffset = false;
     /**
      * Whether we should update the position of this armor stand after metadata updates.
@@ -411,6 +413,8 @@ public class ArmorStandEntity extends LivingEntity {
             this.positionRequiresOffset = newValue;
             if (positionRequiresOffset) {
                 this.position = applyOffsetToPosition(position);
+                // Update the passenger offset as armorstand is moving up by roughly 2 blocks
+                updatePassengerOffsets();
             } else {
                 this.position = removeOffsetFromPosition(position);
             }

core/src/main/java/org/geysermc/geyser/util/EntityUtils.java

@@ -187,6 +187,15 @@ public final class EntityUtils {
                 case MINECART, HOPPER_MINECART, TNT_MINECART, CHEST_MINECART, FURNACE_MINECART, SPAWNER_MINECART,
                         COMMAND_BLOCK_MINECART, BOAT, CHEST_BOAT -> yOffset -= mount.getDefinition().height() * 0.5f;
             }
+            if (passenger.getDefinition().entityType() == EntityType.FALLING_BLOCK) {
+                yOffset += 0.5f;
+            }
+            if (mount.getDefinition().entityType() == EntityType.ARMOR_STAND) {
+                ArmorStandEntity armorStand = (ArmorStandEntity) mount;
+                if (armorStand.isPositionRequiresOffset()) {
+                    yOffset -= EntityDefinitions.ARMOR_STAND.height() * (armorStand.isSmall() ? 0.55d : 1d);
+                }
+            }
             Vector3f offset = Vector3f.from(xOffset, yOffset, zOffset);
             passenger.setRiderSeatPosition(offset);
         }