Packet: ObjectDetachMessage (#116)

* initial ObjectDetachMessage packet and tests

* discovered how to orient the dropped item

common/src/main/scala/net/psforever/packet/GamePacketOpcode.scala

@@ -364,7 +364,7 @@ object GamePacketOpcode extends Enumeration {
     case 0x24 => game.SetEmpireMessage.decode
     case 0x25 => game.EmoteMsg.decode
     case 0x26 => noDecoder(UnuseItemMessage)
-    case 0x27 => noDecoder(ObjectDetachMessage)
+    case 0x27 => game.ObjectDetachMessage.decode
     // 0x28
     case 0x28 => game.CreateShortcutMessage.decode
     case 0x29 => game.ChangeShortcutBankMessage.decode

common/src/main/scala/net/psforever/packet/game/DropItemMessage.scala

@@ -5,6 +5,18 @@ import net.psforever.packet.{GamePacketOpcode, Marshallable, PacketHelpers, Plan
 import scodec.Codec
 import scodec.codecs._
 
+/**
+  * Dispatched by the client when the player's intent is to put an item down on the ground.<br>
+  * <br>
+  * When a player drops an item, it normally appears right under their feet (where they are standing).
+  * This part of the ground is chosen because it should be the stable.
+  * Also, those coordinates belonging to the player are the most accessible.
+  * This process, however, is not automatic.
+  * The server determines the exact position where the item gets placed.<br>
+  * <br>
+  * This packet is complemented by an `ObjectDetachMessage` packet from the server that performs the actual "dropping."
+  * @param item_guid the item to be dropped
+  */
 final case class DropItemMessage(item_guid : PlanetSideGUID)
   extends PlanetSideGamePacket {
   type Packet = DropItemMessage
@@ -14,6 +26,6 @@ final case class DropItemMessage(item_guid : PlanetSideGUID)
 
 object DropItemMessage extends Marshallable[DropItemMessage] {
   implicit val codec : Codec[DropItemMessage] = (
-      ("item_guid" | PlanetSideGUID.codec)
+      "item_guid" | PlanetSideGUID.codec
     ).as[DropItemMessage]
 }

common/src/main/scala/net/psforever/packet/game/ObjectDetachMessage.scala

@@ -0,0 +1,60 @@
+// Copyright (c) 2017 PSForever
+package net.psforever.packet.game
+
+import net.psforever.packet.{GamePacketOpcode, Marshallable, PlanetSideGamePacket}
+import net.psforever.types.Vector3
+import scodec.Codec
+import scodec.codecs._
+
+/**
+  * Dispatched by the server to cause two associated objects to disentangle from one another.<br>
+  * <br>
+  * `ObjectDetachMessage` is the opposite to `ObjectAttachMessage`.
+  * When detached, the resulting freed object will be placed at the given coordinates.
+  * For some container objects, most often static ones, a default placement point does exist.
+  * This usually matches the position where the original mounting occurred, or is relative to the current position of the container.
+  * Using a position that is not the mounting one, in this case, counts as a temporary teleport of the character.
+  * As soon as available, e.g., the end of an animation, the character will rw-appear at the mounting point.
+  * The object may also have its orientation aspect changed.<br>
+  * <br>
+  * This packet is considered proper response to:<br>
+  * - `DismountVehicleMsg`<br>
+  * - `DropItemMessage`
+  * @param parent_guid the container/connector object
+  * @param child_guid the contained/connected object
+  * @param pos where the contained/connected object will be placed after it has detached
+  * @param roll the roll of the dropped item;
+  *             every `0x1` is 2.813 degrees;
+  *             every `0x10` is 45-degrees;
+  *             it wraps at `0x0` == `0x80` == top facing up
+  * @param pitch the pitch of the dropped item;
+  *              every `0x1` is 2.813 degrees;
+  *              every `0x10` is 45-degrees;
+  *             it wraps at `0x0` == `0x80` == top facing up
+  * @param yaw the yaw of the dropped item;
+  *            every `0x1` is 2.813 degrees counter clockwise from East;
+  *            every `0x10` is 45-degrees;
+  *            it wraps at `0x0` == `0x80` == front facing East
+  */
+final case class ObjectDetachMessage(parent_guid : PlanetSideGUID,
+                                     child_guid : PlanetSideGUID,
+                                     pos : Vector3,
+                                     roll : Int,
+                                     pitch : Int,
+                                     yaw : Int)
+  extends PlanetSideGamePacket {
+  type Packet = ObjectDetachMessage
+  def opcode = GamePacketOpcode.ObjectDetachMessage
+  def encode = ObjectDetachMessage.encode(this)
+}
+
+object ObjectDetachMessage extends Marshallable[ObjectDetachMessage] {
+  implicit val codec : Codec[ObjectDetachMessage] = (
+    ("parent_guid" | PlanetSideGUID.codec) ::
+      ("child_guid" | PlanetSideGUID.codec) ::
+      ("pos" | Vector3.codec_pos) ::
+      ("roll" | uint8L) ::
+      ("pitch" | uint8L) ::
+      ("yaw" | uint8L)
+    ).as[ObjectDetachMessage]
+}

common/src/test/scala/game/ObjectDetachMessageTest.scala

@@ -0,0 +1,35 @@
+// Copyright (c) 2017 PSForever
+package game
+
+import org.specs2.mutable._
+import net.psforever.packet._
+import net.psforever.packet.game._
+import net.psforever.types.Vector3
+import scodec.bits._
+
+class ObjectDetachMessageTest extends Specification {
+  val string = hex"27 640B C609 92F76 01D65 F611 00 00 40"
+
+  "decode" in {
+    PacketCoding.DecodePacket(string).require match {
+      case ObjectDetachMessage(parent_guid, child_guid, pos, roll, pitch, yaw) =>
+        parent_guid mustEqual PlanetSideGUID(2916)
+        child_guid mustEqual PlanetSideGUID(2502)
+        pos.x mustEqual 3567.1406f
+        pos.y mustEqual 2988.0078f
+        pos.z mustEqual 71.84375f
+        roll mustEqual 0
+        pitch mustEqual 0
+        yaw mustEqual 64
+      case _ =>
+        ko
+    }
+  }
+
+  "encode" in {
+    val msg = ObjectDetachMessage(PlanetSideGUID(2916), PlanetSideGUID(2502), Vector3(3567.1406f, 2988.0078f, 71.84375f), 0, 0, 64)
+    val pkt = PacketCoding.EncodePacket(msg).require.toByteVector
+
+    pkt mustEqual string
+  }
+}

pslogin/src/main/scala/WorldSessionActor.scala

@@ -279,6 +279,8 @@ class WorldSessionActor extends Actor with MDCContextAware {
       sendResponse(PacketCoding.CreateGamePacket(0, EmoteMsg(avatar_guid, emote)))
 
     case msg @ DropItemMessage(item_guid) =>
+      //item dropped where you spawn in VS Sanctuary
+      sendResponse(PacketCoding.CreateGamePacket(0, ObjectDetachMessage(PlanetSideGUID(75), item_guid, app.pos, 0, 0, 0)))
       log.info("DropItem: " + msg)
 
     case msg @ ReloadMessage(item_guid, ammo_clip, unk1) =>