Thrown Item Physics (#120)

* Thrown object speed is now based on force.
Fixed BoundingBox namespace.

* 100% more throwing.
CollisionGroup enum.

* Update Engine.

Content.Server/Content.Server.csproj

@@ -90,6 +90,7 @@
     <Compile Include="GameObjects\Components\Power\PowerStorageNetComponent.cs" />
     <Compile Include="GameObjects\Components\Power\PowerTransferComponent.cs" />
     <Compile Include="GameObjects\Components\Projectiles\ProjectileComponent.cs" />
+    <Compile Include="GameObjects\Components\Projectiles\ThrownItemComponent.cs" />
     <Compile Include="GameObjects\Components\Weapon\Melee\MeleeWeaponComponent.cs" />
     <Compile Include="GameObjects\Components\Weapon\Ranged\Hitscan\HitscanWeaponComponent.cs" />
     <Compile Include="GameObjects\Components\Weapon\Ranged\Projectile\ProjectileWeapon.cs" />

Content.Server/EntryPoint.cs

@@ -1,4 +1,5 @@
 using Content.Server.GameObjects;
+using Content.Server.GameObjects.Components;
 using Content.Server.GameObjects.Components.Power;
 using Content.Server.GameObjects.Components.Interactable.Tools;
 using Content.Server.Interfaces.GameObjects;
@@ -104,6 +105,7 @@ namespace Content.Server
             factory.Register<HitscanWeaponComponent>();
             factory.Register<ProjectileWeaponComponent>();
             factory.Register<ProjectileComponent>();
+            factory.Register<ThrownItemComponent>();
             factory.Register<MeleeWeaponComponent>();
 
             factory.Register<HandheldLightComponent>();

Content.Server/GameObjects/Components/Projectiles/ThrownItemComponent.cs

@@ -0,0 +1,36 @@
+using System.Collections.Generic;
+using Content.Server.GameObjects.Components.Projectiles;
+using Content.Shared.Physics;
+using SS14.Shared.Interfaces.GameObjects;
+using SS14.Shared.Interfaces.GameObjects.Components;
+
+namespace Content.Server.GameObjects.Components
+{
+    class ThrownItemComponent : ProjectileComponent, ICollideBehavior
+    {
+        public override string Name => "ThrownItem";
+
+        void ICollideBehavior.CollideWith(List<IEntity> collidedwith)
+        {
+            foreach (var entity in collidedwith)
+            {
+                if (entity.TryGetComponent(out DamageableComponent damage))
+                {
+                    damage.TakeDamage(DamageType.Brute, 10);
+                }
+            }
+
+            // Stop colliding with mobs, this mimics not having enough velocity to do damage
+            // after impacting the first object.
+            // For realism this should actually be changed when the velocity of the object is less than a threshold.
+            // This would allow ricochets off walls, and weird gravity effects from slowing the object.
+            if (collidedwith.Count > 0 && Owner.TryGetComponent(out ICollidableComponent body))
+            {
+                body.CollisionMask &= (int) ~CollisionGroup.Mob;
+
+                // KYS, your job is finished.
+                Owner.RemoveComponent<ThrownItemComponent>();
+            }
+        }
+    }
+}

Content.Server/GameObjects/EntitySystems/Click/InteractionSystem.cs

@@ -14,7 +14,6 @@ using SS14.Server.GameObjects;
 using SS14.Server.GameObjects.EntitySystems;
 using SS14.Server.Interfaces.Player;
 using SS14.Shared.Interfaces.GameObjects.Components;
-using SS14.Shared.GameObjects.Components.BoundingBox;
 using SS14.Shared.Players;
 
 namespace Content.Server.GameObjects.EntitySystems

Content.Server/GameObjects/EntitySystems/HandsSystem.cs

@@ -1,6 +1,9 @@
 using System;
+using Content.Server.GameObjects.Components;
 using Content.Server.GameObjects.Components.Projectiles;
+using Content.Server.GameObjects.Components.Stack;
 using Content.Shared.Input;
+using Content.Shared.Physics;
 using SS14.Server.GameObjects;
 using SS14.Server.GameObjects.EntitySystems;
 using SS14.Server.Interfaces.Player;
@@ -8,7 +11,10 @@ using SS14.Shared.GameObjects;
 using SS14.Shared.GameObjects.EntitySystemMessages;
 using SS14.Shared.GameObjects.Systems;
 using SS14.Shared.Input;
+using SS14.Shared.Interfaces.GameObjects;
 using SS14.Shared.Interfaces.GameObjects.Components;
+using SS14.Shared.Interfaces.Timing;
+using SS14.Shared.IoC;
 using SS14.Shared.Map;
 using SS14.Shared.Maths;
 using SS14.Shared.Players;
@@ -17,7 +23,7 @@ namespace Content.Server.GameObjects.EntitySystems
 {
     internal class HandsSystem : EntitySystem
     {
-        private const float ThrowSpeed = 1.0f;
+        private const float ThrowForce = 1.5f; // Throwing force of mobs in Newtons
 
         /// <inheritdoc />
         public override void Initialize()
@@ -133,14 +139,40 @@ namespace Content.Server.GameObjects.EntitySystems
             if (!plyEnt.TryGetComponent(out HandsComponent handsComp))
                 return;
 
-            if (handsComp.CanDrop(handsComp.ActiveIndex))
-            {
-                var throwEnt = handsComp.GetHand(handsComp.ActiveIndex).Owner;
-                handsComp.Drop(handsComp.ActiveIndex, null);
+            if (!handsComp.CanDrop(handsComp.ActiveIndex))
+                return;
 
-                if (!throwEnt.TryGetComponent(out ProjectileComponent projComp))
+            var throwEnt = handsComp.GetHand(handsComp.ActiveIndex).Owner;
+
+            // pop off an item, or throw the single item in hand.
+            if (!throwEnt.TryGetComponent(out StackComponent stackComp) || stackComp.Count < 2)
             {
-                    projComp = throwEnt.AddComponent<ProjectileComponent>();
+                handsComp.Drop(handsComp.ActiveIndex, null);
+            }
+            else
+            {
+                stackComp.Use(1);
+                throwEnt = throwEnt.EntityManager.ForceSpawnEntityAt(throwEnt.Prototype.ID, plyEnt.Transform.LocalPosition);
+            }
+            
+            if (!throwEnt.TryGetComponent(out CollidableComponent colComp))
+            {
+                colComp = throwEnt.AddComponent<CollidableComponent>();
+
+                if(!colComp.Running)
+                    colComp.Startup();
+            }
+
+            colComp.CollisionEnabled = true;
+            colComp.CollisionLayer |= (int)CollisionGroup.Items;
+            colComp.CollisionMask |= (int)CollisionGroup.Grid;
+
+            // I can now collide with player, so that i can do damage.
+            colComp.CollisionMask |= (int) CollisionGroup.Mob;
+
+            if (!throwEnt.TryGetComponent(out ThrownItemComponent projComp))
+            {
+                projComp = throwEnt.AddComponent<ThrownItemComponent>();
             }
             
             projComp.IgnoreEntity(plyEnt);
@@ -153,22 +185,20 @@ namespace Content.Server.GameObjects.EntitySystems
                 physComp = throwEnt.AddComponent<PhysicsComponent>();
             }
 
-                physComp.LinearVelocity = dirVec * ThrowSpeed;
+            // TODO: Move this into PhysicsSystem, we need an ApplyForce function.
+            var a = ThrowForce / (float) Math.Max(0.001, physComp.Mass); // a = f / m
 
+            var timing = IoCManager.Resolve<IGameTiming>();
+            var spd = a / (1f / timing.TickRate); // acceleration is applied in 1 tick instead of 1 second, scale appropriately
+
+            physComp.LinearVelocity = dirVec * spd;
 
             var wHomoDir = Vector3.UnitX;
 
             transform.InvWorldMatrix.Transform(ref wHomoDir, out var lHomoDir);
 
             lHomoDir.Normalize();
-                var angle = new Angle(lHomoDir.Xy);
-
-                transform.LocalRotation = angle;
-            }
-            else
-            {
-                return;
-            }
+            transform.LocalRotation = new Angle(lHomoDir.Xy);
         }
     }
 }

Content.Shared/Content.Shared.csproj

@@ -71,6 +71,7 @@
     <Compile Include="GameObjects\Components\Storage\SharedStorageComponent.cs" />
     <Compile Include="GameObjects\ContentNetIDs.cs" />
     <Compile Include="GameObjects\PhysicalConstants.cs" />
+    <Compile Include="Physics\CollisionGroup.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="GameObjects\Components\Items\SharedHandsComponent.cs" />
     <Compile Include="GameObjects\Components\Power\SharedPowerDebugTool.cs" />

Content.Shared/Physics/CollisionGroup.cs

@@ -0,0 +1,17 @@
+using System;
+
+namespace Content.Shared.Physics
+{
+    /// <summary>
+    ///     Defined collision groups for the physics system.
+    /// </summary>
+    [Flags]
+    public enum CollisionGroup
+    {
+        None = 0x0000,
+        Grid = 0x0001, // Walls
+        Mob = 0x0002, // Mobs, like the player or NPCs
+        Fixture = 0x0004, // wall fixtures, like APC or posters
+        Items = 0x008, // Items on the ground
+    }
+}