Fancy guns. (#152)

Content.Client/GameObjects/Components/Mobs/CameraRecoilComponent.cs

@@ -0,0 +1,87 @@
+using System;
+using Content.Shared.GameObjects.Components.Mobs;
+using SS14.Client.GameObjects;
+using SS14.Shared.GameObjects;
+using SS14.Shared.Interfaces.GameObjects;
+using SS14.Shared.Interfaces.Network;
+using SS14.Shared.Maths;
+
+namespace Content.Client.GameObjects.Components.Mobs
+{
+    public sealed class CameraRecoilComponent : SharedCameraRecoilComponent
+    {
+        // Maximum rate of magnitude restore towards 0 kick.
+        private const float RestoreRateMax = 1.5f;
+
+        // Minimum rate of magnitude restore towards 0 kick.
+        private const float RestoreRateMin = 0.5f;
+
+        // Time in seconds since the last kick that lerps RestoreRateMin and RestoreRateMax
+        private const float RestoreRateRamp = 0.05f;
+
+        // The maximum magnitude of the kick applied to the camera at any point.
+        private const float KickMagnitudeMax = 0.25f;
+
+        private Vector2 _currentKick;
+        private float _lastKickTime;
+
+        private EyeComponent _eye;
+
+        public override void Initialize()
+        {
+            base.Initialize();
+
+            _eye = Owner.GetComponent<EyeComponent>();
+        }
+
+        public override void Kick(Vector2 recoil)
+        {
+            // Use really bad math to "dampen" kicks when we're already kicked.
+            var existing = _currentKick.Length;
+            var dampen = existing/KickMagnitudeMax;
+            _currentKick += recoil * (1-dampen);
+            if (_currentKick.Length > KickMagnitudeMax)
+            {
+                _currentKick = _currentKick.Normalized * KickMagnitudeMax;
+            }
+
+            _lastKickTime = 0;
+            _updateEye();
+        }
+
+        public override void HandleMessage(ComponentMessage message, INetChannel netChannel = null, IComponent component = null)
+        {
+            base.HandleMessage(message, netChannel, component);
+
+            switch (message)
+            {
+                case RecoilKickMessage msg:
+                    Kick(msg.Recoil);
+                    break;
+            }
+        }
+
+        public void FrameUpdate(float frameTime)
+        {
+            var magnitude = _currentKick.Length;
+            if (magnitude <= 0.005f)
+            {
+                _currentKick = Vector2.Zero;
+                _updateEye();
+                return;
+            }
+
+            // Continually restore camera to 0.
+            var normalized = _currentKick.Normalized;
+            var restoreRate = FloatMath.Lerp(RestoreRateMin, RestoreRateMax, Math.Min(1, _lastKickTime/RestoreRateRamp));
+            var restore = normalized * restoreRate * frameTime;
+            _currentKick -= restore;
+            _updateEye();
+        }
+
+        private void _updateEye()
+        {
+            _eye.Offset = _currentKick;
+        }
+    }
+}