- add: TelescopeSystem. (#273)

Content.Client/_White/Telescope/TelescopeSystem.cs

@@ -0,0 +1,70 @@
+using System.Numerics;
+using Content.Shared._White.Telescope;
+using Content.Shared.Hands.Components;
+using Robust.Client.GameObjects;
+using Robust.Client.Graphics;
+using Robust.Client.Input;
+using Robust.Client.Player;
+using Robust.Shared.Input;
+using Robust.Shared.Timing;
+
+namespace Content.Client._White.Telescope;
+
+public sealed class TelescopeSystem : SharedTelescopeSystem
+{
+    [Dependency] private readonly InputSystem _inputSystem = default!;
+    [Dependency] private readonly IGameTiming _timing = default!;
+    [Dependency] private readonly IPlayerManager _player = default!;
+    [Dependency] private readonly IInputManager _input = default!;
+    [Dependency] private readonly IEyeManager _eyeManager = default!;
+
+    public override void Update(float frameTime)
+    {
+        base.Update(frameTime);
+
+        if (_timing.ApplyingState || !_timing.IsFirstTimePredicted || !_input.MouseScreenPosition.IsValid)
+            return;
+
+        var player = _player.LocalEntity;
+
+        if (!TryComp<HandsComponent>(player, out var hands) ||
+            !TryComp<TelescopeComponent>(hands.ActiveHandEntity, out var telescope) ||
+            !TryComp<EyeComponent>(player.Value, out var eye) || !TryComp(player.Value, out TransformComponent? xform))
+            return;
+
+        var offset = Vector2.Zero;
+
+        if (_inputSystem.CmdStates.GetState(EngineKeyFunctions.UseSecondary) != BoundKeyState.Down)
+        {
+            RaisePredictiveEvent(new EyeOffsetChangedEvent
+            {
+                Offset = offset
+            });
+            return;
+        }
+
+        var mousePos = _input.MouseScreenPosition.Position;
+        var playerPos = _eyeManager.CoordinatesToScreen(xform.Coordinates).Position;
+
+        var diff = mousePos - playerPos;
+        var len = diff.Length();
+
+        if (len > telescope.MaxLength)
+        {
+            diff *= telescope.MaxLength / len;
+            len = telescope.MaxLength;
+        }
+
+        if (len > telescope.MinLength)
+        {
+            diff -= diff * telescope.MinLength / len;
+            offset = new Vector2(diff.X / telescope.Divisor, -diff.Y / telescope.Divisor);
+            offset = new Angle(-eye.Rotation.Theta).RotateVec(offset);
+        }
+
+        RaisePredictiveEvent(new EyeOffsetChangedEvent
+        {
+            Offset = offset
+        });
+    }
+}