Decal placement preview (#13460)

Content.Client/Decals/Overlays/DecalPlacementOverlay.cs

@@ -0,0 +1,67 @@
+using Robust.Client.GameObjects;
+using Robust.Client.Graphics;
+using Robust.Client.Input;
+using Robust.Shared.Enums;
+using Robust.Shared.Map;
+
+namespace Content.Client.Decals.Overlays;
+
+public sealed class DecalPlacementOverlay : Overlay
+{
+    [Dependency] private readonly IEyeManager _eyeManager = default!;
+    [Dependency] private readonly IInputManager _inputManager = default!;
+    [Dependency] private readonly IMapManager _mapManager = default!;
+    private readonly DecalPlacementSystem _placement;
+    private readonly SharedTransformSystem _transform;
+    private readonly SpriteSystem _sprite;
+
+    public override OverlaySpace Space => OverlaySpace.WorldSpace;
+
+    public DecalPlacementOverlay(DecalPlacementSystem placement, SharedTransformSystem transform, SpriteSystem sprite)
+    {
+        IoCManager.InjectDependencies(this);
+        _placement = placement;
+        _transform = transform;
+        _sprite = sprite;
+    }
+
+    protected override void Draw(in OverlayDrawArgs args)
+    {
+        var (decal, snap, rotation, color) = _placement.GetActiveDecal();
+
+        if (decal == null)
+            return;
+
+        var mouseScreenPos = _inputManager.MouseScreenPosition;
+        var mousePos = _eyeManager.ScreenToMap(mouseScreenPos);
+
+        if (mousePos.MapId != args.MapId)
+            return;
+
+        // No map support for decals
+        if (!_mapManager.TryFindGridAt(mousePos, out var grid))
+        {
+            return;
+        }
+
+        var worldMatrix = _transform.GetWorldMatrix(grid.Owner);
+        var invMatrix = _transform.GetInvWorldMatrix(grid.Owner);
+
+        var handle = args.WorldHandle;
+        handle.SetTransform(worldMatrix);
+
+        var localPos = invMatrix.Transform(mousePos.Position);
+
+        if (snap)
+        {
+            localPos = (Vector2) localPos.Floored() + grid.TileSize / 2f;
+        }
+
+        // Nothing uses snap cardinals so probably don't need preview?
+        var aabb = Box2.UnitCentered.Translated(localPos);
+        var box = new Box2Rotated(aabb, rotation, localPos);
+
+        handle.DrawTextureRect(_sprite.Frame0(decal.Sprite), box, color);
+        handle.SetTransform(Matrix3.Identity);
+    }
+}