Add before-lighting overlay rendering

Kinda eh but need some way to draw to overlays before lighting is run and all overlays come after.

Robust.Client/Graphics/Clyde/Clyde.LightRendering.cs

@@ -16,6 +16,7 @@
 using TKStencilOp = OpenToolkit.Graphics.OpenGL4.StencilOp;
 using Robust.Shared.Physics;
 using Robust.Client.ComponentTrees;
+using Robust.Shared.Enums;
 using Robust.Shared.Graphics;
 using static Robust.Shared.GameObjects.OccluderComponent;
 using Robust.Shared.Utility;
@@ -514,6 +515,8 @@ private void DrawLightsAndFov(Viewport viewport, Box2Rotated worldBounds, Box2 w
 
             CheckGlError();
 
+            RenderOverlays(viewport, OverlaySpace.BeforeLighting, worldAABB, worldBounds);
+
             if (_cfg.GetCVar(CVars.LightBlur))
                 BlurLights(viewport, eye);
 

Robust.Client/Graphics/IRenderTarget.cs

@@ -1,4 +1,6 @@
 using System;
+using System.Numerics;
+using Robust.Shared.Graphics;
 using Robust.Shared.Maths;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -9,6 +11,43 @@ namespace Robust.Client.Graphics
     /// </summary>
     public interface IRenderTarget : IDisposable
     {
+        public Vector2 LocalToWorld(IEye eye, Vector2 point, Vector2 scale)
+        {
+            var newPoint = point;
+
+            // (inlined version of UiProjMatrix^-1)
+            newPoint -= Size / 2f;
+            newPoint *= new Vector2(1, -1) / EyeManager.PixelsPerMeter;
+
+            // view matrix
+            eye.GetViewMatrixInv(out var viewMatrixInv, scale);
+            newPoint = Vector2.Transform(newPoint, viewMatrixInv);
+
+            return newPoint;
+        }
+
+        public Vector2 WorldToLocal(Vector2 point, IEye eye, Vector2 scale)
+        {
+            var newPoint = point;
+
+            eye.GetViewMatrix(out var viewMatrix, scale);
+            newPoint = Vector2.Transform(newPoint, viewMatrix);
+
+            // (inlined version of UiProjMatrix)
+            newPoint *= new Vector2(1, -1) * EyeManager.PixelsPerMeter;
+            newPoint += Size / 2f;
+
+            return newPoint;
+        }
+
+        public Matrix3x2 GetWorldToLocalMatrix(IEye eye, Vector2 scale)
+        {
+            eye.GetViewMatrix(out var viewMatrix, scale * new Vector2(EyeManager.PixelsPerMeter, -EyeManager.PixelsPerMeter));
+            viewMatrix.M31 += Size.X / 2f;
+            viewMatrix.M32 += Size.Y / 2f;
+            return viewMatrix;
+        }
+
         /// <summary>
         ///     The size of the render target, in physical pixels.
         /// </summary>

Robust.Shared/Enums/OverlaySpaces.cs

@@ -54,6 +54,11 @@ public enum OverlaySpace : ushort
         /// <summary>
         ///     Overlay will be rendered below grids, entities, and everything else. In world space.
         /// </summary>
-        WorldSpaceBelowWorld = 1 << 8
+        WorldSpaceBelowWorld = 1 << 8,
+
+        /// <summary>
+        ///     Overlay will be drawn before lighting occurs. Used to apply changes to the lighting render target.
+        /// </summary>
+        BeforeLighting = 1 << 9,
     }
 }