AlphaMask now affects all of its descendants

Author: sa-exe

src/NitroSharp/Graphics/RenderItem.cs

@@ -264,6 +264,17 @@ public override bool IsIdle
         protected virtual (Vector2, Vector2) GetTexCoords(RenderContext ctx)
             => (Vector2.Zero, Vector2.One);
 
+        protected AlphaMask? TryGetAlphaMaskAscendant()
+        {
+            Entity? current = Parent;
+            while (current is not (AlphaMask or null))
+            {
+                current = current.Parent;
+            }
+
+            return current as AlphaMask;
+        }
+
         protected override void AdvanceAnimations(RenderContext ctx, float dt, bool assetsReady)
         {
             base.AdvanceAnimations(ctx, dt, assetsReady);

src/NitroSharp/Graphics/RenderItems/Sprite.cs

@@ -229,7 +229,7 @@ protected override void Render(RenderContext ctx, DrawBatch drawBatch)
         {
             Texture alphaMaskTex = ctx.WhiteTexture;
             Vector2 alphaMaskPos = Vector2.Zero;
-            if (Parent is AlphaMask alphaMask)
+            if (TryGetAlphaMaskAscendant() is { } alphaMask)
             {
                 alphaMaskTex = ctx.Content.Get(alphaMask.Texture);
                 alphaMaskPos = alphaMask.Transform.Position.XY();