shader - Unity UI - Applying mask to individual sprites instead of entire texture - Stack Overflow
Inverse UI Mask | Game Content Shopper – Unity Asset Store™ Sales and Price Drops
GitHub - mob-sakai/SoftMaskForUGUI: UI Soft Mask is a smooth masking component for Unity UI (uGUI) elements.
GitHub - mob-sakai/UnmaskForUGUI: A reverse masking solution for uGUI element in Unity.
shader - Unity UI mask does not work on children with different Canvas component and particles - Stack Overflow
Depth Mask / Reverse UI Mask for UI staying on screen even when disabled,Depth Mask / Reverse Mask in UI remain transparent even when disabled - Questions & Answers - Unity Discussions