Version 1.4b is released. The updated version can be found and downloaded from the itch.io page. Due to some fundamental changes, the Demo also have been updated for the sake of visualizing changes. 

Change-log:

- Re-written the shadow polygon optimization, which both fixed most weird lighting box when drawing unusual shadow shapes, and drastically reduce the shadow segments numbers by roughly 10% (which lead to faster performance). 

- Re-organized the region id usage, counting from zero height so that mean now you can draw 0-height shadow caster block, or can be call as top-down-2D-block. You will need to increase the old region id by 1 though. Also now you can limited the region id block by a range instead of only start index like before (default is from 1 to 10). 

- Introduce two more special block that can be specified its id (default is 50 and 51): top-roof block and ignore-shadows block. Top-roof block serve the purpose of draw top roof, which no light can be cast on it (useful when you drawing a gate, etc.) and ignore-shadow block will NOT let any shadow ray to be cast on it (can be use when you want to make the illusion of a wall that is higher than the light ray, which the shadow cannot cast to).

- Fixed some minor bugs (the one @Nerine noted). 

Feel free to try it out, and remember to return your feedbacks! All suggestion are welcomed ;)