UnderwareDESIGN

Portal Concepts - Screen Space Visibility Systems


  Here's a version of the volume linking idea I mentioned the other day (Watch Video here (https://www.underwaredesign.com/forums/index.php?topic=4838.msg31645#msg31645))..  The take away from the approach is that even though a simplification,  it does seem like it'd be a way more efficient approach.   


About:

     The approach relies on portal-based rendering, a technique where
  only the parts of the game world visible through a series of connected
  portals are drawn. Instead of rendering the entire map, the program:

   - Defines a grid-based map with walls and open spaces.
   - Creates portals that link different areas of the map.
   - Tracks the player's position and viewing angle.
   - Determines which portals are visible within the player's field of view.
   - Recursively checks connected portals to expand the visible area dynamically.
   - Draws only the visible portals, optimizing rendering performance.

    This technique is efficient for large game worlds, as it prevents
 unnecessary drawing of out-of-sight areas. The use of lookup tables and
 visibility lists further improves performance by reducing redundant
 computations.



Download

    Attached bellow

Optimizing Visibility in a 2D Portal System – PlayBASIC Tutorial


 In this tutorial, we take a deep dive into optimizing visibility in a 2D portal system using PlayBASIC. If you're working on a game with interconnected rooms, corridors, or dungeon-like layouts, this technique will help you improve rendering efficiency.
What's Covered?

    Portal-Based Visibility: Define rectangular regions with shared walls to create a network of connected areas.
    Dynamic Region Traversal: Use a stack-based approach instead of recursion for efficient visibility detection.
    Performance Optimizations: Implement visibility culling, limit view distance, and refine the field of view to reduce overdraw.

By ensuring only necessary areas and objects are processed, these optimizations can significantly boost performance in 2D games. This method is especially useful for top-down RPGs, maze-based games, or any project where managing visibility efficiently is key.

Watch the full tutorial here:

 
Let me know if you have any questions or ideas for improvements!

Portal Concepts - Screen Space Visibility Systems V0.03


  Here's a revision of the demo.  This version has the code more broken up into something more like a set of libraries than one big blog of code. 



 Related Examples

   -- Line intersects Triangle (https://www.underwaredesign.com/forums/index.php?topic=4842.0)



Download

    Attached bellow