Precise Shadowcasting in JavaScript

From RogueBasin
(Difference between revisions)
Jump to: navigation, search
Line 28: Line 28:
== Links ==
== Links ==
* [[|Interactive demo]]
* [|Interactive demo]
* [[|rot.js FOV manual]]
* [|rot.js FOV manual]
* [[|Source code]]
* [|Source code]

Revision as of 17:29, 3 January 2013

This pages describes and explains the Precise Shadowcasting algorithm, developed and implemented by Ondřej Žára in rot.js.




General algorithm workflow

  1. Let [x,y] be the player coordinates
  2. Initialize the empty shadow queue
  3. For R=1 up to maximum visibility range do:
    1. Retrieve all cells whose range from [x,y] is R
    2. Make sure these cells are in correct order (clockwise or counter-clockwise; every iteration starting at the same angle)
    3. For every cell in this "ring":
      1. Determine the corresponding arc [a1,a2]
      2. Consult the shadow queue to determine whether [a1,a2] is fully shadowed
      3. If no part of [a1,a2] is visible, mark the cell as not visible and advance to next cell
      4. If some part of [a1,a2] is visible, merge it into the shadow queue; mark the cell as visible

Tweaks, tricks and advanced topics

Symbolic angles

Half-angle backward shift

Working with shadow queue


Personal tools