Precise Shadowcasting in JavaScript

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== Links ==
 
== Links ==
  
* [[http://jsfiddle.net/ondras/ycJVj/|Interactive demo]]
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* [http://jsfiddle.net/ondras/ycJVj/|Interactive demo]
* [[http://ondras.github.com/rot.js/manual/#fov|rot.js FOV manual]]
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* [http://ondras.github.com/rot.js/manual/#fov|rot.js FOV manual]
* [[https://raw.github.com/ondras/rot.js/master/src/fov/precise-shadowcasting.js|Source code]]
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* [https://raw.github.com/ondras/rot.js/master/src/fov/precise-shadowcasting.js|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.

WORK IN PROGRESS

Contents

About

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

Links

Personal tools