Precise Shadowcasting in JavaScript

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### If some part of <code>[a1,a2]</code> is visible, merge it into the shadow queue; mark the cell as '''visible'''
 
### If some part of <code>[a1,a2]</code> is visible, merge it into the shadow queue; mark the cell as '''visible'''
  
== Tweaks, tricks and advanced topics ==
+
== Advanced topics: tricks and tweaks ==
 +
 
 +
=== Cutoff and angle wrapping ===
  
 
=== Symbolic angles ===
 
=== Symbolic angles ===

Revision as of 09:44, 4 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

Advanced topics: tricks and tweaks

Cutoff and angle wrapping

Symbolic angles

Half-angle backward shift

Working with shadow queue

Links

Personal tools