Difference between revisions of "Field of Vision"

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It's common to check the [[visiblity]] of many objects from one point on the map. For example, you might want to know which parts of map are visible from the place the player character is standing, to draw those parts of map on the screen.
Some of the most important features on roguelikes, including the presentation of the area that surrounds the player character, require to check the visibility of an object from a given point on the map. For example, it may be necessary to know which parts of map are visible from the place the player character is standing to draw those parts of map on the screen.


You might just use the [[Line of Sight]] to check all the map squares in range, but that's pretty slow, and you're repeating most of the calculations mulitple times. It is much better to calculate the [[Field of Vision]] as a whole.
There are basically two ways to achieve this; by using [[Line of Sight]] to check all the map squares in range, which is a slow method as it repeats most of the calculations multiple times, or by calculating the [[Field of Vision]] as a whole.
 
There are several ways to do it:


Some of the most common approaches to field of vision are:
* Light whole level. Just make everything visible, or at least everything close to the player. Many games use this approach and it seems to work.
* Light whole level. Just make everything visible, or at least everything close to the player. Many games use this approach and it seems to work.
 
* Light whole room. This is the approach used by the original [[Rogue]]. You just make the whole room in which the player character is visible, and all other parts of map not visible. When the character is in a corridor, it can only see one square from where he stands, this doesn't require any sophisticated calculations.
* Light whole room. This is the apporach used by the original [[Rogue]]. You just make the whole room in which the player character is visible, and all other parts of map -- not visible. When the character is in a corridor, it can only see one square from where he stands -- this doesn't require any sophisticated calculations.
 
* [[Ray casting]]
* [[Ray casting]]
* [[Shadow casting]]
* [[Recursive shadow casting]]


* [[Shadow casting]]


* [[Recursive shadow casting]]
== Available Libraries ==


[[libfov]] can do a lot of the work for you.
* [[libfov]] is a C++ library made by [[Blue Puyo]], which supports both circular FoV and Beams


[[Category:Algorithms]]
[[Category:Algorithms]]

Revision as of 16:06, 8 April 2006

Some of the most important features on roguelikes, including the presentation of the area that surrounds the player character, require to check the visibility of an object from a given point on the map. For example, it may be necessary to know which parts of map are visible from the place the player character is standing to draw those parts of map on the screen.

There are basically two ways to achieve this; by using Line of Sight to check all the map squares in range, which is a slow method as it repeats most of the calculations multiple times, or by calculating the Field of Vision as a whole.

Some of the most common approaches to field of vision are:

  • Light whole level. Just make everything visible, or at least everything close to the player. Many games use this approach and it seems to work.
  • Light whole room. This is the approach used by the original Rogue. You just make the whole room in which the player character is visible, and all other parts of map not visible. When the character is in a corridor, it can only see one square from where he stands, this doesn't require any sophisticated calculations.
  • Ray casting
  • Shadow casting
  • Recursive shadow casting


Available Libraries

  • libfov is a C++ library made by Blue Puyo, which supports both circular FoV and Beams