Talk:Lighting effects

From DoomWiki.org

Revision as of 14:46, 5 July 2014 by Quasar (talk | contribs) (A bit about steps of 16 units)

Recent dwforums post mentioning this article: [1].  Changing it would just replace one unreferenced statement with another — a source code excerpt would be more reassuring, but I can't find one.    Ryan W (talk) 16:27, 5 July 2014 (UTC)

This is the function which thinks for a fire flicker effect every tic:

<source lang="C"> // // T_FireFlicker // void T_FireFlicker (fireflicker_t* flick) {

   int	amount;
   if (--flick->count)

return;

   amount = (P_Random()&3)*16;
   
   if (flick->sector->lightlevel - amount < flick->minlight)

flick->sector->lightlevel = flick->minlight;

   else

flick->sector->lightlevel = flick->maxlight - amount;

   flick->count = 4;

} </source>

And this is the function that spawns it at level start.

<source lang="C"> // // P_SpawnFireFlicker // void P_SpawnFireFlicker (sector_t* sector) {

   fireflicker_t*	flick;
   // Note that we are resetting sector attributes.
   // Nothing special about it during gameplay.
   sector->special = 0; 
   flick = Z_Malloc ( sizeof(*flick), PU_LEVSPEC, 0);
   P_AddThinker (&flick->thinker);
   flick->thinker.function.acp1 = (actionf_p1) T_FireFlicker;
   flick->sector = sector;
   flick->maxlight = sector->lightlevel;
   flick->minlight = P_FindMinSurroundingLight(sector,sector->lightlevel)+16;
   flick->count = 4;

} </source>

The light can be seen to flicker to a random value between the sector's light and the minimum surrounding light plus 16 every 4 tics. It does so only in steps of 16 (the minimum amount of difference between two light levels in vanilla Doom).
--Quasar (talk) 19:45, 5 July 2014 (UTC)