So what’s the thing about face lights

Your viewer has a pretty hard job to do. Twenty or so times a second it has to generate a scene, move the objects, apply textures,calculate the lighting to apply to each polygon.  To see how many polygons that is ask your viewer to show wireframe.

There are two different algorithms it can use to apply the lighting to the polygons .  The one it uses in basic mode and the one it uses in advanced mode when advanced lights are used.  The first of these isn’t that efficient and your viewer is only capable of rendering 8 lights in total, two of these are reserved for the sun and the moon, leaving six lights. More than this can cause excessive client side lag.  The advanced algorithm, called deferred rendering is more efficient and can handle more lights, however, there is still a limit and your viewer has to decide how to apply this limit.  Usually this is decided based on the lights seen from your avatars position – not your camera position). if that isn’t enough your viewer must work out how to apply all of this and still end up with a correctly exposed image.

The problem with face lights are:

  • Virtually all of them aren’t using advanced lighting – they are using point lighting
  • They are often over bright and are applied multipully (6 face lights which is pretty common potentially ruin the scene for anyone else who is near), they dominate the scene and screw up the balancing of other light sources by your viewer.
  • They move and turn – this causes other lights to cut in and cut out as your viewer is trying to balance the lighting in the scene, for anyone watching this – this can be a very ugly effect.
  • They overload anyone in basic mode – all they see are the 6 closest face light rather than what all the work went into creating. Even in advanced mode there is an element of this.
  • Changes made to the rendering model some time ago cause basic lights to have a range far greater than that which is set for them so more polygons are included in the calculation to apply the light and other lighting effects can be overwhelmed.  And there is strong evidence to suggest that when your viewer is trying to balance the lighting in a scene it takes into account all lights it knows about, not just the ones it has decided to render (this is so that there aren’t significant exposure changes as the lighting mix changes), this implies that any stray lights and not just face lights can upset this task – for example at TOTH, lights under the stage and even on other stages are still having an effect on rendering on the main stage – this is not insignificant, your computer really has to perform these calculations for millions of polygons every second.
  • All of this adds, and can add seriously, to client side lag
  • They can completely overwhelm and even ruin a scene, especially if it was set up to use subtle effects.
  • The advanced theatre lights will give you effectively a face light better than any you could dream of.

These arguments also apply to basic mode lighting built into sets. None of these lights is ever switchable and, therefore, are always on. They then have all the negative impacts to do with scene rendering and client side lag.  Its best not to have them, if you do have them then make them switchable, lighting under the stage which are turned on have a big negative effect on everyones viewer performance!


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