Tips for Efficient Lighting
Lights are expensive in terms of performance, so they should be used
sparingly. In general, two or three lights per scene is the limit for
acceptable rendering speed. A few other tips:
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Spotlights require the most processing power, point lights require
somewhat less processing power, and directional lights require the
least. Note too that a shape must be finely tessellated in order for
you to see the effects of a spotlight (because lighting is done per
vertex, not per pixel). These extra polygons also slow down rendering.
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Make sure the materials in your scene have a reasonable amount of
emissive color so that objects will still be visible even if lighting
is low.
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One way to simulate sophisticated lighting effects such as spotlights
is to use per-vertex colors on an object (one designer referred to this
as "burning the colors into the shape"). Because the colors
are precalculated, rendering speed is improved. The scene shown here
uses this technique in place of spotlights:
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