References 41
eliminating the lighting calculations from the fragment processor, we’re just left
with finding the first intersection of the view ray with a cloud and terminating the
ray early—we’ve now rendered our cloud volume with an effective depth
complexity close to one!
Volumetric slicing may also benefit from a hybrid approach. For example, a
fragment program may be employed to perform lighting of each fragment using
GPU ray casting, while still relying on the slice geometry to handle compositing
along the view direction.
Other approaches render a cloud as a mesh [Bouthors et al. 2008], again
taking advantage of the low mean free path of cumulus clouds. This allows more
precise lighting and avoids the intersection problems introduced by proxy
geometry in volume rendering.
Ultimately, choosing a cloud rendering technique depends on the trade-offs
you’re willing to make between hardware compatibility, physical realism, and
performance—fortunately, there are a variety of techniques to choose from.
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