Graphics Reference
In-Depth Information
(a)
(b)
(c)
(d)
Figure 3.18.
(a) Scene with volumetric light effects and transparent objects. Notice
the dark transparent objects in the background not being properly composited with
the volumetric light. (b) The same scene now using the volume light intensity buffer to
properly blend volumetric light with the transparent objects. (c) A smoke particle effect
not blending properly with the volumetric light effect. (d) Result after using the volume
light intensity buffer to properly blend the smoke with the volumetric light effect.
3.6 Transparent Objects
The way we render our volumetric lights and composite them to the scene causes
problems when rendering transparent objects that use alpha blending (Figure
3.18(a)). Especially alpha-blended particle effects didn't blend properly with the
volumetric lighting effects (Figure 3.18(c)). Depending on the rendering order,
either the volumetric light is drawn in front of all transparent objects, or the
transparent objects occlude the volumetric light effects.
In order to solve this issue, we had to find a way to make the transparent
shaders aware of the existence of the volumetric light. If we know how much
volumetric light is in front of a transparent surface, we can blend the volumetric
light properly with the transparent objects (Figure 3.18(b) and (d)).
