Graphics Reference
In-Depth Information
Figure 4.8. The area of interest between the minimum and maximum depth plane of
the four pixels for which we calculate the visibility; basically, take the percentage of
empty volume.
We cannot rely on only the visibility buffer, though. We must know how much
our cone actually intersects the geometry as well, and for that we will utilize our
Hi-Z buffer. Our final weight will be the accumulated visibility multiplied by how
much our cone sphere is above, in between, or below the Hi-Z buffer.
The format for this pre-integration buffer is an 8 bit per channel texture that
gives 256 values to represent our visibility. This gives 0.390625% of increments for
our visibility values (1.0/256.0), which is good enough precision for transparency.
Again, this pass is highly dependent on whether we have a post-projected
depth Hi-Z or a view-space Hi-Z buffer.
100%
Visibility
100%
Visibility
100%
Visibility
100%
Visibility
50%
Visibility
100%
Visibility
37.5%
Visibility
MIP 0
MIP 1
MIP 2
Figure 4.9. A 2D representation of the hierarchical pre-integrated visibility buffer. The percent is calcu-
lated between the minimum and maximum depths. The height is the depth and the color is the amount
of visibility.
Search WWH ::




Custom Search