User's Manual

User Guide for Chrome 500 Series Graphics
SG195-A.1 10/20/2008
Page 114
3D object’s value on the Z (depth) axis. S3 Graphics
software decides whether to make certain components
of an image visible or hidden to the viewer, based on
values in the Z-buffer.
The stencil buffer holds additional information for each
pixel about whether or not to draw it. Stencils can be of
any shape and can be thought of as a mask with cutouts
that allow an image to be seen through the cutout.
Stenciling is particularly useful in creating special
volumetric effects such as shadow volumes from
multiple light sources. The stencil buffer must interact
closely with the Z buffer.
Hardware assist speeds the clearing of the Z and Stencil
buffers for more efficient rendering.
Setting options include:
Auto (default) – Select Auto to allow S3 Graphics
software to own the decision whether it is
appropriate to use hardware assisted fast clearing of
the Z and/or Stencil buffers. Usually Fast Z clear is
enabled (ON).
ON – Select ON to force Fast Z clear to always ON,
so that all requests to clear the Z and Stencil buffers
will always be processed through hardware. This will
usually speed rendering, and is the preferred setting.
OFF – Select OFF to disable hardware Fast Z clear
and to force clearing of the Z and Stencil buffers
using traditional methods. This will result in a slower
clearing cycle, but may resolve unexpected visual
quality issues. If you suspect an application has
quality issues with Fast Clear, then you may try
disabling this feature to see if it improves visual
quality for that specific application.
Detail level adjust
The number of levels or steps available for use between
the largest and the smallest MIP map image can be
specified by applications and driver software. Called the
MIP map Level of Detail (LOD) bias, settings are
selectable and can produce results ranging from high
speed performance to high visual quality.
“MIP mapping” is actually an abbreviation for the Latin
phrase Multum im Parvum, which means “many in less.”
MIP mapping textures will increase quality and detail by
generating and storing scaled versions of a texture
image. When the texture is rendered in a 3D scene, MIP