NAME

DoSampleFilter − Create a supersampling filter camera attribute object for antialiasing

SYNOPSIS

C:

DtObject DoSampleFilter(filter, xwidth, ywidth)
DtObject filter;
DtReal xwidth;
DtReal ywidth;

FORTRAN:

INTEGER∗4 DOSFLT(FILTER, XWIDTH, YWIDTH)
INTEGER∗4 FILTER
REAL∗8 XWIDTH
REAL∗8 YWIDTH

DESCRIPTION

DoSampleFilter creates a supersampling filter camera attribute object for antialiasing.  DoSampleFilter is used in conjunction with DoSampleSuper. 

Supersampling means that each pixel of an image is subdivided into subpixels, and a shade is computed for each of the subpixels.  A filter is then applied to the shades of the subpixels to obtain the final pixel value. 

The computed pixel value is a weighted average of the subpixel shades, typically with higher weights for subpixels closer to the pixel center.  The parameter filter specifies which filter function to use.  Possible values for filter are:

DcFilterBox <DCFBOX>
A box filter function is used. All subpixels under the filter footprint have equal weights.

The parameters xwidth and ywidth specify the size of the filter footprint in output pixels.  For example, if xwidth and ywidth are both 1.0 then the filter footprint covers all the subpixels of a pixel.  If xwidth and/or ywidth are larger than 1.0 then the filters will overlap. 

DEFAULTS

The default DoSampleFilter is (DcFilterBox, 1., 1.). 

SEE ALSO

DoSampleSuper(3D), DoSampleSuperSwitch(3D)

September 02, 1992