还是关于阴影的文档资料。nvidia--关于使用hlsl语言的。-Shadows are an important visual cue.　Unfortunately, most real-time techniques f

computing shadows generate hard and, in the case of shadow-maps, aliased

shadows.　We can soften the edges of the shadows by employing percentage-clos

filtering.　In fact, a sufficiently large percentage-closer filter approximates soft

shadow boundaries well.　High quality soft shadows, however, require a large

number of samples.