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Diffstat (limited to 'src/gallium/docs/source/tgsi.rst')
| -rw-r--r-- | src/gallium/docs/source/tgsi.rst | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst index 4315707..ab12490 100644 --- a/src/gallium/docs/source/tgsi.rst +++ b/src/gallium/docs/source/tgsi.rst @@ -2876,18 +2876,32 @@ annotated with those semantics. TGSI_SEMANTIC_CLIPDIST """""""""""""""""""""" +Note this covers clipping and culling distances. + When components of vertex elements are identified this way, these values are each assumed to be a float32 signed distance to a plane. + +For clip distances: Primitive setup only invokes rasterization on pixels for which -the interpolated plane distances are >= 0. Multiple clip planes -can be implemented simultaneously, by annotating multiple -components of one or more vertex elements with the above specified -semantic. The limits on both clip and cull distances are bound +the interpolated plane distances are >= 0. + +For cull distances: +Primitives will be completely discarded if the plane distance +for all of the vertices in the primitive are < 0. +If a vertex has a cull distance of NaN, that vertex counts as "out" +(as if its < 0); + +Multiple clip/cull planes can be implemented simultaneously, by +annotating multiple components of one or more vertex elements with +the above specified semantic. +The limits on both clip and cull distances are bound by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_COUNT define which defines the maximum number of components that can be used to hold the distances and by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT which specifies the maximum number of registers which can be annotated with those semantics. +The properties NUM_CLIPDIST_ENABLED and NUM_CULLDIST_ENABLED +are used to divide up the 2 x vec4 space between clipping and culling. TGSI_SEMANTIC_SAMPLEID """""""""""""""""""""" |