docs: clean up TGSI_SEMANTIC_PSIZE description

there was some confusion between point size state and point size output.

diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst
index ebee490..ef06844 100644 (file)
--- a/src/gallium/docs/source/tgsi.rst
+++ b/src/gallium/docs/source/tgsi.rst
@@ -1231,10 +1231,8 @@ TGSI_SEMANTIC_PSIZE
 """""""""""""""""""
 
 PSIZE, or point size, is used to specify point sizes per-vertex. It should
-be in ``(p, n, x, f)`` format, where ``p`` is the point size, ``n`` is the minimum
-size, ``x`` is the maximum size, and ``f`` is the fade threshold.
-
-XXX this is arb_vp. is this what we actually do? should double-check...
+be in ``(s, 0, 0, 1)`` format, where ``s`` is the (possibly clamped) point size.
+Only the first component matters when writing from the vertex shader.
 
 When using this semantic, be sure to set the appropriate state in the
 :ref:`rasterizer` first.