1 files changed, 38 insertions, 3 deletions
diff --git a/src/gallium/docs/source/cso/velems.rst b/src/gallium/docs/source/cso/velems.rst
index 92cde014fb..978ad4a243 100644
--- a/src/gallium/docs/source/cso/velems.rst
+++ b/src/gallium/docs/source/cso/velems.rst
@@ -3,9 +3,44 @@
 Vertex Elements
 ===============
 
-This state controls format etc. of the input attributes contained
-in the pipe_vertex_buffer(s). There's one pipe_vertex_element array member
-for each input attribute.
+This state controls the format of the input attributes contained in
+pipe_vertex_buffers. There is one pipe_vertex_element array member for each
+input attribute.
+
+Input Formats
+-------------
+
+Gallium supports a diverse range of formats for vertex data. Drivers are
+guaranteed to support 32-bit floating-point vectors of one to four components.
+Additionally, they may support the following formats:
+
+* Integers, signed or unsigned, normalized or non-normalized, 8, 16, or 32
+  bits wide
+* Floating-point, 16, 32, or 64 bits wide
+
+At this time, support for varied vertex data formats is limited by driver
+deficiencies. It is planned to support a single uniform set of formats for all
+Gallium drivers at some point.
+
+Rather than attempt to specify every small nuance of behavior, Gallium uses a
+very simple set of rules for padding out unspecified components. If an input
+uses less than four components, it will be padded out with the constant vector
+``(0, 0, 0, 1)``.
+
+Fog, point size, the facing bit, and edgeflags, all are in the standard format
+of ``(x, 0, 0, 1)``, and so only the first component of those inputs is used.
+
+Position
+%%%%%%%%
+
+Vertex position may be specified with two to four components. Using less than
+two components is not allowed.
+
+Colors
+%%%%%%
+
+Colors, both front- and back-facing, may omit the alpha component, only using
+three components. Using less than three components is not allowed.
 
 Members
 -------