OpenHarmony/third_party_mesa3d
2
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

compiler: Add SYSTEM_VALUE_FIRST_VERTEX and instrinsics

Browse Source 
This VS system value will contain the value passed as <basevertex> for
indexed draw calls or the value passed as <first> for non-indexed draw
calls. It can be used to calculate the gl_VertexID as
SYSTEM_VALUE_VERTEX_ID_ZERO_BASE plus SYSTEM_VALUE_FIRST_VERTEX.

From the OpenGL 4.6 spec, 10.4 "Drawing Commands Using Vertex Arrays":

-  Page 352:
"The index of any element transferred to the GL by DrawArraysOneInstance
is referred to as its vertex ID, and may be read by a vertex shader as
gl_VertexID.  The vertex ID of the ith element transferred is first +
i."

- Page 355:
"The index of any element transferred to the GL by
DrawElementsOneInstance is referred to as its vertex ID, and may be read
by a vertex shader as gl_VertexID.  The vertex ID of the ith element
transferred is the sum of basevertex and the value stored in the
currently bound element array buffer at offset indices + i."

Currently the gl_VertexID calculation uses SYSTEM_VALUE_BASE_VERTEX but
this will have to change when the value of gl_BaseVertex is
fixed. Currently its value is broken for non-indexed draw calls because
it must be zero but we are setting it to <first>.

v2: use SYSTEM_VALUE_FIRST_VERTEX as name for the value, instead of
SYSTEM_VALUE_BASE_VERTEX_ID (Kenneth).

v3 (idr): Rebase on Rob Clark converting nir_intrinsics.h to be
generated.  Reformat commit message to 72 columns.

Reviewed-by: Neil Roberts <nroberts@igalia.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Antia Puentes
2018-01-25 19:15:38 +01:00
committed by Ian Romanick
parent 051fddb4a9
commit 5ff848df7b
5 changed files with 21 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
src/compiler/shader_enums.h
View File

@@ -503,6 +503,20 @@ typedef enum
*/
SYSTEM_VALUE_BASE_VERTEX,
/**
* Depending on the type of the draw call (indexed or non-indexed),
* is the value of \c basevertex passed to \c glDrawElementsBaseVertex and
* similar, or is the value of \c first passed to \c glDrawArrays and
* similar.
*
* \note
* It can be used to calculate the \c SYSTEM_VALUE_VERTEX_ID as
* \c SYSTEM_VALUE_VERTEX_ID_ZERO_BASE plus \c SYSTEM_VALUE_FIRST_VERTEX.
*
* \sa SYSTEM_VALUE_VERTEX_ID_ZERO_BASE, SYSTEM_VALUE_VERTEX_ID
*/
SYSTEM_VALUE_FIRST_VERTEX,
/**
* Value of \c baseinstance passed to instanced draw entry points
*