[Mesa-dev] [PATCH v4 1/6] compiler: Add SYSTEM_VALUE_FIRST_VERTEX and instrinsics
Ian Romanick
idr at freedesktop.org
Fri Apr 6 21:53:02 UTC 2018
From: Antia Puentes <apuentes at igalia.com>
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 at igalia.com>
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
---
src/compiler/nir/nir.c | 4 ++++
src/compiler/nir/nir_gather_info.c | 1 +
src/compiler/nir/nir_intrinsics.py | 1 +
src/compiler/shader_enums.c | 1 +
src/compiler/shader_enums.h | 14 ++++++++++++++
5 files changed, 21 insertions(+)
diff --git a/src/compiler/nir/nir.c b/src/compiler/nir/nir.c
index 8364197480b..c4933b05c11 100644
--- a/src/compiler/nir/nir.c
+++ b/src/compiler/nir/nir.c
@@ -1988,6 +1988,8 @@ nir_intrinsic_from_system_value(gl_system_value val)
return nir_intrinsic_load_base_instance;
case SYSTEM_VALUE_VERTEX_ID_ZERO_BASE:
return nir_intrinsic_load_vertex_id_zero_base;
+ case SYSTEM_VALUE_FIRST_VERTEX:
+ return nir_intrinsic_load_first_vertex;
case SYSTEM_VALUE_BASE_VERTEX:
return nir_intrinsic_load_base_vertex;
case SYSTEM_VALUE_INVOCATION_ID:
@@ -2063,6 +2065,8 @@ nir_system_value_from_intrinsic(nir_intrinsic_op intrin)
return SYSTEM_VALUE_BASE_INSTANCE;
case nir_intrinsic_load_vertex_id_zero_base:
return SYSTEM_VALUE_VERTEX_ID_ZERO_BASE;
+ case nir_intrinsic_load_first_vertex:
+ return SYSTEM_VALUE_FIRST_VERTEX;
case nir_intrinsic_load_base_vertex:
return SYSTEM_VALUE_BASE_VERTEX;
case nir_intrinsic_load_invocation_id:
diff --git a/src/compiler/nir/nir_gather_info.c b/src/compiler/nir/nir_gather_info.c
index 5530009255d..5e5779ac4b7 100644
--- a/src/compiler/nir/nir_gather_info.c
+++ b/src/compiler/nir/nir_gather_info.c
@@ -265,6 +265,7 @@ gather_intrinsic_info(nir_intrinsic_instr *instr, nir_shader *shader)
case nir_intrinsic_load_vertex_id:
case nir_intrinsic_load_vertex_id_zero_base:
case nir_intrinsic_load_base_vertex:
+ case nir_intrinsic_load_first_vertex:
case nir_intrinsic_load_base_instance:
case nir_intrinsic_load_instance_id:
case nir_intrinsic_load_sample_id:
diff --git a/src/compiler/nir/nir_intrinsics.py b/src/compiler/nir/nir_intrinsics.py
index 1bc99552cd7..f26aaf35ee3 100644
--- a/src/compiler/nir/nir_intrinsics.py
+++ b/src/compiler/nir/nir_intrinsics.py
@@ -413,6 +413,7 @@ system_value("frag_coord", 4)
system_value("front_face", 1)
system_value("vertex_id", 1)
system_value("vertex_id_zero_base", 1)
+system_value("first_vertex", 1)
system_value("base_vertex", 1)
system_value("instance_id", 1)
system_value("base_instance", 1)
diff --git a/src/compiler/shader_enums.c b/src/compiler/shader_enums.c
index d0ff11b41e2..ebee076b43c 100644
--- a/src/compiler/shader_enums.c
+++ b/src/compiler/shader_enums.c
@@ -216,6 +216,7 @@ gl_system_value_name(gl_system_value sysval)
ENUM(SYSTEM_VALUE_INSTANCE_ID),
ENUM(SYSTEM_VALUE_INSTANCE_INDEX),
ENUM(SYSTEM_VALUE_VERTEX_ID_ZERO_BASE),
+ ENUM(SYSTEM_VALUE_FIRST_VERTEX),
ENUM(SYSTEM_VALUE_BASE_VERTEX),
ENUM(SYSTEM_VALUE_BASE_INSTANCE),
ENUM(SYSTEM_VALUE_DRAW_ID),
diff --git a/src/compiler/shader_enums.h b/src/compiler/shader_enums.h
index 2aedbb9b3fa..8a277a14f21 100644
--- a/src/compiler/shader_enums.h
+++ b/src/compiler/shader_enums.h
@@ -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
*
--
2.14.3
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