From 5ff848df7be34bdc4c2e0ad509ad43b4ae1fc3b9 Mon Sep 17 00:00:00 2001 From: Antia Puentes Date: Thu, 25 Jan 2018 19:15:38 +0100 Subject: compiler: Add SYSTEM_VALUE_FIRST_VERTEX and instrinsics This VS system value will contain the value passed as for indexed draw calls or the value passed as 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 . 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 Reviewed-by: Kenneth Graunke --- src/compiler/nir/nir.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'src/compiler/nir/nir.c') diff --git a/src/compiler/nir/nir.c b/src/compiler/nir/nir.c index ef911540f37..ea28fbd1af5 100644 --- a/src/compiler/nir/nir.c +++ b/src/compiler/nir/nir.c @@ -1991,6 +1991,8 @@ 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: @@ -2066,6 +2068,8 @@ 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: -- cgit v1.2.3