diff options
| author | Neil Roberts <[email protected]> | 2018-04-19 17:17:41 +0200 |
|---|---|---|
| committer | Alejandro Piñeiro <[email protected]> | 2018-08-13 16:23:36 +0200 |
| commit | be6f472b2387f508e55ffbe758da8cbea75717d6 (patch) | |
| tree | 4fc83e75f858a2f6c6f5f04996bf4fbbae637a19 /src/compiler/spirv | |
| parent | 624c00f1a6fd6e09fc5101a735a2c88e098ee675 (diff) | |
spirv: Make VertexIndex and VertexId both non-zero-based
GLSL has gl_VertexID which is supposed to be non-zero-based.
SPIR-V has both VertexIndex and VertexId builtins whose meanings are
defined by the APIs.
Vulkan defines VertexIndex as being non-zero-based. In Vulkan VertexId
and InstanceId have no meaning and are pretty much just reserved for
OpenGL at this point.
GL_ARB_spirv removes VertexIndex and defines VertexId to be the same
as gl_VertexId (which is also non-zero-based).
Previously in Mesa it was treating VertexIndex as non-zero-based and
VertexId as zero-based, so it was breaking for GL. This behaviour was
apparently based on Khronos bug 14255. However that bug doesn’t seem
to have made a final decision for VertexId.
Assuming there really is no other definition for VertexId for Vulkan
it seems better to just make them both have the same value.
v2: update comment and commit descriptions, based on Jason Ekstrand
explanation of the meaning/rationale behind all those builtins
(Jason)
Reviewed-by: Jason Ekstrand <[email protected]>
Diffstat (limited to 'src/compiler/spirv')
| -rw-r--r-- | src/compiler/spirv/vtn_variables.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/src/compiler/spirv/vtn_variables.c b/src/compiler/spirv/vtn_variables.c index 8dab86abd74..571a14cf4cf 100644 --- a/src/compiler/spirv/vtn_variables.c +++ b/src/compiler/spirv/vtn_variables.c @@ -1011,15 +1011,15 @@ vtn_get_builtin_location(struct vtn_builder *b, case SpvBuiltInCullDistance: *location = VARYING_SLOT_CULL_DIST0; break; - case SpvBuiltInVertexIndex: - *location = SYSTEM_VALUE_VERTEX_ID; - set_mode_system_value(b, mode); - break; case SpvBuiltInVertexId: - /* Vulkan defines VertexID to be zero-based and reserves the new - * builtin keyword VertexIndex to indicate the non-zero-based value. + case SpvBuiltInVertexIndex: + /* The Vulkan spec defines VertexIndex to be non-zero-based and doesn't + * allow VertexId. The ARB_gl_spirv spec defines VertexId to be the + * same as gl_VertexID, which is non-zero-based, and removes + * VertexIndex. Since they're both defined to be non-zero-based, we use + * SYSTEM_VALUE_VERTEX_ID for both. */ - *location = SYSTEM_VALUE_VERTEX_ID_ZERO_BASE; + *location = SYSTEM_VALUE_VERTEX_ID; set_mode_system_value(b, mode); break; case SpvBuiltInInstanceIndex: |