8.3 KiB
8.3 KiB
Translations
This document attempts to document how WGSL translates into the various backends for the cases where the translation is not a direct mapping.
Access Control
HLSL
- ReadOnly ->
ByteAddressBuffer
- ReadWrite ->
RWByteAddressBuffer
MSL
- ReadOnly ->
const
SPIR-V
There are two ways this can be achieved in SPIR-V. Either the variable can be
decorated with NonWritable
or each member of the struct can be decorated with
NonWritable
. We chose to go the struct member route.
- The read-only becomes part of the type in this case. Otherwise, you are treating the readonly type information as part of the variable which is confusing.
- Treating the readonly as part of the variable means we should be deduplicating the types behind the access control, which causes confusing with the type_names and various tracking systems within Tint.
Builtin Decorations
Name | SPIR-V | MSL | HLSL |
---|---|---|---|
position | SpvBuiltInPosition | position | SV_Position |
vertex_idx | SpvBuiltInVertexIndex | vertex_id | SV_VertexID |
instance_idx | SpvBuiltInInstanceIndex | instance_id | SV_InstanceID |
front_facing | SpvBuiltInFrontFacing | front_facing | SV_IsFrontFacing |
frag_coord | SpvBuiltInFragCoord | position | SV_Position |
frag_depth | SpvBuiltInFragDepth | depth(any) | SV_Depth |
local_invocation_id | SpvBuiltInLocalInvocationId | thread_position_in_threadgroup | SV_GroupThreadID |
local_invocation_idx | SpvBuiltInLocalInvocationIndex | thread_index_in_threadgroup | SV_GroupIndex |
global_invocation_id | SpvBuiltInGlobalInvocationId | thread_position_in_grid | SV_DispatchThreadID |
Builtins Methods
Name | SPIR-V | MSL | HLSL |
---|---|---|---|
abs | GLSLstd450FAbs or GLSLstd450SAbs | fabs or abs | abs |
acos | GLSLstd450Acos | acos | acos |
all | SpvOpAll | all | all |
any | SpvOpAny | any | any |
arrayLength | SpvOpArrayLength | ||
asin | GLSLstd450Asin | asin | asin |
atan | GLSLstd450Atan | atan | atan |
atan2 | GLSLstd450Atan2 | atan2 | atan2 |
ceil | GLSLstd450Ceil | ceil | ceil |
clamp | GLSLstd450NClamp or GLSLstd450UClamp or GLSLstd450SClamp | clamp | clamp |
cos | GLSLstd450Cos | cos | cos |
cosh | GLSLstd450Cosh | cosh | cosh |
countOneBits | SpvOpBitCount | popcount | countbits |
cross | GLSLstd450Cross | cross | cross |
determinant | GLSLstd450Determinant | determinant | determinant |
distance | GLSLstd450Distance | distance | distance |
dot | SpOpDot | dot | dot |
dpdx | SpvOpDPdx | dpdx | ddx |
dpdxCoarse | SpvOpDPdxCoarse | dpdx | ddx_coarse |
dpdxFine | SpvOpDPdxFine | dpdx | ddx_fine |
dpdy | SpvOpDPdy | dpdy | ddy |
dpdyCoarse | SpvOpDPdyCoarse | dpdy | ddy_coarse |
dpdyFine | SpvOpDPdyFine | dpdy | ddy_fine |
exp | GLSLstd450Exp | exp | exp |
exp2 | GLSLstd450Exp2 | exp2 | exp2 |
faceForward | GLSLstd450FaceForward | faceforward | faceforward |
floor | GLSLstd450Floor | floor | floor |
fma | GLSLstd450Fma | fma | fma |
fract | GLSLstd450Fract | fract | frac |
frexp | GLSLstd450Frexp | ||
fwidth | SpvOpFwidth | fwidth | fwidth |
fwidthCoarse | SpvOpFwidthCoarse | fwidth | fwidth |
fwidthFine | SpvOpFwidthFine | fwidth | fwidth |
inverseSqrt | GLSLstd450InverseSqrt | rsqrt | rsqrt |
isFinite | isfinite | isfinite | |
isInf | SpvOpIsInf | isinf | isinf |
isNan | SpvOpIsNan | isnan | isnan |
isNormal | isnormal | ||
ldexp | GLSLstd450Ldexp | ||
length | GLSLstd450Length | length | length |
log | GLSLstd450Log | log | log |
log2 | GLSLstd450Log2 | log2 | log2 |
max | GLSLstd450NMax or GLSLstd450SMax or GLSLstd450UMax | fmax or max | max |
min | GLSLstd450NMin or GLSLstd450SMin or GLSLstd450UMin | fmin or min | min |
mix | GLSLstd450FMix | mix | mix |
modf | GLSLstd450Modf | ||
normalize | GLSLstd450Normalize | normalize | normalize |
pow | GLSLstd450Pow | pow | pow |
reflect | GLSLstd450Reflect | reflect | reflect |
reverseBits | SpvOpBitReverse | reverse_bits | reversebits |
round | GLSLstd450Round | round | round |
select | SpvOpSelect | select | |
sign | GLSLstd450FSign | sign | sign |
sin | GLSLstd450Sin | sin | sin |
sinh | GLSLstd450Sinh | sinh | sinh |
smoothStep | GLSLstd450SmoothStep | smoothstep | smoothstep |
sqrt | GLSLstd450Sqrt | sqrt | sqrt |
step | GLSLstd450Step | step | step |
tan | GLSLstd450Tan | tan | tan |
tanh | GLSLstd450Tanh | tanh | tanh |
trunc | GLSLstd450Trunc | trunc | trunc |
Types
Sampler Types
WGSL | SPIR-V | MSL | HLSL |
---|---|---|---|
sampler | OpTypeSampler | sampler | SamplerState |
sampler_comparison | OpTypeSampler | sampler | SamplerComparisonState |
Texture Types
WGSL | SPIR-V | MSL | HLSL |
---|---|---|---|
texture_1d<type> | OpTypeImage 1D Sampled=1 | texture1d<type, access::sample> | Texture1D |
texture_1d_array<type> | OpTypeImage 1D Arrayed=1 Sampled=1 | texture1d_array<type, access::sample> | Texture1DArray |
texture_2d<type> | OpTypeImage 2D Sampled=1 | texture2d<type, access::sample> | Texture2D |
texture_2d_array<type> | OpTypeImage 2D Arrayed=1 Sampled=1 | texture2d_array<type, access::sample> | Texture2DArray |
texture_3d<type> | OpTypeImage 3D Sampled=1 | texture3d<type, access::sample> | Texture3D |
texture_cube<type> | OpTypeImage Cube Sampled=1 | texturecube<type, access::sample> | TextureCube |
texture_cube_array<type> | OpTypeImage Cube Arrayed=1 Sampled=1 | texturecube_array<type, access::sample> | TextureCubeArray |
texture_multisampled_2d<type> | OpTypeImage 2D MS=1 Sampled=1 | texture2d_ms<type, access::sample> | Texture2D |
texture_depth_2d | OpTypeImage 2D Depth=1 Sampled=1 | depth2d<float, access::sample> | Texture2D |
texture_depth_2d_array | OpTypeImage 2D Depth=1 Arrayed=1 Sampled=1 | depth2d_array<float, access::sample> | Texture2DArray |
texture_depth_cube | OpTypeImage Cube Depth=1 Sampled=1 | depthcube<float, access::sample> | TextureCube |
texture_depth_cube_array | OpTypeImage Cube Depth=1 Arrayed=1 Sampled=1 | depthcube_array<float, access::sample> | TextureCubeArray |
texture_storage_ro_1d<image_storage_type> | OpTypeImage 1D Sampled=2 | texture1d<type, access::read> | RWTexture1D |
texture_storage_ro_1d_array<image_storage_type> | OpTypeImage 1D Arrayed=1 Sampled=2 | texture1d_array<type, access::read> | RWTexture1DArray |
texture_storage_ro_2d<image_storage_type> | OpTypeImage 2D Sampled=2 | texture2d<type, access::read> | RWTexture2D |
texture_storage_ro_2d_array<image_storage_type> | OpTypeImage 2D Arrayed=1 Sampled=2 | texture2d_array<type, access::read> | RWTexture2DArray |
texture_storage_ro_3d<image_storage_type> | OpTypeImage 3D Sampled=2 | texture3d<type, access::read> | RWTexture3D |
texture_storage_wo_1d<image_storage_type> | OpTypeImage 1D Sampled=2 | texture1d<type, access::write> | RWTexture1D |
texture_storage_wo_1d_array<image_storage_type> | OpTypeImage 1D Arrayed=1 Sampled=2 | texture1d_array<type, access::write> | RWTexture1DArray |
texture_storage_wo_2d<image_storage_type> | OpTypeImage 2D Sampled=1 | texture2d<type, access::write> | RWTexture2D |
texture_storage_wo_2d_array<image_storage_type> | OpTypeImage 2D Arrayed=1 Sampled=2 | texture2d_array<type, access::write> | RWTexture2DArray |
texture_storage_wo_3d<image_storage_type> | OpTypeImage 3D Sampled=2 | texture3d<type, access::write> | RWTexture3D |
Short-circuting
HLSL
TODO(dsinclair): Nested if's
SPIR-V
TODO(dsinclair): Nested if's
Storage classes
TODO(dsinclair): do ...
Storage buffers
HLSL
TODO(dsinclair): Rewriting of accessors to loads
Loop blocks
HLSL
TODO(dsinclair): Rewrite with bools
MSL
TODO(dsinclair): Rewrite with bools
Input / Output storage class
HLSL
TODO(dsinclair): Structs and params
MSL
TODO(dsinclair): Structs and params
Discard
HLSL
discard
MSL
discard_fragment()
Specialization constants
HLSL
#ifndef WGSL_SPEC_CONSTANT_<id>
-- if default provided
#define WGSL_SPEC_CONSTANT_<id> default value
-- else
#error spec constant required for constant id
--
#endif
static const <type> <name> = WGSL_SPEC_CONSTANT_<id>
MSL
[[function_constant(<id>)]]