ShaderWriter
This library is used to write shaders directly from C++ code.
It is split in two main libraries (ShaderAST and ShaderWriter) and a "compiler" library for each front end language (CompilerGLSL, CompilerHLSL and CompilerSpirV).
ShaderAST holds the base architecture (expressions and statements, roughly) used to describe a shader.
ShaderWriter is based on ShaderAST, and is fully typed, to be able to write GLSL-like shaders in C++.
The compiler libraries allow exporting the generated AST in either of these shader languages.
How to build
Using packages repositories
You can find shaderwriter on several packages repositories:
- ArchLinux's AUR (thanks to Arthapz)
- xmake-repo (thanks to WubiCookie)
- vcpkg
Using cmake
The following command line should be a good start to build ShaderWriter:
cmake <shaderwriter_root> -DCMAKE_BUILD_TYPE=ReleaseBy default, all libraries (ShaderAST, ShaderWriter and all compilers) will be built as dynamic libraries.
You can use the option -DSDW_BUILD_STATIC=ON to force static build for all of them.
Examples
Let's take the following vertex shader code, written in C++:
template< sdw::var::Flag FlagT >
using PosColStructT = sdw::IOStructInstanceHelperT< FlagT
, "PosCol"
, sdw::IOStructFieldT< sdw::Vec4, "position", 0u >
, sdw::IOStructFieldT< sdw::Vec4, "colour", 1u > >;
template< sdw::var::Flag FlagT >
struct PosColT
: public PosColStructT< FlagT >
{
PosColT( sdw::ShaderWriter & writer
, sdw::expr::ExprPtr expr
, bool enabled = true )
: PosColStructT< FlagT >{ writer, std::move( expr ), enabled }
{
}
auto position()const { return this->getMember< "position" >(); }
auto colour()const { return this->getMember< "colour" >(); }
};
void vertex()
{
using namespace sdw;
VertexWriter writer;
writer.implementMainT< PosColT, PosColT >( [&]( VertexInT< PosColT > in
, VertexOutT< PosColT > out )
{
out.colour() = in.colour();
out.position() = in.position();
out.vtx.position = in.position();
} );
// Select your weapon !
auto glsl = compileGlsl( writer.getShader()
, SpecialisationInfo{}
, glsl::GlslConfig{} );
auto hlsl = compileHlsl( writer.getShader()
, SpecialisationInfo{}
, hlsl::HlslConfig{} );
auto binSpirV = serialiseSpirv( writer.getShader()
, spirv::SpirVConfig{} );
auto textSpirV = writeSpirv( writer.getShader()
, spirv::SpirVConfig{} );
}This shader will generate the following GLSL:
#version 430
layout(location=0) in vec4 sdwIn_position;
layout(location=1) in vec4 sdwIn_colour;
layout(location=0) out vec4 sdwOut_position;
layout(location=1) out vec4 sdwOut_colour;
out gl_PerVertex
{
vec4 gl_Position;
float gl_PointSize;
float gl_ClipDistance[];
float gl_CullDistance[];
};
void main()
{
sdwOut_colour = sdwIn_colour;
sdwOut_position = sdwIn_position;
gl_Position = sdwIn_position;
}The following HLSL (Shader Model 5):
struct HLSL_SDW_GlobalInput
{
float4 colour: TEXCOORD1;
float4 position: TEXCOORD0;
};
struct HLSL_SDW_MainOutput
{
float4 colour: TEXCOORD1;
float4 position: TEXCOORD0;
float4 Position: SV_Position;
};
void main(in HLSL_SDW_GlobalInput sdwGlobalInput
, out HLSL_SDW_MainOutput sdwMainOutput)
{
sdwMainOutput.colour = sdwGlobalInput.colour;
sdwMainOutput.position = sdwGlobalInput.position;
sdwMainOutput.Position = sdwGlobalInput.position;
}And the following SPIR-V listing:
; Magic: 0x07230203
; Version: 0x00010300
; Generator: 0x00210012
; Bound: 18
; Schema: 0
Capability Shader
MemoryModel Logical GLSL450
EntryPoint Vertex %12 "main" %2 %6 %7 %9 %10
; Debug
Source LanguageGLSL 460
Name %2(sdwIn_colour) "sdwIn_colour"
Name %6(sdwIn_position) "sdwIn_position"
Name %7(sdwOut_colour) "sdwOut_colour"
Name %9(sdwOut_position) "sdwOut_position"
Name %10(OutPosition) "OutPosition"
Name %12(main) "main"
; Decorations
Decorate %10(OutPosition) BuiltIn Position
Decorate %7(sdwOut_colour) Location 1
Decorate %2(sdwIn_colour) Location 1
Decorate %9(sdwOut_position) Location 0
Decorate %6(sdwIn_position) Location 0
; Types, Constants, and Global Variables
%3 = TypeFloat 32
%4 = TypeVector %3(f32) 4
%5 = TypePointer Input %4(v4f32)
%2 = Variable %5(InputPtr<v4f32>) Input
%6 = Variable %5(InputPtr<v4f32>) Input
%8 = TypePointer Output %4(v4f32)
%7 = Variable %8(OutputPtr<v4f32>) Output
%9 = Variable %8(OutputPtr<v4f32>) Output
%10 = Variable %8(OutputPtr<v4f32>) Output
%11 = TypeVoid
%13 = TypeFunction %11
; Functions
%12 = Function %11 [None] %13(func)
%14 = Label
%15 = Load %4(v4f32) %2(sdwIn_colour)
Store %7(sdwOut_colour) %15
%16 = Load %4(v4f32) %6(sdwIn_position)
Store %9(sdwOut_position) %16
%17 = Load %4(v4f32) %6(sdwIn_position)
Store %10(OutPosition) %17
Return
FunctionEnd
Some optimisations have been done, but more could be, with SPIR-V (the double load of sdwIn_position, for example, in this case).
Contact
You can reach me on the Discord server dedicated to my projects: DragonJoker's Lair