Shader Bindings

Most renderer shader resources use shared binding constants across C++ and GLSL.

The system is centered around engine-internal shader binding definitions that generate shared C++ enums and GLSL constants.

Shaders include the generated GLSL bindings header before declaring bound resources.

Some legacy and particle shaders still hard-code numeric bindings. Current examples include Engine/shaders/TrailPrepareDraw.comp, Engine/shaders/ParticleSimulate.comp, and Engine/shaders/TrailUpdate.comp.

Example

C++ defines binding enums through a macro list.

#define SHADER_BINDING_ENUM_NAME( X ) \
    X(ENUM_A, 0) \
    X(ENUM_B, 1)
 
namespace ShaderNamespace
{
    enum Binding : uint32_t
    {
        SHADER_BINDING_ENUM_NAME(BINDING_ENUM_ENTRY)
    };
}

GLSL using the generated bindings header uses BINDING_ constants.

#extension GL_GOOGLE_include_directive : require
 
#include "shader_bindings.glsl.h"
 
// Generated binding names are prefixed by BINDING_
layout(std430, set = 0, binding = BINDING_ENUM_A) readonly buffer BufferA {
    uint value_A;
};
 
layout(std430, set = 0, binding = BINDING_ENUM_B) readonly buffer BufferB {
    uint value_B;
};