Shaders.h

//
//  Created by Bradley Austin Davis on 2018/07/09
//  Copyright 2013-2018 High Fidelity, Inc.
//
//  Distributed under the Apache License, Version 2.0.
//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
//
 
#pragma once
#include <cstdint>
#include <memory>
#include <unordered_map>
#include <unordered_set>
#include <string>
#include <vector>
#include <stdexcept>
 
#include <QtCore/QtGlobal>
 
#include <ShaderEnums.h>
 
namespace shader {
 
static const uint32_t INVALID_SHADER = (uint32_t)-1;
static const uint32_t INVALID_PROGRAM = (uint32_t)-1;
 
const std::vector<uint32_t>& startupPrograms();
const std::vector<uint32_t>& allShaders();
 
enum class Dialect {
    glsl450,
    glsl410,
    glsl310es,
};
 
const std::vector<Dialect>& allDialects();
const std::string& dialectPath(Dialect dialect);
 
enum class Variant {
    Mono,
    Stereo,
};
 
const std::vector<Variant>& allVariants();
 
static const uint32_t NUM_VARIANTS = 2;
 
using Binary = std::vector<uint8_t>;
using String = std::string;
 
struct EnumClassHash
{
    template <typename T>
    std::size_t operator()(T t) const
    {
        return static_cast<std::size_t>(t);
    }
};
 
struct Reflection {
    using LocationMap = std::unordered_map<std::string, int32_t>;
    using ValidSet = std::unordered_set<int32_t>;
 
    void parse(const std::string& json);
    void merge(const Reflection& reflection);
 
    bool validInput(int32_t location) const { return validLocation(validInputs, location); }
    bool validOutput(int32_t location) const { return validLocation(validOutputs, location); }
    bool validTexture(int32_t location) const { return validLocation(validTextures, location); }
    bool validUniform(int32_t location) const { return validLocation(validUniforms, location); }
    bool validUniformBuffer(int32_t location) const { return validLocation(validUniformBuffers, location); }
    bool validResourceBuffer(int32_t location) const { return validLocation(validResourceBuffers, location); }
 
 
    LocationMap inputs;
 
    LocationMap outputs;
 
    LocationMap textures;
 
    LocationMap uniformBuffers;
 
    // Either SSBOs or Textures with the type samplerBuffer, depending on dialect
    LocationMap resourceBuffers;
 
    // Needed for procedural code, will map to push constants for Vulkan
    LocationMap uniforms;
 
    size_t descriptorCount() const {
        return textures.size() + uniformBuffers.size() + resourceBuffers.size();
    }
 
    static std::vector<std::string> getNames(const LocationMap& locations);
 
private:
 
    bool validLocation(const ValidSet& locations, int32_t location) const {
        return locations.contains(location);
    }
 
    void updateValid();
 
    ValidSet validInputs;
    ValidSet validOutputs;
    ValidSet validTextures;
    ValidSet validUniformBuffers;
    ValidSet validResourceBuffers;
    ValidSet validUniforms;
};
 
struct DialectVariantSource {
    // The output of the scribe application with platforms specific headers
    String scribe;
    // Optimized SPIRV version of the shader
    Binary spirv;
    // Regenerated GLSL from the optimized SPIRV
    String glsl;
    // Shader reflection from the optimized SPIRV
    Reflection reflection;
 
    bool valid() const { return !scribe.empty(); }
};
 
struct DialectSource {
    std::unordered_map<Variant, DialectVariantSource, EnumClassHash> variantSources;
};
 
struct Source {
    using Pointer = std::shared_ptr<Source>;
    Source() = default;
    Source& operator=(const Source& other);
 
    uint32_t id{ INVALID_SHADER };
 
    // The name of the shader file, with extension, i.e. DrawColor.frag
    std::string name;
 
    // Generic reflection, copied from the 450 dialect / mono variant
    Reflection reflection;
 
    // Map of platforms to their specific shaders
    std::unordered_map<Dialect, DialectSource, EnumClassHash> dialectSources;
 
    // Support for swapping out code blocks for procedural and debugging shaders
    std::unordered_map<std::string, std::string> replacements;
 
    String getSource(Dialect dialect, Variant variant) const;
    const Reflection& getReflection(Dialect dialect, Variant variant) const;
    bool valid() const { return !dialectSources.empty(); }
    static Source generate(const std::string& glsl) { throw std::runtime_error("Implement me"); }
    static const Source& get(uint32_t shaderId);
 
private:
    // Disallow copy construction
    Source(const Source& other) = delete;
 
    static Source::Pointer loadSource(uint32_t shaderId) ;
 
    bool doReplacement(String& source) const;
    const DialectVariantSource& getDialectVariantSource(Dialect dialect, Variant variant) const;
 
};
 
inline uint32_t getVertexId(uint32_t programId) {
    return (programId >> 16) & UINT16_MAX;
}
 
inline uint32_t getFragmentId(uint32_t programId) {
    return programId & UINT16_MAX;
}
 
inline uint32_t makeProgramId(uint32_t vertexId, uint32_t fragmentId) {
    return (vertexId << 16) | fragmentId;
}
 
}  // namespace shader