shader_reflection.hpp

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#pragma once
 
#include <cstdint>
#include <nlohmann/json.hpp>
#include <optional>
#include <slang.h>
#include <string>
#include <toast/export.hpp>
#include <vector>
 
namespace renderer {
 
enum class ShaderMemberType : uint8_t {
  unknown,
  bool_t,
  int_t,
  uint_t,
  float_t,
  vec2,
  vec3,
  vec4,
  mat3,
  mat4,
};
 
enum class ShaderBindingKind : uint8_t {
  uniform_buffer,
  storage_buffer,
  combined_image_sampler,
  sampled_image,
  sampler,
  storage_image,
  acceleration_structure,
};
 
struct ShaderInspectorMeta {
  bool reflected = false;
  std::optional<float> range_min;
  std::optional<float> range_max;
  bool is_color = false;
  std::string display_name;
  std::string group;
  std::string subgroup;
  std::string unit;
  std::string default_fallback;    // "white" "black" or "flat_normal"
  bool linear_data = false;
};
 
struct ShaderBlockMember {
  std::string name;
  ShaderMemberType type = ShaderMemberType::unknown;
  uint32_t offset = 0;
  uint32_t size = 0;
  uint32_t element_count = 0;
  uint32_t element_stride = 0;
  std::string engine_semantic;
  ShaderInspectorMeta inspector;
};
 
struct ShaderBinding {
  uint32_t set = 0;
  uint32_t binding = 0;
  std::string name;
  ShaderBindingKind kind = ShaderBindingKind::uniform_buffer;
  uint32_t count = 1;
  uint32_t size = 0;
  std::vector<ShaderBlockMember> members;
  std::string engine_semantic;    // "frame" for engine reserved set 0
  ShaderInspectorMeta inspector;
};
 
struct ShaderPushConstants {
  std::string name;
  uint32_t size = 0;
  std::vector<ShaderBlockMember> members;
};
 
struct ShaderEntryPoint {
  std::string name;
  std::string stage;    // "vertex" "fragment" or "compute"
};
 
struct ShaderReflection {
  std::vector<ShaderEntryPoint> entry_points;
  std::vector<ShaderBinding> bindings;
  std::vector<ShaderPushConstants> push_constants;
  std::vector<std::string> layout_order;
 
  [[nodiscard]]
  auto TOAST_API toJson() const -> nlohmann::json;
 
  static auto TOAST_API fromJson(const nlohmann::json& json) -> std::optional<ShaderReflection>;
};
 
auto extractReflection(slang::ProgramLayout* layout) -> ShaderReflection;

void extractModuleEntryPoints(slang::IModule* module, ShaderReflection& reflection);
 
auto toString(ShaderMemberType type) -> std::string_view;
auto toString(ShaderBindingKind kind) -> std::string_view;
auto memberTypeFromString(std::string_view str) -> ShaderMemberType;
auto bindingKindFromString(std::string_view str) -> ShaderBindingKind;
 
}