ShaderBuilder.cpp

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#include "ShaderBuilder.hpp"
 
#include <format>
#include <fstream>
#include <sstream>
 
namespace sKit {
namespace SDL {
 
auto ShaderBuilder::path(std::string path) noexcept -> ShaderBuilder& {
  path_ = path;
  return *this;
}
 
auto ShaderBuilder::vertex() noexcept -> ShaderBuilder& {
  stage_ = SDL_GPU_SHADERSTAGE_VERTEX;
  return *this;
}
 
auto ShaderBuilder::fragment() noexcept -> ShaderBuilder& {
  stage_ = SDL_GPU_SHADERSTAGE_FRAGMENT;
  return *this;
}
 
auto ShaderBuilder::numUniformBuffers(uint32_t n) noexcept -> ShaderBuilder& {
  numUniformBuffers_ = n;
  return *this;
}
 
auto ShaderBuilder::build(SDL_GPUDevice* device) -> SDL_GPUShader* {
  std::ifstream f(path_);
  if (!f) {
    throw std::runtime_error(std::format("Could not find shader {}", path_));
  }
  std::stringstream buffer;
  buffer << f.rdbuf();
  std::string code = buffer.str();
  SDL_GPUShaderCreateInfo info {
      .code_size = code.size(),
      .code = reinterpret_cast<unsigned char*>(code.data()),
      .entrypoint = "main",
      .format = SDL_GPU_SHADERFORMAT_SPIRV,
      .stage = stage_,
      .num_uniform_buffers = numUniformBuffers_
  };
  if (auto shader = SDL_CreateGPUShader(device, &info)) {
    return shader;
  } else {
    throw std::runtime_error(SDL_GetError());
  }
}
 
}  // namespace SDL
}  // namespace sKit