mesh.hpp

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#pragma once
 
#include <filesystem>
#include <optional>
#include <wren/math/matrix.hpp>
#include <wren/mesh.hpp>
#include <wren/mesh_loader.hpp>
 
#include "wren/context.hpp"
 
namespace wren::scene::components {
 
class MeshRenderer {
 public:
  auto bind(const std::shared_ptr<Context>& ctx,
            const std::shared_ptr<vk::Shader>& shader,
            const ::vk::CommandBuffer& cmd, const math::Mat4f& model_mat) {
    if (!mesh_.has_value()) return;
    if (!mesh_->loaded())
      mesh_->load(ctx->graphics_context->Device(),
                  ctx->graphics_context->allocator());
 
    struct LOCALS {
      wren::math::Mat4f model;
      wren::math::Vec4f colour;
    };
    LOCALS ubo{};
 
    ubo.model = model_mat;
    ubo.colour = colour_;
 
    // Load UBO if not there
    if (ubo_ == nullptr) {
      ubo_ = vk::Buffer::create(
          ctx->graphics_context->allocator(), sizeof(ubo),
          VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT,
          VmaAllocationCreateFlagBits::
              VMA_ALLOCATION_CREATE_HOST_ACCESS_SEQUENTIAL_WRITE_BIT);
    }
 
    ubo_->set_data_raw(&ubo, sizeof(LOCALS));
 
    ::vk::DescriptorBufferInfo buffer_info(ubo_->get(), 0, sizeof(LOCALS));
    std::array writes = {::vk::WriteDescriptorSet{
        {}, 1, 0, ::vk::DescriptorType::eUniformBuffer, {}, buffer_info}};
 
    cmd.pushDescriptorSetKHR(::vk::PipelineBindPoint::eGraphics,
                             shader->pipeline_layout(), 0, writes);
 
    mesh_->bind(cmd);
    mesh_->draw(cmd);
  }
 
  auto update_mesh(const Mesh& mesh) { mesh_ = mesh; }
 
  auto update_mesh(const std::filesystem::path& project_root,
                   const std::filesystem::path& mesh_path) -> expected<void> {
    mesh_file_ = mesh_path;
 
    TRY_RESULT(mesh_, load_mesh(project_root / mesh_path));
 
    return {};
  }
 
  void colour(const math::Vec4f& colour) { colour_ = colour; }
 
  [[nodiscard]] auto mesh() const { return mesh_; }
  [[nodiscard]] auto mesh_file() const { return mesh_file_; }
 
 private:
  std::optional<Mesh> mesh_;
 
  wren::math::Vec4f colour_;
 
  std::filesystem::path mesh_file_;
  std::shared_ptr<vk::Buffer> ubo_;
};
 
}  // namespace wren::scene::components