cpp-danmaku/src/pattern/burstshot_pattern.cxx

//
//  burstshot_pattern.cxx
//  danmaku
//
//  Created by Sam Jaffe on 5/26/19.
//  Copyright © 2019 Sam Jaffe. All rights reserved.
//

#include <json/json.h>
#include <vector>

#include "danmaku/bullet_pattern.hpp"
#include "game/math/angle.hpp"
#include "game/math/common.hpp"
#include "game/math/math_fwd.hpp"
#include "resource_factory/prototype_factory.hpp"
#include "vector/vector.hpp"

using namespace danmaku;

using shot = std::pair<math::vec2, float>;

struct burstshot : public danmaku::bullet_pattern {
  static std::shared_ptr<burstshot> create(danmaku::actor *,
                                           Json::Value const &);

  burstshot(danmaku::actor *, float shot_interval, std::vector<shot> shots);
  void update(float delta) override;

  danmaku::actor * actor;
  danmaku::bullet_timer shot_timer;
  float last_fired{std::numeric_limits<float>::lowest()};
  std::vector<shot> shots;
};

std::vector<shot> shot_vector(std::size_t count, float facing, float covered,
                              float speed, bool clockwise) {
  if (covered == 360.f) { ++count; }
  if (clockwise) { covered = -covered; }

  std::vector<shot> out(count);

  float start = facing + (.5f * covered);
  float end = start - covered;
  if (clockwise != (end < start)) { std::swap(start, end); }

  float const delta = (end - start) / count;
  float current = start;
  for (std::size_t i = 0; i < count; ++i, current += delta) {
    out[i].first = math::rotate({{speed, 0}}, math::degree(current));
    out[i].second = current + 90;
  }
  return out;
}

burstshot::burstshot(danmaku::actor * actor, float shot_interval,
                     std::vector<shot> shots)
    : actor(actor), shot_timer{shot_interval}, shots(shots) {}

std::shared_ptr<burstshot> burstshot::create(danmaku::actor * actor,
                                             Json::Value const & json) {
  return std::make_shared<burstshot>(
      actor, json["timeBetweenBullets"].asFloat(),
      shot_vector(json["bulletsPerWave"].asUInt(),
                  json["centerAngle"].asFloat(), json["burstAngle"].asFloat(),
                  json["bulletSpeed"].asFloat(), json["clockwise"].asBool()));
}

void burstshot::update(float delta) {}

namespace danmaku {
  BIND_BULLET_PATTERN("burstshot", &burstshot::create);
}