flower/source/engine/saba/Model/MMD/VMDAnimationCommon.h

//
// Copyright(c) 2016-2019 benikabocha.
// Distributed under the MIT License (http://opensource.org/licenses/MIT)
//

#ifndef SABA_MODEL_MMD_VMDANIMATIONCOMMON_H_
#define SABA_MODEL_MMD_VMDANIMATIONCOMMON_H_

#include <cstdint>
#include <vector>

namespace saba
{
	template <typename KeyType>
	typename std::vector<KeyType>::const_iterator FindBoundKey(
		const std::vector<KeyType>&	keys,
		int32_t						t,
		size_t						startIdx
	) {
		if (keys.empty() || keys.size() <= startIdx)
		{
			return keys.end();
		}

		const auto& key0 = keys[startIdx];
		if (key0.m_time <= t)
		{
			if (startIdx + 1 < keys.size())
			{
				const auto& key1 = keys[startIdx + 1];
				if (key1.m_time > t)
				{
					return keys.begin() + startIdx + 1;
				}
			}
			else
			{
				return keys.end();
			}
		}
		else
		{
			if (startIdx != 0)
			{
				const auto& key1 = keys[startIdx - 1];
				if (key1.m_time <= t)
				{
					return keys.begin() + startIdx;
				}
			}
			else
			{
				return keys.begin();
			}
		}

		auto bundIt = std::upper_bound(keys.begin(), keys.end(), t, [](int32_t lhs, const KeyType& rhs) {
			return lhs < rhs.m_time;
		});
		return bundIt;
	}
}

#endif // !SABA_MODEL_MMD_VMDANIMATIONCOMMON_H_