CDAG/Research/scene/Material/BitsMaterial.h

#pragma once

#include "../../core/BitHelper.h"
#include "../../core/Defines.h"
#include <cmath>

template <unsigned N>
class BitsMaterial
{
public:
	const static size_t BYTECOUNT = N / 8 + ((N % 8) == 0 ? 0 : 1);  // Calculate the space needed to store the required number of bits
	const static unsigned8 BITS = N;
private:
	unsigned8 mValue[BYTECOUNT];

	static size_t GrabBits(size_t value, unsigned8 startBit, unsigned8 length) {
		return ((BitHelper::GetLSMask<size_t>(startBit, startBit + length)) & value) >> startBit;
	}
	static size_t GrabBits(size_t value, unsigned8 startBit) { return GrabBits(value, startBit, N); }

	inline void Init(size_t value)
	{
		for (unsigned8 i = 0; i < BYTECOUNT; i++)
			mValue[BYTECOUNT - i - 1] = (unsigned8)GrabBits(value, i * 8, 8);
	}
public:
	BitsMaterial() { mValue[0] = 0; }
	BitsMaterial(size_t value) { Init(value); }
	// Grab some bits from the number and store them in this material
	BitsMaterial(unsigned value, unsigned8 startBit) { Init(GrabBits(value, startBit)); }
	~BitsMaterial() {}

	bool Empty() { return mValue == 0; }

	glm::u16vec3 GetProperties() const {
		unsigned32 value = (unsigned32)GetValue();
		return glm::u16vec3(GrabBits(value, 21, 11), GrabBits(value, 10, 11), GrabBits(value, 0, 10));
	}
	void SetProperties(glm::u16vec3 material)
	{
		unsigned32 value = (((unsigned32)material.x) << 21) | (((unsigned32)material.y & BitHelper::GetLSMask<unsigned32>(0, 11)) << 10) | (((unsigned32)material.z) & BitHelper::GetLSMask<unsigned32>(0, 10));
		Init(value);
	}

	size_t GetValue() const {
		size_t value = 0;
		for (unsigned8 i = 0; i < BYTECOUNT; i++)
			value |= mValue[i] << ((BYTECOUNT - i - 1) >> 3); // Get the value, shift it to the correct position, and add it to the GetValue() result
		return value;
	}

	std::string	GetTypeSuffix() const {
		return "b" + std::to_string(N);
	}

	static float Distance(BitsMaterial a, BitsMaterial b)
	{
		size_t maxValue = BitHelper::Exp2(N);
		return (float)std::abs((float)b.GetValue() - (float)a.GetValue()) / (float)maxValue;
	}

	static BitsMaterial Average(const std::vector<BitsMaterial>& values)
	{
		size_t sum = 0;
		for (auto value : values) sum += value.GetValue();
		sum /= values.size();
		return BitsMaterial(sum);
	}

	static BitsMaterial WeightedAverage(const std::vector<BitsMaterial>& values, std::vector<float> weights)
	{
		float sum = 0;
		for (size_t i = 0; i < values.size(); i++) sum += (float)values[i].GetValue() * weights[i];
		sum /= (float)CollectionHelper::Sum(weights);
		return BitsMaterial((size_t)sum);
	}


	void SetLS(size_t index, bool value)
	{
		size_t byte = index >> 8;
		unsigned8 mask = BitHelper::GetLSSingleBitMask<unsigned8>(index & 0x07);
		// Clear the bit
		mValue[byte] &= ~mask;
		// Set the bit
		if (value) mValue[byte] |= mask;
	}

	bool GetLS(size_t index)
	{
		size_t byte = index >> 8;
		size_t bit = index % 8;
		return BitHelper::GetLS(mValue[byte], (unsigned8)bit);
	}

	void SetHS(size_t index, bool value)
	{
		SetLS(N - index - 1, value);
	}

	bool GetHS(size_t index)
	{
		return GetLS(N - index - 1);
	}

	std::vector<unsigned8> Serialize() const {
		std::vector<unsigned8> res(BYTECOUNT);
		for (size_t i = 0; i < BYTECOUNT; i++) res[i] = mValue[i];
		return res;
	}

	void Deserialize(std::vector<unsigned8> value) {
		assert(value.size() == BYTECOUNT);
		for (size_t i = 0; i < BYTECOUNT; i++) mValue[i] = value[i];
	}

	void Serialize(std::ostream& stream) const {
		stream.write((char*)&mValue[0], BYTECOUNT);
	}
	void Deserialize(std::istream& stream) {
		stream.read((char*)&mValue[0], BYTECOUNT);
	}

	bool operator==(const BitsMaterial<N>& other) const {
		for (unsigned i = 0; i < BYTECOUNT; i++)
			if (mValue[i] != other.mValue[i]) return false;
		return true;
	}

	bool operator<(const BitsMaterial<N>& other) const
	{
		for (unsigned8 i = 0; i < BYTECOUNT; i++)
			if (mValue[i] != other.mValue[i]) return mValue[i] < other.mValue[i];
		return false; // If they are equal, return false
	}

	operator unsigned() const
	{
		return (unsigned32)GetValue();
	}
};

namespace std
{
	template<unsigned N> struct hash <BitsMaterial<N>>
	{
		size_t operator()(BitsMaterial<N> const& value) const
		{
			// Check if a perfect hash is possible
			if (N < (sizeof(size_t) * 8))
			{
				return value.GetValue();
			}
			else
			{
				// TODO: make a hash for all bytes
				return value.GetValue();
			}
		}
	};
}

template<unsigned N>
struct BitsMaterialComparer
{
	bool operator()(const BitsMaterial<N>& a, const BitsMaterial<N>& b)
	{
		return a.GetValue() < b.GetValue();
	}
};