src/base/math.h - master - dieoska/ddnet

src/base/math.h
173 строки3 KB
KebsCS
Add constexpr and concepts to math functions
02 июл 2025, 21:15
02 июл 2025, 21:15bc96416
/* (c) Magnus Auvinen. See licence.txt in the root of the distribution for more information. */
/* If you are missing that file, acquire a complete release at teeworlds.com.                */
#ifndef BASE_MATH_H
#define BASE_MATH_H

#include <algorithm>
#include <cmath>
#include <concepts>
#include <cstdlib>

template<typename T>
concept Numeric = std::integral<T> || std::floating_point<T>;

constexpr float pi = 3.1415926535897932384626433f;

constexpr int round_to_int(float f)
{
	return f > 0 ? (int)(f + 0.5f) : (int)(f - 0.5f);
}

constexpr int round_truncate(float f)
{
	return (int)f;
}

template<typename T, typename TB>
constexpr T mix(const T a, const T b, TB amount)
{
	return a + (b - a) * amount;
}

template<typename T, typename TB>
constexpr T bezier(const T p0, const T p1, const T p2, const T p3, TB amount)
{
	// De-Casteljau Algorithm
	const T c10 = mix(p0, p1, amount);
	const T c11 = mix(p1, p2, amount);
	const T c12 = mix(p2, p3, amount);

	const T c20 = mix(c10, c11, amount);
	const T c21 = mix(c11, c12, amount);

	return mix(c20, c21, amount); // c30
}

template<typename T, typename TB>
constexpr T mix_polynomial(const TB time[], const T data[], int samples, TB amount, T init)
{
	T result = init;
	for(int i = 0; i < samples; i++)
	{
		T term = data[i];
		for(int j = 0; j < samples; j++)
			if(j != i)
				term = term * (amount - time[j]) / TB(time[i] - time[j]);
		result += term;
	}
	return result;
}

inline float random_float()
{
	return rand() / (float)(RAND_MAX);
}

inline float random_float(float min, float max)
{
	return min + random_float() * (max - min);
}

inline float random_float(float max)
{
	return random_float(0.0f, max);
}

inline float random_angle()
{
	return 2.0f * pi * (rand() / std::nextafter((float)RAND_MAX, std::numeric_limits<float>::max()));
}

constexpr int fxpscale = 1 << 10;

// float to fixed
constexpr int f2fx(float v)
{
	return round_to_int(v * fxpscale);
}
constexpr float fx2f(int v)
{
	return v / (float)fxpscale;
}

// int to fixed
constexpr int i2fx(int v)
{
	return v * fxpscale;
}
constexpr int fx2i(int v)
{
	return v / fxpscale;
}

class fxp
{
	int value;

public:
	constexpr void set(int v)
	{
		value = v;
	}
	constexpr int get() const
	{
		return value;
	}
	constexpr fxp &operator=(int v)
	{
		value = i2fx(v);
		return *this;
	}
	constexpr fxp &operator=(float v)
	{
		value = f2fx(v);
		return *this;
	}
	constexpr operator int() const
	{
		return fx2i(value);
	}
	constexpr operator float() const
	{
		return fx2f(value);
	}
};

template<Numeric T>
constexpr T minimum(T a, T b)
{
	return std::min(a, b);
}
template<Numeric T>
constexpr T minimum(T a, T b, T c)
{
	return std::min(std::min(a, b), c);
}
template<Numeric T>
constexpr T maximum(T a, T b)
{
	return std::max(a, b);
}
template<Numeric T>
constexpr T maximum(T a, T b, T c)
{
	return std::max(std::max(a, b), c);
}
template<typename T>
constexpr T absolute(T a)
{
	return a < T(0) ? -a : a;
}

template<Numeric T>
constexpr bool in_range(T a, T lower, T upper)
{
	return lower <= a && a <= upper;
}
template<Numeric T>
constexpr bool in_range(T a, T upper)
{
	return in_range(a, 0, upper);
}

#endif // BASE_MATH_H