Source

love / src / common / math.h

/**
 * Copyright (c) 2006-2013 LOVE Development Team
 *
 * This software is provided 'as-is', without any express or implied
 * warranty.  In no event will the authors be held liable for any damages
 * arising from the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 *    claim that you wrote the original software. If you use this software
 *    in a product, an acknowledgment in the product documentation would be
 *    appreciated but is not required.
 * 2. Altered source versions must be plainly marked as such, and must not be
 *    misrepresented as being the original software.
 * 3. This notice may not be removed or altered from any source distribution.
 **/

#ifndef LOVE_MATH_H
#define LOVE_MATH_H

#include <climits> // for CHAR_BIT
#include <cstdlib> // for rand() and RAND_MAX

/* Definitions of useful mathematical constants
 * M_E        - e
 * M_LOG2E    - log2(e)
 * M_LOG10E   - log10(e)
 * M_LN2      - ln(2)
 * M_LN10     - ln(10)
 * M_PI       - pi
 * M_PI_2     - pi/2
 * M_PI_4     - pi/4
 * M_1_PI     - 1/pi
 * M_2_PI     - 2/pi
 * M_2_SQRTPI - 2/sqrt(pi)
 * M_SQRT2    - sqrt(2)
 * M_SQRT1_2  - 1/sqrt(2)
 */

#define LOVE_M_E        2.71828182845904523536
#define LOVE_M_LOG2E    1.44269504088896340736
#define LOVE_M_LOG10E   0.434294481903251827651
#define LOVE_M_LN2      0.693147180559945309417
#define LOVE_M_LN10     2.30258509299404568402
#define LOVE_M_PI       3.14159265358979323846
#define LOVE_M_PI_2     1.57079632679489661923
#define LOVE_M_PI_4     0.785398163397448309616
#define LOVE_M_1_PI     0.318309886183790671538
#define LOVE_M_2_PI     0.636619772367581343076
#define LOVE_M_2_SQRTPI 1.12837916709551257390
#define LOVE_M_SQRT2    1.41421356237309504880
#define LOVE_M_SQRT1_2  0.707106781186547524401
#define LOVE_M_TORAD	(float)(LOVE_M_PI/180.0)
#define LOVE_M_TODEG    (float)(180.0/LOVE_M_PI)
#define LOVE_TORAD(x)	(float)(x*LOVE_M_TORAD)
#define LOVE_TODEG(x)	(float)(x*LOVE_M_TODEG)

namespace love
{

struct vertex
{
	unsigned char r, g, b, a;
	float x, y;
	float s, t;
};

inline int next_p2(int x)
{
	x += (x == 0);
	x--;
	for (unsigned int i = 1; i < sizeof(int)*CHAR_BIT; i <<= 1) x |= x >> i;
	return ++x;
}

inline float next_p2(float x)
{
	return static_cast<float>(next_p2(static_cast<int>(x)));
}

/**
 * Draws a random number from a uniform distribution.
 * @returns Uniformly distributed random number in [0:1).
 */
inline float random()
{
	// to satisfy picky compilers...
	return float(double(rand() % RAND_MAX) / double(RAND_MAX));
}

/**
 * Draws a random number from a uniform distribution.
 * @return Uniformly distributed random number in [0:max).
 */
inline float random(float max)
{
	return random() * max;
}

/**
 * Draws a random number from a uniform distribution.
 * @return Uniformly distributed random number in [min:max).
 */
inline float random(float min, float max)
{
	return random(max - min) + min;
}

/**
 * Draws a random number from a normal/gaussian distribution.
 * @param o Standard deviation of the distribution.
 * @returns Normal distributed random number with mean 0 and variance o^2.
 */
float random_normal(float o = 1.);
#define random_gaussian random_normal

} // love

#endif // LOVE_MATH_H