AtomicGameEngine/Source/Atomic/Math/MathDefs.h

//
// Copyright (c) 2008-2016 the Urho3D project.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//

#pragma once

#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable:4244) // Conversion from 'double' to 'float'
#pragma warning(disable:4702) // unreachable code
#endif

#include "../Math/Random.h"

#include <cstdlib>
#include <cmath>
#include <limits>

namespace Atomic
{

#undef M_PI
static const float M_PI = 3.14159265358979323846264338327950288f;
static const float M_HALF_PI = M_PI * 0.5f;
static const int M_MIN_INT = 0x80000000;
static const int M_MAX_INT = 0x7fffffff;
static const unsigned M_MIN_UNSIGNED = 0x00000000;
static const unsigned M_MAX_UNSIGNED = 0xffffffff;

static const float M_EPSILON = 0.000001f;
static const float M_LARGE_EPSILON = 0.00005f;
static const float M_MIN_NEARCLIP = 0.01f;
static const float M_MAX_FOV = 160.0f;
static const float M_LARGE_VALUE = 100000000.0f;
static const float M_INFINITY = (float)HUGE_VAL;
static const float M_DEGTORAD = M_PI / 180.0f;
static const float M_DEGTORAD_2 = M_PI / 360.0f;    // M_DEGTORAD / 2.f
static const float M_RADTODEG = 1.0f / M_DEGTORAD;

/// Intersection test result.
enum Intersection
{
    OUTSIDE,
    INTERSECTS,
    INSIDE
};

/// Check whether two floating point values are equal within accuracy.
template <class T>
inline bool Equals(T lhs, T rhs) { return lhs + std::numeric_limits<T>::epsilon() >= rhs && lhs - std::numeric_limits<T>::epsilon() <= rhs; }

/// Linear interpolation between two values.
template <class T, class U>
inline T Lerp(T lhs, T rhs, U t) { return lhs * (1.0 - t) + rhs * t; }

/// Return the smaller of two values.
template <class T, class U>
inline T Min(T lhs, U rhs) { return lhs < rhs ? lhs : rhs; }

/// Return the larger of two values.
template <class T, class U>
inline T Max(T lhs, U rhs) { return lhs > rhs ? lhs : rhs; }

/// Return absolute value of a value
template <class T>
inline T Abs(T value) { return value >= 0.0 ? value : -value; }

/// Return the sign of a float (-1, 0 or 1.)
template <class T>
inline T Sign(T value) { return value > 0.0 ? 1.0 : (value < 0.0 ? -1.0 : 0.0); }

/// Check whether a floating point value is NaN.
/// Use a workaround for GCC, see https://github.com/urho3d/Urho3D/issues/655
#ifndef __GNUC__
inline bool IsNaN(float value) { return value != value; }
#else

inline bool IsNaN(float value)
{
    unsigned u = *(unsigned*)(&value);
    return (u & 0x7fffffff) > 0x7f800000;
}

#endif

/// Clamp a number to a range.
template <class T>
inline T Clamp(T value, T min, T max)
{
    if (value < min)
        return min;
    else if (value > max)
        return max;
    else
        return value;
}

/// Smoothly damp between values.
template <class T>
inline T SmoothStep(T lhs, T rhs, T t)
{
    t = Clamp((t - lhs) / (rhs - lhs), T(0.0), T(1.0)); // Saturate t
    return t * t * (3.0 - 2.0 * t);
}

/// Return sine of an angle in degrees. Uses sinf() for floats, sin() for
/// everything else
template <class T>
inline T Sin(T angle) { return sin(angle * M_DEGTORAD); }
template <> inline float Sin<float>(float angle) { return sinf(angle * M_DEGTORAD); }

/// Return cosine of an angle in degrees. Uses cosf() for floats, cos() for
/// everything else
template <class T>
inline T Cos(T angle) { return cos(angle * M_DEGTORAD); }
template <> inline float Cos<float>(float angle) { return cosf(angle * M_DEGTORAD); }

/// Return tangent of an angle in degrees. Uses tanf() for floats, tan() for
/// everything else
template <class T>
inline T Tan(T angle) { return tan(angle * M_DEGTORAD); }
template <> inline float Tan<float>(float angle) { return tanf(angle * M_DEGTORAD); }

/// Return arc sine in degrees. Uses asinf() for floats, asin() for everything
/// else
template <class T>
inline T Asin(T x) { return M_RADTODEG * asin(Clamp(x, -1.0, 1.0)); }
template <> inline float Asin<float>(float x) { return M_RADTODEG * asinf(Clamp(x, -1.0f, 1.0f)); }

/// Return arc cosine in degrees. Uses acosf() for floats, acos() for
/// everything else
template <class T>
inline T Acos(T x) { return M_RADTODEG * acos(Clamp(x, -1.0, 1.0)); }
template <> inline float Acos<float>(float x) { return M_RADTODEG * acosf(Clamp(x, -1.0f, 1.0f)); }

/// Return arc tangent in degrees. Uses atanf() for floats, atan() for
/// everything else
template <class T>
inline T Atan(T x) { return M_RADTODEG * atan(x); }
template <> inline float Atan<float>(float x) { return M_RADTODEG * atanf(x); }

/// Return arc tangent of y/x in degrees. Uses atan2f() for floats, atan2()
/// for everything else
template <class T>
inline T Atan2(T y, T x) { return M_RADTODEG * atan2(y, x); }
template <> inline float Atan2<float>(float y, float x) { return M_RADTODEG * atan2f(y, x); }

/// Check whether an unsigned integer is a power of two.
inline bool IsPowerOfTwo(unsigned value)
{
    return !(value & (value - 1));
}

/// Round up to next power of two.
inline unsigned NextPowerOfTwo(unsigned value)
{
    // http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
    --value;
    value |= value >> 1;
    value |= value >> 2;
    value |= value >> 4;
    value |= value >> 8;
    value |= value >> 16;
    return ++value;
}

/// Count the number of set bits in a mask.
inline unsigned CountSetBits(unsigned value)
{
    // Brian Kernighan's method
    unsigned count = 0;
    for (count = 0; value; count++)
        value &= value - 1;
    return count;
}

/// Update a hash with the given 8-bit value using the SDBM algorithm.
inline unsigned SDBMHash(unsigned hash, unsigned char c) { return c + (hash << 6) + (hash << 16) - hash; }

/// Return a random float between 0.0 (inclusive) and 1.0 (exclusive.)
inline float Random() { return Rand() / 32768.0f; }

/// Return a random float between 0.0 and range, inclusive from both ends.
inline float Random(float range) { return Rand() * range / 32767.0f; }

/// Return a random float between min and max, inclusive from both ends.
inline float Random(float min, float max) { return Rand() * (max - min) / 32767.0f + min; }

/// Return a random integer between 0 and range - 1.
inline int Random(int range) { return (int)(Random() * range); }

/// Return a random integer between min and max - 1.
inline int Random(int min, int max) { float range = (float)(max - min); return (int)(Random() * range) + min; }

/// Return a random normal distributed number with the given mean value and variance.
inline float RandomNormal(float meanValue, float variance) { return RandStandardNormal() * sqrtf(variance) + meanValue; }

/// Convert float to half float. From https://gist.github.com/martinkallman/5049614
inline unsigned short FloatToHalf(float value)
{
    unsigned inu = *((unsigned*)&value);
    unsigned t1 = inu & 0x7fffffff;         // Non-sign bits
    unsigned t2 = inu & 0x80000000;         // Sign bit
    unsigned t3 = inu & 0x7f800000;         // Exponent

    t1 >>= 13;                              // Align mantissa on MSB
    t2 >>= 16;                              // Shift sign bit into position

    t1 -= 0x1c000;                          // Adjust bias

    t1 = (t3 < 0x38800000) ? 0 : t1;        // Flush-to-zero
    t1 = (t3 > 0x47000000) ? 0x7bff : t1;   // Clamp-to-max
    t1 = (t3 == 0 ? 0 : t1);                // Denormals-as-zero

    t1 |= t2;                               // Re-insert sign bit

    return (unsigned short)t1;
}

/// Convert half float to float. From https://gist.github.com/martinkallman/5049614
inline float HalfToFloat(unsigned short value)
{
    unsigned t1 = value & 0x7fff;           // Non-sign bits
    unsigned t2 = value & 0x8000;           // Sign bit
    unsigned t3 = value & 0x7c00;           // Exponent

    t1 <<= 13;                              // Align mantissa on MSB
    t2 <<= 16;                              // Shift sign bit into position

    t1 += 0x38000000;                       // Adjust bias

    t1 = (t3 == 0 ? 0 : t1);                // Denormals-as-zero

    t1 |= t2;                               // Re-insert sign bit

    float out;
    *((unsigned*)&out) = t1;
    return out;
}

/// Calculate both sine and cosine, with angle in degrees.
ATOMIC_API void SinCos(float angle, float& sin, float& cos);

}

#ifdef _MSC_VER
#pragma warning(pop)
#endif