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Diffstat (limited to 'external/include/glm/gtx/fast_exponential.inl')
| -rw-r--r-- | external/include/glm/gtx/fast_exponential.inl | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/external/include/glm/gtx/fast_exponential.inl b/external/include/glm/gtx/fast_exponential.inl new file mode 100644 index 0000000..72f9f8f --- /dev/null +++ b/external/include/glm/gtx/fast_exponential.inl @@ -0,0 +1,137 @@ +/// @ref gtx_fast_exponential +/// @file glm/gtx/fast_exponential.inl + +namespace glm +{ + // fastPow: + template <typename genType> + GLM_FUNC_QUALIFIER genType fastPow(genType x, genType y) + { + return exp(y * log(x)); + } + + template <typename T, precision P, template <typename, precision> class vecType> + GLM_FUNC_QUALIFIER vecType<T, P> fastPow(vecType<T, P> const & x, vecType<T, P> const & y) + { + return exp(y * log(x)); + } + + template <typename T> + GLM_FUNC_QUALIFIER T fastPow(T x, int y) + { + T f = static_cast<T>(1); + for(int i = 0; i < y; ++i) + f *= x; + return f; + } + + template <typename T, precision P, template <typename, precision> class vecType> + GLM_FUNC_QUALIFIER vecType<T, P> fastPow(vecType<T, P> const & x, vecType<int, P> const & y) + { + vecType<T, P> Result(uninitialize); + for(length_t i = 0, n = x.length(); i < n; ++i) + Result[i] = fastPow(x[i], y[i]); + return Result; + } + + // fastExp + // Note: This function provides accurate results only for value between -1 and 1, else avoid it. + template <typename T> + GLM_FUNC_QUALIFIER T fastExp(T x) + { + // This has a better looking and same performance in release mode than the following code. However, in debug mode it's slower. + // return 1.0f + x * (1.0f + x * 0.5f * (1.0f + x * 0.3333333333f * (1.0f + x * 0.25 * (1.0f + x * 0.2f)))); + T x2 = x * x; + T x3 = x2 * x; + T x4 = x3 * x; + T x5 = x4 * x; + return T(1) + x + (x2 * T(0.5)) + (x3 * T(0.1666666667)) + (x4 * T(0.041666667)) + (x5 * T(0.008333333333)); + } + /* // Try to handle all values of float... but often shower than std::exp, glm::floor and the loop kill the performance + GLM_FUNC_QUALIFIER float fastExp(float x) + { + const float e = 2.718281828f; + const float IntegerPart = floor(x); + const float FloatPart = x - IntegerPart; + float z = 1.f; + + for(int i = 0; i < int(IntegerPart); ++i) + z *= e; + + const float x2 = FloatPart * FloatPart; + const float x3 = x2 * FloatPart; + const float x4 = x3 * FloatPart; + const float x5 = x4 * FloatPart; + return z * (1.0f + FloatPart + (x2 * 0.5f) + (x3 * 0.1666666667f) + (x4 * 0.041666667f) + (x5 * 0.008333333333f)); + } + + // Increase accuracy on number bigger that 1 and smaller than -1 but it's not enough for high and negative numbers + GLM_FUNC_QUALIFIER float fastExp(float x) + { + // This has a better looking and same performance in release mode than the following code. However, in debug mode it's slower. + // return 1.0f + x * (1.0f + x * 0.5f * (1.0f + x * 0.3333333333f * (1.0f + x * 0.25 * (1.0f + x * 0.2f)))); + float x2 = x * x; + float x3 = x2 * x; + float x4 = x3 * x; + float x5 = x4 * x; + float x6 = x5 * x; + float x7 = x6 * x; + float x8 = x7 * x; + return 1.0f + x + (x2 * 0.5f) + (x3 * 0.1666666667f) + (x4 * 0.041666667f) + (x5 * 0.008333333333f)+ (x6 * 0.00138888888888f) + (x7 * 0.000198412698f) + (x8 * 0.0000248015873f);; + } + */ + + template <typename T, precision P, template <typename, precision> class vecType> + GLM_FUNC_QUALIFIER vecType<T, P> fastExp(vecType<T, P> const & x) + { + return detail::functor1<T, T, P, vecType>::call(fastExp, x); + } + + // fastLog + template <typename genType> + GLM_FUNC_QUALIFIER genType fastLog(genType x) + { + return std::log(x); + } + + /* Slower than the VC7.1 function... + GLM_FUNC_QUALIFIER float fastLog(float x) + { + float y1 = (x - 1.0f) / (x + 1.0f); + float y2 = y1 * y1; + return 2.0f * y1 * (1.0f + y2 * (0.3333333333f + y2 * (0.2f + y2 * 0.1428571429f))); + } + */ + + template <typename T, precision P, template <typename, precision> class vecType> + GLM_FUNC_QUALIFIER vecType<T, P> fastLog(vecType<T, P> const & x) + { + return detail::functor1<T, T, P, vecType>::call(fastLog, x); + } + + //fastExp2, ln2 = 0.69314718055994530941723212145818f + template <typename genType> + GLM_FUNC_QUALIFIER genType fastExp2(genType x) + { + return fastExp(0.69314718055994530941723212145818f * x); + } + + template <typename T, precision P, template <typename, precision> class vecType> + GLM_FUNC_QUALIFIER vecType<T, P> fastExp2(vecType<T, P> const & x) + { + return detail::functor1<T, T, P, vecType>::call(fastExp2, x); + } + + // fastLog2, ln2 = 0.69314718055994530941723212145818f + template <typename genType> + GLM_FUNC_QUALIFIER genType fastLog2(genType x) + { + return fastLog(x) / 0.69314718055994530941723212145818f; + } + + template <typename T, precision P, template <typename, precision> class vecType> + GLM_FUNC_QUALIFIER vecType<T, P> fastLog2(vecType<T, P> const & x) + { + return detail::functor1<T, T, P, vecType>::call(fastLog2, x); + } +}//namespace glm |