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73 lines
2.0 KiB
73 lines
2.0 KiB
/** |
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* @file math.h |
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* |
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* Math utility functions |
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*/ |
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#pragma once |
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namespace devilution { |
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namespace math { |
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/** |
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* @brief Compute sign of t |
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* @tparam T Any arithmetic type |
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* @param t Value to compute sign of |
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* @return -1 if t < 0, 1 if t > 0, 0 if t == 0 |
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*/ |
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template <typename T> |
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int Sign(T t) |
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{ |
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return (t > T(0)) - (t < T(0)); |
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} |
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/** |
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* @brief Linearly interpolate from a towards b using mixing value t |
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* @tparam V Any arithmetic type, used for interpolants and return value |
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* @tparam T Any arithmetic type, used for interpolator |
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* @param a Low interpolation value (returned when t == 0) |
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* @param b High interpolation value (returned when t == 1) |
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* @param t Interpolator, commonly in range [0..1], values outside this range will extrapolate |
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* @return a + (b - a) * t |
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*/ |
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template <typename V, typename T> |
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V Lerp(V a, V b, T t) |
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{ |
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return a + (b - a) * t; |
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} |
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/** |
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* @brief Inverse lerp, given two key values a and b, and a free value v, determine mixing factor t so that v = Lerp(a, b, t) |
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* @tparam T Any arithmetic type |
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* @param a Low key value (function returns 0 if v == a) |
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* @param b High key value (function returns 1 if v == b) |
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* @param v Mixing factor, commonly in range [a..b] to get a return [0..1] |
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* @return Value t so that v = Lerp(a, b, t); or 0 if b == a |
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*/ |
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template <typename T> |
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T InvLerp(T a, T b, T v) |
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{ |
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if (b == a) |
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return T(0); |
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return (v - a) / (b - a); |
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} |
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/** |
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* @brief Remaps value v from range [inMin, inMax] to [outMin, outMax] |
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* @tparam T Any arithmetic type |
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* @param inMin First bound of input range |
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* @param inMax Second bound of input range |
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* @param outMin First bound of output range |
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* @param outMax Second bound of output range |
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* @param v Value to remap |
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* @return Transformed value so that InvLerp(inMin, inMax, v) == InvLerp(outMin, outMax, return) |
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*/ |
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template <typename T> |
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T Remap(T inMin, T inMax, T outMin, T outMax, T v) |
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{ |
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auto t = InvLerp(inMin, inMax, v); |
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return Lerp(outMin, outMax, t); |
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} |
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} // namespace math |
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} // namespace devilution
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