1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef _LIBCPP___CMATH_LERP_H
10#define _LIBCPP___CMATH_LERP_H
11
12#include <__config>
13#include <__type_traits/is_arithmetic.h>
14#include <__type_traits/is_same.h>
15#include <__type_traits/promote.h>
16
17#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
18# pragma GCC system_header
19#endif
20
21#if _LIBCPP_STD_VER >= 20
22
23_LIBCPP_BEGIN_NAMESPACE_STD
24
25template <typename _Fp>
26_LIBCPP_HIDE_FROM_ABI constexpr _Fp __lerp(_Fp __a, _Fp __b, _Fp __t) noexcept {
27 if ((__a <= 0 && __b >= 0) || (__a >= 0 && __b <= 0))
28 return __t * __b + (1 - __t) * __a;
29
30 if (__t == 1)
31 return __b;
32 const _Fp __x = __a + __t * (__b - __a);
33 if ((__t > 1) == (__b > __a))
34 return __b < __x ? __x : __b;
35 else
36 return __x < __b ? __x : __b;
37}
38
39_LIBCPP_HIDE_FROM_ABI inline constexpr float lerp(float __a, float __b, float __t) noexcept {
40 return __lerp(__a, __b, __t);
41}
42
43_LIBCPP_HIDE_FROM_ABI inline constexpr double lerp(double __a, double __b, double __t) noexcept {
44 return __lerp(__a, __b, __t);
45}
46
47_LIBCPP_HIDE_FROM_ABI inline constexpr long double lerp(long double __a, long double __b, long double __t) noexcept {
48 return __lerp(__a, __b, __t);
49}
50
51template <class _A1, class _A2, class _A3>
52 requires(is_arithmetic_v<_A1> && is_arithmetic_v<_A2> && is_arithmetic_v<_A3>)
53_LIBCPP_HIDE_FROM_ABI inline constexpr __promote_t<_A1, _A2, _A3> lerp(_A1 __a, _A2 __b, _A3 __t) noexcept {
54 using __result_type = __promote_t<_A1, _A2, _A3>;
55 static_assert(!(
56 _IsSame<_A1, __result_type>::value && _IsSame<_A2, __result_type>::value && _IsSame<_A3, __result_type>::value));
57 return std::__lerp((__result_type)__a, (__result_type)__b, (__result_type)__t);
58}
59
60_LIBCPP_END_NAMESPACE_STD
61
62#endif // _LIBCPP_STD_VER >= 20
63
64#endif // _LIBCPP___CMATH_LERP_H
65