diff --git a/Code/Framework/AzCore/AzCore/std/math.h b/Code/Framework/AzCore/AzCore/std/math.h index 03f12e6e08..042dcca657 100644 --- a/Code/Framework/AzCore/AzCore/std/math.h +++ b/Code/Framework/AzCore/AzCore/std/math.h @@ -30,4 +30,49 @@ namespace AZStd using std::sqrt; using std::tan; using std::trunc; + +} // namespace AZStd + +// from c++20 standard +namespace AZStd::Internal +{ + template + constexpr T lerp(T a, T b, T t) noexcept + { + if ((a <= 0 && b >= 0) || (a >= 0 && b <= 0)) + { + return t * b + (1 - t) * a; + } + if (t == 1) + { + return b; + } + const T x = a + t * (b - a); + if ((t > 1) == (b > a)) + { + return b < x ? x : b; + } + else + { + return x < b ? x : b; + } + } +} // namespace AZStd::Internal + +namespace AZStd +{ + constexpr float lerp(float a, float b, float t) noexcept + { + return Internal::lerp(a, b, t); + } + + constexpr double lerp(double a, double b, double t) noexcept + { + return Internal::lerp(a, b, t); + } + + constexpr long double lerp(long double a, long double b, long double t) noexcept + { + return Internal::lerp(a, b, t); + } } // namespace AZStd diff --git a/Code/Framework/AzCore/Tests/AZStd/Math.cpp b/Code/Framework/AzCore/Tests/AZStd/Math.cpp new file mode 100644 index 0000000000..5379c9946b --- /dev/null +++ b/Code/Framework/AzCore/Tests/AZStd/Math.cpp @@ -0,0 +1,46 @@ +/* + * Copyright (c) Contributors to the Open 3D Engine Project. + * For complete copyright and license terms please see the LICENSE at the root of this distribution. + * + * SPDX-License-Identifier: Apache-2.0 OR MIT + * + */ + +#include +#include + +namespace UnitTest +{ + template + class StdMathTest : public ::testing::Test + { + }; + + using MathTestConfigs = ::testing::Types; + TYPED_TEST_CASE(StdMathTest, MathTestConfigs); + + TYPED_TEST(StdMathTest, LerpOperations) + { + using AZStd::lerp; + using ::testing::Eq; + using T = TypeParam; + + constexpr T maxNumber = AZStd::numeric_limits::max(); + constexpr T eps = AZStd::numeric_limits::epsilon(); + constexpr T a{ 42 }; + + // exactness: lerp(a,b,0)==a && lerp(a,b,1)==b + EXPECT_THAT(lerp(eps, maxNumber, T(0)), Eq(eps)); + EXPECT_THAT(lerp(eps, maxNumber, T(1)), Eq(maxNumber)); + + // consistency: lerp(a,a,t)==a + EXPECT_THAT(lerp(a, a, T(0.5)), Eq(a)); + EXPECT_THAT(lerp(eps, eps, T(0.5)), Eq(eps)); + + // a few generic tests taken from MathUtilTests.cpp + EXPECT_EQ(T(2.5), lerp(T(2), T(4), T(0.25))); + EXPECT_EQ(T(6.0), lerp(T(2), T(4), T(2.0))); + EXPECT_EQ(T(3.5), lerp(T(2), T(4), T(0.75))); + EXPECT_EQ(T(0.0), lerp(T(2), T(4), T(-1.0))); + } +} // namespace UnitTest diff --git a/Code/Framework/AzCore/Tests/azcoretests_files.cmake b/Code/Framework/AzCore/Tests/azcoretests_files.cmake index d738711a4f..6ba9944f7d 100644 --- a/Code/Framework/AzCore/Tests/azcoretests_files.cmake +++ b/Code/Framework/AzCore/Tests/azcoretests_files.cmake @@ -195,6 +195,7 @@ set(FILES AZStd/LockFreeQueues.cpp AZStd/LockFreeStacks.cpp AZStd/LockTests.cpp + AZStd/Math.cpp AZStd/Numeric.cpp AZStd/Ordered.cpp AZStd/Optional.cpp