interpolator.hpp

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#pragma once
#include <glm/common.hpp>
#include <le2d/transform.hpp>
#include <cmath>
 
namespace le::anim {
template <typename Type>
struct Interpolator;
 
template <typename Type>
constexpr auto interpolate(Type const& a, Type const& b, float const t) {
    return Interpolator<Type>{}(a, b, t);
}
 
template <typename Type>
struct Interpolator {
    constexpr auto operator()(Type const& a, Type const& b, float const t) const { return std::lerp(a, b, t); }
};
 
template <typename Type, glm::length_t Length>
struct Interpolator<glm::vec<Length, Type>> {
    constexpr auto operator()(glm::vec<Length, Type> const a, glm::vec<Length, Type> const b, float const t) const { return glm::mix(a, b, t); }
};
 
template <>
struct Interpolator<Transform> {
    auto operator()(Transform const& a, Transform const& b, float const t) const {
        return Transform{
            .position = interpolate(a.position, b.position, t),
            .orientation = nvec2::from_radians(interpolate(a.orientation.to_radians(), b.orientation.to_radians(), t)),
            .scale = interpolate(a.scale, b.scale, t),
        };
    }
};
} // namespace le::anim