diff options
Diffstat (limited to 'src/math/quat.hpp')
| -rw-r--r-- | src/math/quat.hpp | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/src/math/quat.hpp b/src/math/quat.hpp index 51392e7..9687c98 100644 --- a/src/math/quat.hpp +++ b/src/math/quat.hpp @@ -2,6 +2,7 @@ #define MATH_QUAT_HPP #include <cmath> +#include "math/vector.hpp" namespace engine::math { @@ -30,6 +31,23 @@ struct Quaternion { return {std::cos(a / 2.f), 0.f, std::sin(a / 2.f), 0.f}; } + static constexpr Quaternion look_towards(const Vector3& dir, const Vector3& up) { + // TODO: extract common code between Matrix4::look_at and this. We should have something + // similar to a function returning a 3x3 matrix which does: + // e_x -> up.cross(-dir).normalize() + // e_y -> (-dir).cross(e_x).normalize() + // e_z -> (-dir).normalize() + Vector3 new_x = up.cross(-dir).normalize(); + Vector3 new_y = (-dir).cross(new_x).normalize(); + Vector3 new_z = (-dir).normalize(); + return { + std::sqrt(std::max(0.f, new_x.x + new_y.y + new_z.z + 1.f)) / 2.f, + std::copysign(std::sqrt(std::max(0.f, new_x.x - new_y.y - new_z.z + 1.f)) / 2.f, new_y.z - new_z.y), + std::copysign(std::sqrt(std::max(0.f, -new_x.x + new_y.y - new_z.z + 1.f)) / 2.f, new_z.x - new_x.z), + std::copysign(std::sqrt(std::max(0.f, -new_x.x - new_y.y + new_z.z + 1.f)) / 2.f, new_x.y - new_y.x), + }; + } + float w, x, y, z; constexpr Quaternion() {} @@ -71,6 +89,14 @@ struct Quaternion { constexpr Quaternion conjugate() const & { return {w, -x, -y, -z}; } + + constexpr Vector3 rot(const Vector3& v) const & { + return { + (2.f * (w * w + x * x) - 1.f) * v.x + (2.f * (x * y - w * z) ) * v.y + (2.f * (x * z + w * y) ) * v.z, + (2.f * (x * y + w * z) ) * v.x + (2.f * (w * w + y * y) - 1.f) * v.y + (2.f * (y * z - w * x) ) * v.z, + (2.f * (x * z - w * y) ) * v.x + (2.f * (y * z + w * x) ) * v.y + (2.f * (w * w + z * z) - 1.f) * v.z, + }; + } }; } |