1 files changed, 74 insertions, 0 deletions
diff --git a/src/math/quat.h b/src/math/quat.h
new file mode 100644
index 0000000..763253b
--- /dev/null
+++ b/src/math/quat.h
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+#ifndef MATH_QUAT_H
+#define MATH_QUAT_H
+
+#include <cmath>
+
+namespace engine::math {
+
+struct Quaternion {
+    static constexpr Quaternion zero() {
+        return {0.f, 0.f, 0.f, 0.f};
+    }
+
+    static constexpr Quaternion one() {
+        return {1.f, 0.f, 0.f, 0.f};
+    }
+
+    static constexpr Quaternion euler_zyx(float a, float b, float c) {
+        float ca = std::cos(a / 2.f), sa = std::sin(a / 2.f),
+              cb = std::cos(b / 2.f), sb = std::sin(b / 2.f),
+              cc = std::cos(c / 2.f), sc = std::sin(c / 2.f);
+        return {
+            ca * cb * cc - sa * sb * sc,
+            sa * cb * cc + ca * sb * sc,
+            ca * sb * cc - sa * cb * sc,
+            ca * cb * sc + sa * sb * cc,
+        };
+    }
+
+    float w, x, y, z;
+
+    constexpr Quaternion() {}
+    constexpr Quaternion(float w, float x, float y, float z) : w{w}, x{x}, y{y}, z{z} {}
+
+    constexpr bool operator==(const Quaternion& other) const & {
+        return w == other.w && x == other.x && y == other.y && z == other.z;
+    }
+
+    constexpr bool operator!=(const Quaternion& other) const & {
+        return !(*this == other);
+    }
+
+    constexpr Quaternion operator+() const & {
+        return *this;
+    }
+
+    constexpr Quaternion operator-() const & {
+        return { -w, -x, -y, -z };
+    }
+
+    constexpr Quaternion operator+(const Quaternion& other) const & {
+        return { w + other.w, x + other.x, y + other.y, z + other.z };
+    }
+
+    constexpr Quaternion operator-(const Quaternion& other) const & {
+        return *this + (-other);
+    }
+
+    constexpr Quaternion operator*(const Quaternion& other) const & {
+        return {
+            w * other.w - x * other.x - y * other.y - z * other.z,
+            w * other.x + x * other.w + y * other.z - z * other.y,
+            w * other.y + y * other.w + z * other.x - x * other.z,
+            w * other.z + z * other.w + x * other.y - y * other.x,
+        };
+    }
+
+    constexpr Quaternion conjugate() const & {
+        return {w, -x, -y, -z};
+    }
+};
+
+}
+
+#endif // MATH_QUAT_H