1 files changed, 38 insertions, 7 deletions

diff --git a/src/common/quaternion.h b/src/common/quaternion.h
index 370198ae0..4d0871eb4 100644
--- a/src/common/quaternion.h
+++ b/src/common/quaternion.h
@@ -14,35 +14,66 @@ public:
     Vec3<T> xyz;
     T w{};
 
-    Quaternion<decltype(-T{})> Inverse() const {
+    [[nodiscard]] Quaternion<decltype(-T{})> Inverse() const {
         return {-xyz, w};
     }
 
-    Quaternion<decltype(T{} + T{})> operator+(const Quaternion& other) const {
+    [[nodiscard]] Quaternion<decltype(T{} + T{})> operator+(const Quaternion& other) const {
         return {xyz + other.xyz, w + other.w};
     }
 
-    Quaternion<decltype(T{} - T{})> operator-(const Quaternion& other) const {
+    [[nodiscard]] Quaternion<decltype(T{} - T{})> operator-(const Quaternion& other) const {
         return {xyz - other.xyz, w - other.w};
     }
 
-    Quaternion<decltype(T{} * T{} - T{} * T{})> operator*(const Quaternion& other) const {
+    [[nodiscard]] Quaternion<decltype(T{} * T{} - T{} * T{})> operator*(
+        const Quaternion& other) const {
         return {xyz * other.w + other.xyz * w + Cross(xyz, other.xyz),
                 w * other.w - Dot(xyz, other.xyz)};
     }
 
-    Quaternion<T> Normalized() const {
+    [[nodiscard]] Quaternion<T> Normalized() const {
         T length = std::sqrt(xyz.Length2() + w * w);
         return {xyz / length, w / length};
     }
+
+    [[nodiscard]] std::array<decltype(-T{}), 16> ToMatrix() const {
+        const T x2 = xyz[0] * xyz[0];
+        const T y2 = xyz[1] * xyz[1];
+        const T z2 = xyz[2] * xyz[2];
+
+        const T xy = xyz[0] * xyz[1];
+        const T wz = w * xyz[2];
+        const T xz = xyz[0] * xyz[2];
+        const T wy = w * xyz[1];
+        const T yz = xyz[1] * xyz[2];
+        const T wx = w * xyz[0];
+
+        return {1.0f - 2.0f * (y2 + z2),
+                2.0f * (xy + wz),
+                2.0f * (xz - wy),
+                0.0f,
+                2.0f * (xy - wz),
+                1.0f - 2.0f * (x2 + z2),
+                2.0f * (yz + wx),
+                0.0f,
+                2.0f * (xz + wy),
+                2.0f * (yz - wx),
+                1.0f - 2.0f * (x2 + y2),
+                0.0f,
+                0.0f,
+                0.0f,
+                0.0f,
+                1.0f};
+    }
 };
 
 template <typename T>
-auto QuaternionRotate(const Quaternion<T>& q, const Vec3<T>& v) {
+[[nodiscard]] auto QuaternionRotate(const Quaternion<T>& q, const Vec3<T>& v) {
     return v + 2 * Cross(q.xyz, Cross(q.xyz, v) + v * q.w);
 }
 
-inline Quaternion<float> MakeQuaternion(const Vec3<float>& axis, float angle) {
+[[nodiscard]] inline Quaternion<float> MakeQuaternion(const Vec3<float>& axis, float angle) {
     return {axis * std::sin(angle / 2), std::cos(angle / 2)};
 }