Quaternion.from_matrix about gl3n HOT 3 CLOSED

    /// Creates a quaternion from a 3x3 matrix.
    /// Params:
    ///  matrix = 3x3 matrix (rotation)
    /// Returns: A quaternion representing the rotation (3x3 matrix)
    static Quaternion from_matrix(Matrix!(qt, 3, 3) matrix) {
        Quaternion ret;

        auto mat = matrix.matrix;
        qt trace = mat[0][0] + mat[1][1] + mat[2][2];

        if(trace > 0) {
            qt s = 0.5 / sqrt(trace + 1.0f);

            ret.w = to!qt(0.25 / s);
            ret.x = to!qt((mat[2][1] - mat[1][2]) * s);
            ret.y = to!qt((mat[0][2] - mat[2][0]) * s);
            ret.z = to!qt((mat[1][0] - mat[0][1]) * s);
        } else if((mat[0][0] > mat[1][1]) && (mat[0][0] > mat[2][2])) {
            qt s = 2.0 * sqrt(1.0 + mat[0][0] - mat[1][1] - mat[2][2]);

            ret.w = to!qt((mat[2][1] - mat[1][2]) / s);
            ret.x = to!qt(0.25f * s);
            ret.y = to!qt((mat[0][1] + mat[1][0]) / s);
            ret.z = to!qt((mat[0][2] + mat[2][0]) / s);
        } else if(mat[1][1] > mat[2][2]) {
            qt s = 2.0 * sqrt(1 + mat[1][1] - mat[0][0] - mat[2][2]);

            ret.w = to!qt((mat[0][2] - mat[2][0]) / s);
            ret.x = to!qt((mat[0][1] + mat[1][0]) / s);
            ret.y = to!qt(0.25f * s);
            ret.z = to!qt((mat[1][2] + mat[2][1]) / s);
        } else {
            qt s = 2.0 * sqrt(1 + mat[2][2] - mat[0][0] - mat[1][1]);

            ret.w = to!qt((mat[1][0] - mat[0][1]) / s);
            ret.x = to!qt((mat[0][2] + mat[2][0]) / s);
            ret.y = to!qt((mat[1][2] + mat[2][1]) / s);
            ret.z = to!qt(0.25f * s);
        }

        return ret;
    }