+ const GL::Vector3 &up = base_camera.get_up_direction();
+ GL::Vector3 right = normalize(cross(base_camera.get_look_direction(), up));
+ GL::Vector4 columns[4];
+ columns[0] = compose(right, 0.0f);
+ columns[1] = compose(up, 0.0f);
+ columns[2] = compose(cross(right, up), 0.0f);
+ columns[3] = compose(base_camera.get_position()+base_camera.get_up_direction()*elevation_offset, 1.0f);
+ base_matrix = GL::Matrix::from_columns(columns);