Calculate Normals
The calculate normals command serves to automatically calculate normals of an active object . The normal is a vector perpendicular to the object face surface. Is is used to calculate face lighting. The normal represents a direction in which must be located a light source for the face to be maximal lighted.
As a command parameter a maximal angle is entered that normals of different faces may hold in the contact vertex to be applied surface smoothing. The default angle value is equal to 0.5 , i.e. 30 degrees approximately. Surface between faces with lower angle will be smoothed, i.e. ligting between faces will change smoothly. For faces with greater angle an unsmoothed normal will be used, a sharp edge will be observable between faces. By setting an angle to zero all smoothing will be switched off, a sharp edge will be observable between all faces. By setting to pi all face edges will be smoothed.