Manipulating Object Normals

Object normals are vectors that are perpendicular to the surface. They are used in lighting calculations to determine how the light should bounce off a surface at any particular point. By manipulating them, you can control the diffuse and specular light contributions.

To Manipulate Object Normals

1.

Select 3D > Modify > Normals to insert a Normals node anywhere after the 3D object whose lighting you want to adjust.

2.

Connect a Camera, Axis, or light node to the Normals node’s lookat input.

3.

In the Normals controls, open the action dropdown menu and select:

• unchanged to make no changes.

• set to assign the normals value to the normal x, y, and z fields.

• build to rebuild each normal based on the surrounding vertices. Adjust the threshold angle slider to determine the break angle where two faces no longer constitute a smooth surface. An angle of 0 means all faces are flat, whereas 180 means all faces are smooth. A good average setting is 60.

• lookat to point all normals towards the Normals node’s lookat input.

• delete to remove the named attribute from the object. For example, if you remove the N attribute, the object has no normals.