9.5.2

770 • CHAPTER 17
OBJECT MANAGER • 771
No Phong tag (left), Phong tag applied (right).
The following cylinders demonstrate the effect of the smoothing angle. The cylinder on the left has
smoothing with no angle limit specied (i.e. all angles are smoothed), the middle cylinder has an angle
limit of 89.5° and the cylinder to the right has no smoothing at all.
No angle limit (left), 89.5 angle limit (center), no smoothing (right).
When CINEMA 4D calculates the Phong shading, it assumes that the surface normals are aligned. If
this is not the case, shading anomalies may appear. All primitive objects are aligned by default.
Smoothing is a good way to reduce render time and save on memory. Without the Phong tag, an object
would require a far greater number of polygons in order to appear smooth. Note that smoothing can
only take place across connected surfaces (surfaces that share points).
How Phong shading works
Each surface has a normal (often called a ‘surface normal’) that is perpendicular to its surface. The
color and brightness of a point is determined by the angles which the normal forms with the rays of the
camera and the light sources. Without smoothing, two connected surfaces will have a hard transition,
because each surface has its own normal. This will cause brightness bands.