Use this setting to define the angle to which two neighboring surfaces should be rounded. To do so, activate the Angle Limit option and enter the desired angle here.
The effect of this function is shown in the example below. A simple cylinder was used as a test object. The image at the top Phong Angle was applied without Angle Limit, in the center Angle Limit was set to 89.5° and the cylinder at the bottom has no Phong Angle applied.
When calculating smoothed objects, Cinema 4D always assumes the polygons (and their Normals vectors) are oriented uniformly. If they are not, shadow anomalies can occur when the image is rendered. All primitives, though, have a uniform orientation.
When in edge mode, Cinema 4D allows you to break the Phong shading along edges using the Break Phong Shading command (Mesh menu).
When breaking individual edges, the effect will only occur if the end points of the edge are surrounded by connected polygons (Break Phong Shading -
You can enable or disable the effect via the Use Edge Breaks option.
The following types of Generators object make use of these new Phong features: Extrude, Lathe and Sweep. To see the difference, select the Generator object’s Phong tag and in the Attribute Manager, disable the Use Edge Breaks option. Provided the option is enabled, the edges will be sharp.