Return internal class.

Opacity of the brush in interval 0..1 0 -- full transparency 1 -- full opacity. The default value is 1.

Shading model that should be applied to an object if it's painted with this brush. You should understand that different shading models are not always supported. For example if you paint some background with the brush only plain shading (read -- no shading) is possible. But if you paint some 3d-object different models can be chosen (it is possible to draw this object as if it was lightened by some light source).