smooth painting

A classical problem with pen and mouse painting in several apps. When you paint with any brush, I get a disappointing angled stroke, and the faster goes the pencil, the worst. I wonder if this is a parameter issue, or maybe a processor, software problem?

thanks

Thanks Haik, but the idea is to take advantage of the paint tool options, in this case applying a write-on effect. That's why I need a smooth and perfect curves, no matter the fast I draw.

thanks
Luis