I'm a professional programmer with no graphics or artistic experience to speak of. Still, I can't and don't want to avoid graphics design entirely. Dabbling in programs such as Gimp (Linux equivalent to Photoshop) is not really to my taste, particularly in cases when my programmer instincts immediately point out that the image in question ought to be generalized and parameterized.

As such, I'm looking at Processing as a programmable drawing tool, not as a means for artistic expression. To get my feet wet, I tried to draw a button like presented there

http://technomono.com/blog/make-a-button-with-rounded-corners/#more-105

I didn't get very far, but along the way it occurred to me that all the tutorials I've seen so far take a lot of artistic latitude when placing color gradients and highlights. The engineering way, I take it, would be to model the button in 3D and add light sources. So much for the theory.

With my little understanding, I can't decide if that idea is at all sensible and if Processing would be a good tool to approach it. I'd appreciate your suggestions and pointers to relevant examples.

I've already tried curves (curveVortex) and lines + arcs for rounded rectangles myself. Can't decide which one I like better.

For the gradient my first idea was to draw lines, too. I take it, in order not to overshoot the rounded corners I'd have to use a mask or alternatively calculate the exact width for each line. However, when I was thinking of these details, the idea struck of doing it in 3D with a light source causing the gradient. Unfortunately, I don't see how to do this, or if it is a good idea to start with.