1.5.1 is the previous, stable version of Processing, which still uses Java2D behind the scene, while in the 2.0b series, it uses OpenGL, so with it, you are back to square one.
"is there another way to do this in OpenGL?"
Probably not. OpenGL is a hardware-accelerated technology, doesn't seem compatible with PDF serialization...
"is there another way to do this in OpenGL?"
Probably not. OpenGL is a hardware-accelerated technology, doesn't seem compatible with PDF serialization...