how to update codes written in processing2 for processing3?

I found a very interesting code on openprocessing. However, it won't run on processing3 with the following errors.

getMatrix is not available with this renderer.

camera(), or this particular variation of it, is not available with this renderer.

PeasyCam v0.92

directionalLight() is not available with this renderer.

ambientLight() is not available with this renderer.

sphere() is not available with this renderer.

vertex() with x, y, and z coordinates can only be used with a renderer that supports 3D, such as >P3D or OPENGL. Use a version without a z-coordinate instead.

I try to find libraries with peasyCam, there is one and I downloaded it, but still the same errors. Is it because those functions are not updated for processing3?

what is the easiest solution to these errors?

or should I install processing2 to run this code? but I couldn't find the place to download the older version of processing.

Thanks a lot