PImage a;

void setup(){

 a=loadImage("testimg.jpg")

 size(1000,1000,P3D);

}

int distance=0;

void draw(){

 background(0);

 image(a,50,50);

 camera(80,80,80,80,distance++,80,0,1,0);

}

Nothing happens.

My first guess is that you need to pre-load the 'testimg.jpg'.

From the Processing.js loadImage() docs: 

@pjs preload must be used to preload the image

More info here:
http://processingjs.org/reference/loadImage_/

You may want to read this very carefully (especially clause 7):

http://processingjs.org/articles/p5QuickStart.html

So i found out that using a PImage this way and using image(img,x,y) doesn't give you a real 3D image. Please correct me if i'm off tangent. The only way is to create a vertex and texture it onto the surface. This would make it the traditional way of doing 3D objects, like in the really old days, without the whole projection mapping that the current crop of 3D programs can do, so it's not a really good thing.

I was trying to have objects moving on that plane, and another camera focused on the plane. I found the java version of what i wrote to have the side effect of auto tiling using damjker's OCD library, but no javascript version exists.

So if anyone has an idea of how to embed a moving sketch within a sketch, that would be an interesting development.

But still is there a way in which you can dynamically project one sketch onto a surface, and put a camera on it and move the camera about?