I'm trying to learn how to use the trear physics plug in. Just to get myself going I droped the source code from one of the examples in the editor and tried to run the code.

import traer.physics.*;

ParticleSystem physics;

Particle p;
Particle anchor;
Spring s;

void setup()
{
 size( 400, 400 );
 smooth();
 fill( 0 );
 framerate( 24 );
 ellipseMode( CENTER );
       
 physics = new ParticleSystem( 5.0, 0.05 );
       
 p = physics.makeParticle( 1.0, width/2, height/2, 0 );
 anchor = physics.makeParticle( 1.0, width/2, height/2, 0 );
 anchor.makeFixed();
 s = physics.makeSpring( p, anchor, 1.0, 0.1, 100 );
}

void draw()
{
 if ( !mousePressed )
   physics.advanceTime( 1.0 );
 else
 {
   p.moveTo( mouseX, mouseY, 0 );
   p.setVelocity( (mouseX - pmouseX), (mouseY - pmouseY), 0 );  // this is so you can throw it...
 }
   
 background( 255 );
 
 line( p.position().x(), p.position().y(), anchor.position().x(), anchor.position().y() );
 ellipse( anchor.position().x(), anchor.position().y(), 5, 5 );
 ellipse( p.position().x(), p.position().y(), 20, 20 );
}


This is supposed to set up two particles and a spring. However I get the following message.

Semantic Error: No accessible method with signature "position()" was found in type "Particle".

which is supposidly in resonce to this line

 p = physics.makeParticle( 1.0, width/2, height/2, 0 );

however I can't figure out what is wrong. I was wondering if some one with more experiance may be abel to explain this.