[SOLVED] Draw static rect filling the screen infront of PeasyCam

The middle of the rect is static at the origin, where the camera is facing, and the rect shall also face the camera.
Lik if it's stuck on a stick infront of it.

ignore the text on the picture, it's the best i found
I want to know the coordinates of the corners so can not use camera.beginHUD() or popMatrix() to achieve this since this doesn't give me any coordinates.
Also screenX/Y and the picker library isn't doing what I wan't to do.
Tried to read up on how to do rotation in 3D but euler angles, rotation matrices,quaternions etc is not something I understand at the moment.
Here is my code, with with just Yaw+Roll it works, but with Pitch any other angle than 0 it doesn't.
Use R, Y, P keys to rotate and Enter to reset

import peasy.*;
PeasyCam camera;
float[] rot;
float disx;
float disy;
float yaw,pitch,roll;
void setup(){
  size(600,400,P3D);
  disx=width*0.6;
  disy=height/10;
  camera = new PeasyCam(this, 100);
  camera.setCenterDragHandler(null);
  strokeWeight(3);
}
float [] rec;

void draw(){
 background(180);
 disx=(float)camera.getDistance()*0.86;
 disy=(float)camera.getDistance()*0.57;
 rec = new float [] {-disx,-disy,0,disx,-disy,0,disx,disy,0,-disx,disy,0};
 //rot = camera.getRotations();
 //yaw=rot[0]; pitch=rot[1]; roll=rot[2];

 if(keyPressed){
 float rotspeed=0.03;
 if(key=='p') { pitch += rotspeed; }
 if(key=='y') {   yaw += rotspeed; }
 if(key=='r') {  roll += rotspeed; }
 if(key==ENTER) {  yaw=pitch=roll=0; }
 }
 camera.setRotations(yaw,pitch,roll);

 float sinyaw,cosyaw, sinpitch,cospitch, sinroll, cosroll;
 sinyaw=sin(-yaw-HALF_PI);
 cosyaw=cos(-yaw-HALF_PI);
 sinpitch=sin(pitch-HALF_PI);
 cospitch=cos(pitch-HALF_PI);
 cosroll=cos(roll);
 sinroll=sin(roll);

 for(int i=0; i<12; i+=3){
 float x,y,z,x0,y0,z0;
 x0=x=rec[i]; y0=y=rec[i+1]; z=z0=rec[i+2];

 x=x0*cosroll-y0*sinroll;
 y=y0*cosroll+x0*sinroll;

 z=x0*cospitch;
 y*=sinpitch;

 z=y*cosyaw;
 y*=sinyaw;

 rec[i]=x; rec[i+1]=y; rec[i+2]=z;

 }

 stroke(#ff0000);
 line(0,0,0,100,0,0);
 stroke(#00ff00);
 line(0,0,0,0,100,0);
 stroke(#0000ff);
 line(0,0,0,0,0,100);

 stroke(0);
 line(rec[0],rec[1],rec[2], rec[3],rec[4],rec[5]);
 line(rec[3],rec[4],rec[5], rec[6],rec[7],rec[8]);
 line(rec[6],rec[7],rec[8], rec[9],rec[10],rec[11]);
 line(rec[9],rec[10],rec[11], rec[0],rec[1],rec[2]);
}

A bit simpler example just a rotating square and static camera, only rotating in one axis at the time.
Also just found this https://khanacademy.org/computer-programming/3d-tutorial-4/1648921303

import peasy.*;
PeasyCam camera;
float S,C,R,D;
float [] rec;
void setup(){
  size(600,400,P3D);
  camera = new PeasyCam(this, 100);
  camera.setCenterDragHandler(null);
  strokeWeight(3);
  D=30;
}
void draw(){
 background(180);
 rec = new float [] {-D,-D,0,D,-D,0,D,D,0,-D,D,0};
 camera.setRotations(0,0,0);
 R+=PI/60;
 S=sin(R);
 C=cos(R);
 for(int i=0; i<12; i+=3){
 float x,y,z,x0,y0,z0;
 x0=x=rec[i]; y0=y=rec[i+1]; z=z0=rec[i+2];
 if(frameCount%180<60){
 x=x0*C-y0*S;
 y=y0*C+x0*S;
 }
 else if(frameCount%180<120){
 z=z0*C-x0*S;
 x=x0*C+z0*S;
 }
 else{
 y=y0*C-z0*S;
 z=z0*C+y0*S;
 }
 rec[i]=x; rec[i+1]=y; rec[i+2]=z;
 }
 stroke(#ff0000);
 line(0,0,0,100,0,0);
 stroke(#00ff00);
 line(0,0,0,0,100,0);
 stroke(#0000ff);
 line(0,0,0,0,0,100);
 stroke(0);
 line(rec[0],rec[1],rec[2], rec[3],rec[4],rec[5]);
 line(rec[3],rec[4],rec[5], rec[6],rec[7],rec[8]);
 line(rec[6],rec[7],rec[8], rec[9],rec[10],rec[11]);
 line(rec[9],rec[10],rec[11], rec[0],rec[1],rec[2]);
}