PDF export won't save with background for my 3d sketch

Processing Coding Questions
1

I have read the Processing docs on PDF export for 3d sketches. For some reason, my sketch won’t save as a PDF with the specified background. It only saves on a white background.

//Stuff for saving stage
import processing.pdf.*;

// global variables
int DIM = 500; // height, width
int N = 20; // n squares down and up
int R = int(DIM/N); // radius of squares

// setup drawing 
void setup(){
  size(500, 500, P3D);
  rectMode(CENTER);
  noFill();
  noLoop();
  stroke(100, 100, 0);
}
 // draw 
void draw() {
  beginRaw(PDF, "output.pdf");
  background(33); // <<<< SHOULD MAKE BACKGROUND GRAY BUT DOES NOT 
  for (int x=R; x<= width-R; x+=R) { // objects across
    for (int y=R; y<=height-R; y+=R) { // objects down
      float z = noise(x,y) * 30; 
      pushMatrix(); // push matrix stack
      translate(x, y, z); // pop out of canvas based on z value
      rect(0, 0, R, R, 2); // draw rectangle 
      popMatrix(); // pop matrix stack 
    } // end x loop
  } // end y loop 
  endRaw();
}
2

this version, as mentioned in the lib reference
https://processing.org/reference/libraries/pdf/index.html
works, but not show anything, just make the pdf file.
also, i change from 3D to 2D ( in setup size AND how noise works )

// PDF background problem
// https://discourse.processing.org/t/pdf-export-wont-save-with-background-for-my-3d-sketch/10460

//Stuff for saving stage
import processing.pdf.*;

// global variables
int DIM = 500; // height, width
int N = 20; // n squares down and up
int R = int(DIM/(N+1)); // radius of squares
PGraphics pdf;

// setup drawing 
void setup() {
  size(500, 500); //, P3D
  rectMode(CENTER);
  noFill();
  stroke(100, 100, 0);
  pdf = createGraphics(500, 500, PDF, "outputG.pdf");

  pdf.beginDraw();
  pdf.background(0,0,80); // <<<< SHOULD MAKE BACKGROUND GRAY BUT DOES NOT 
  pdf.noFill();
  pdf.stroke(100, 100, 0);
  for (int x=R; x<= width-R; x+=R) { // objects across
    for (int y=R; y<=height-R; y+=R) { // objects down
      float z = (noise(x, y) * 2 -1)*3; // 30
      //pushMatrix(); // push matrix stack
      //translate(0, 0, z); // pop out of canvas based on z value
      pdf.rect(x+z, y+z, R, R, 2); // draw rectangle 
      //popMatrix(); // pop matrix stack
    } // end x loop
  } // end y loop 
  //  endRaw();
  pdf.dispose();
  pdf.endDraw();
  exit();
}