Push/Pop Limit Workaround (Java Mode)

MatrixFrameGL.java

/**
 * Push/Pop Limit Workaround (v1.0.1)
 * GoToLoop (2020/Aug/22)
 *
 * Discourse.Processing.org/t/too-many-calls-to-pushmatrix/23411/8
 * Gist.GitHub.com/GoToLoop/e35ac69e9bd4dbbcce557218c3b20588
 */

// Comment out the package statement below if it's inside a ".java" file:
package processing.core;

import processing.opengl.PGraphicsOpenGL;

//static // Comment the keyword static if it's inside a ".java" file!
public class MatrixFrameGL implements Cloneable
{
  public PMatrix modelview, modelviewInv, camera, cameraInv;

  public MatrixFrameGL() {
  }

  public MatrixFrameGL(final PGraphics pg) {
    pushMatrix(pg);
  }

  public MatrixFrameGL pushMatrix(final PGraphics pg) {
    return pushMatrix((PGraphicsOpenGL) pg);
  }

  public MatrixFrameGL pushMatrix(final PGraphicsOpenGL pg) {
    modelview    = pg.modelview.get();
    modelviewInv = pg.modelviewInv.get();
    camera       = pg.camera.get();
    cameraInv    = pg.cameraInv.get();
    return this;
  }

  public MatrixFrameGL popMatrix(final PGraphics pg) {
    return popMatrix((PGraphicsOpenGL) pg);
  }

  public MatrixFrameGL popMatrix(final PGraphicsOpenGL pg) {
    pg.modelview.set(modelview);
    pg.modelviewInv.set(modelviewInv);
    pg.camera.set(camera);
    pg.cameraInv.set(cameraInv);
    return this;
  }

  @Override public MatrixFrameGL clone() {
    try {
      final MatrixFrameGL frame = (MatrixFrameGL) super.clone();
      frame.modelview           = modelview.get();
      frame.modelviewInv        = modelviewInv.get();
      frame.camera              = camera.get();
      frame.cameraInv           = cameraInv.get();
      return frame;
    }
    catch (final CloneNotSupportedException e) {
      throw new RuntimeException(e);
    }
  }
}

Push_Pop_Limit_Workaround.pde

/**
 * Push/Pop Limit Workaround (v1.0.1)
 * GoToLoop (2020/Aug/22)
 *
 * Discourse.Processing.org/t/too-many-calls-to-pushmatrix/23411/8
 * Gist.GitHub.com/GoToLoop/e35ac69e9bd4dbbcce557218c3b20588
 */

import java.util.Queue;
import java.util.ArrayDeque;

final Queue<MatrixFrameGL> frames = new ArrayDeque<MatrixFrameGL>();

static final int BOXES = 32, SIZE = 6, MOV = SIZE << 2;
static final float ROT = TAU / BOXES;

void setup() {
  size(1200, 200, P3D);
  noLoop();
  stroke(#FFFF00); // yellow
}

void draw() {
  clear();

  translate(0, height >> 2);
  fill(#FF0000); // red
  recursiveBoxes(BOXES, SIZE, MOV, ROT, g, null); // 32 boxes

  translate(0, height >> 1);
  fill(#0000FF); // blue
  recursiveBoxes(BOXES * 3 >> 1, SIZE, MOV, ROT, g, frames); // 48 boxes
}

static final void recursiveBoxes(
  final int qty, final int size, final int moveX, final float rot, 
  final PGraphics pg, 
  final Queue<MatrixFrameGL> frames // pass null to use regular push/pop
  )
{
  if (qty <= 0)  return;

  if (frames != null)  frames.add(new MatrixFrameGL(pg));
  else                 pg.pushMatrix();

  pg.translate(moveX, 0);
  pg.rotateX(rot);
  pg.box(size);

  recursiveBoxes(qty - 1, size, moveX, rot, pg, frames);

  if (frames != null)  frames.remove().popMatrix(pg);
  else                 pg.popMatrix();
}