Calling PGraphics.background clears the primary surface on GLES2

[gohai]

The following code works on OS X, but on the Raspberry Pi (GLES2 driver), the background doesn't accumulate over multiple frames. The call that triggers this is background() on an offscreen PGraphics object. It works fine without. @codeanticode Any ideas?

PGraphics pg;

void setup() {
  size(200, 200, P2D);
  pg = createGraphics(200, 200, P2D);
  background(0);
}

void draw() {
  // this shouldn't be required either, separate bug
  if (frameCount == 1) {
    background(0);
  }
  pg.beginDraw();
  pg.background(255, 0, 0);
  pg.endDraw();
  noStroke();
  fill(255);
  rect(frameCount, height/2-5, 10, 10);
}

[codeanticode]

@gohai Thanks for flagging this. I did some improvements in the Android renderer that solved similar issues, I will look into port them over to Java, since my guess is that they would solve the issue on RPi.