PImage img;

void setup() {
  size(200,200, P3D);
  img = loadImage("house.jpg");
}

float rotation = 0.0;

void draw (){
  background(0);
  image(rotateImage(img, rotation), 0, 0);
  rotation += 0.02;
}

PImage rotateImage (PImage _img, float _rad)
{
  int xm = _img.width;
  int ym = _img.height;
  
  if (_rad == 0) return _img;
  
  PGraphics _bimg = new PGraphics(xm, ym, this);
  _bimg.background(255);
  _bimg.noStroke();
  
  _bimg.translate(xm/2.0, ym/2.0);

  _bimg.rotateZ(_rad);					// <------------

  _bimg.beginShape(QUADS);
   _bimg.texture(img); 
   _bimg.vertex( -(xm/2),  -(ym/2),0,  0,0); 
   _bimg.vertex(  (xm/2),  -(ym/2),0,  xm,0); 
   _bimg.vertex(  (xm/2),   (ym/2),0,  xm,ym); 
   _bimg.vertex( -(xm/2),   (ym/2),0,  0,ym);
  _bimg.endShape();
  
  return (PImage) _bimg;
}