// provided by JohnG
// http://processing.org/discourse/yabb_beta/YaBB.cgi?board=OpenGL;action=display;num=1176483247
pt fromOrigin() { 
  ((PGraphicsOpenGL)g).beginGL(); 
  int viewport[] = new int[4]; 
  double[] proj=new double[16]; 
  double[] model=new double[16]; 
  gl.glGetIntegerv(GL.GL_VIEWPORT, viewport, 0); 
  gl.glGetDoublev(GL.GL_PROJECTION_MATRIX,proj,0); 
  gl.glGetDoublev(GL.GL_MODELVIEW_MATRIX,model,0); 
  FloatBuffer fb=ByteBuffer.allocateDirect(4).order(ByteOrder.nativeOrder()).asFloatBuffer(); 
  gl.glReadPixels(mouseX, height-mouseY, 1, 1, GL.GL_DEPTH_COMPONENT, GL.GL_FLOAT, fb); 
  fb.rewind(); 
  double[] mousePosArr=new double[4]; 
  glu.gluUnProject(0,0,-D, model,0,proj,0,viewport,0,mousePosArr,0); 
  ((PGraphicsOpenGL)g).endGL(); 
  return new pt((float)mousePosArr[0],(float)mousePosArr[1],(float)mousePosArr[2]);
  }
  
pt fromMouse() { 
  ((PGraphicsOpenGL)g).beginGL(); 
  int viewport[] = new int[4]; 
  double[] proj=new double[16]; 
  double[] model=new double[16]; 
  gl.glGetIntegerv(GL.GL_VIEWPORT, viewport, 0); 
  gl.glGetDoublev(GL.GL_PROJECTION_MATRIX,proj,0); 
  gl.glGetDoublev(GL.GL_MODELVIEW_MATRIX,model,0); 
  FloatBuffer fb=ByteBuffer.allocateDirect(4).order(ByteOrder.nativeOrder()).asFloatBuffer(); 
  gl.glReadPixels(mouseX, height-mouseY, 1, 1, GL.GL_DEPTH_COMPONENT, GL.GL_FLOAT, fb); 
  fb.rewind(); 
  double[] mousePosArr=new double[4]; 
  glu.gluUnProject((double)mouseX,height-(double)mouseY,(double)fb.get(0), model,0,proj,0,viewport,0,mousePosArr,0); 
  ((PGraphicsOpenGL)g).endGL(); 
  return new pt((float)mousePosArr[0],(float)mousePosArr[1],(float)mousePosArr[2]);
}

  float[] getMouse3D() 
{ 
  ((PGraphicsOpenGL)g).beginGL(); 
  int viewport[] = new int[4]; 
  double[] proj=new double[16]; 
  double[] model=new double[16]; 
  gl.glGetIntegerv(GL.GL_VIEWPORT, viewport, 0); 
  gl.glGetDoublev(GL.GL_PROJECTION_MATRIX,proj,0); 
  gl.glGetDoublev(GL.GL_MODELVIEW_MATRIX,model,0); 
  FloatBuffer fb=ByteBuffer.allocateDirect(4).order(ByteOrder.nativeOrder()).asFloatBuffer(); 
  gl.glReadPixels(mouseX, height-mouseY, 1, 1, GL.GL_DEPTH_COMPONENT, GL.GL_FLOAT, fb); 
  fb.rewind(); 
  double[] mousePosArr=new double[4]; 
  glu.gluUnProject((double)mouseX,height-(double)mouseY,(double)fb.get(0), model,0,proj,0,viewport,0,mousePosArr,0); 
  ((PGraphicsOpenGL)g).endGL(); 
  return new float[] {(float)mousePosArr[0],(float)mousePosArr[1],(float)mousePosArr[2]};
}