import bsh.util.BshCanvas;   // BshCanvas simply buffers graphics

graph( int width, int height ) {
	canvas=new BshCanvas(); 
	canvas.setSize( width, height );
	frame=frame( canvas );
	graphics=canvas.getBufferedGraphics();
	// draw axis
	graphics.setColor( Color.red );
	graphics.drawLine( 0, height/2, width, height/2 );
	graphics.drawLine( width/2, 0, width/2, height );
	graphics.setColor( Color.black );

	plot(int x, int y) {
		graphics.fillOval( (x+width/2-1), (y+height/2-1), 3, 3);
		canvas.repaint();
	}

	return this;
}

drawSin( graph ) {
	for (int x=-100; x<100; x++ ) {
		y=(int)(50*Math.sin( x/10.0 ));
		graph.plot( x, y );
	}
}