Я нашел способ, используя fillRect
:
Shape rectangle = null;
Image groundTexture = new Image("res/grassMid.png");
//parameters are x position, y position, width, height, image, offsetX, offsetY
g.fillRect(0.0f, Window.HEIGHT * 5.3f / 6.0f, (float) Window.WIDTH, Window.HEIGHT / 8.0f, groundTexture, 50, 0);