what is 2-D and 3-D composition ,tell me how I will do good composition by given 3-D object.?

Answer 1

Well, since you are asking in drawing, we have to assume you want to make a 2D drawing of a 3D object. At a minimum you wish to turn the (small) object or walk around the (large) object so that you see the changing shape and profile as well as the shadows. Then you will have to decide whether you are composing in isolation - a drawing floating in the middle of the paper - or you are creating an overall composition where you have to draw a background or adjacent details (a still life if small or landscape if large) and how to balance those using the rules of 2D composition