|If you place a glass on a table, its attitude towards you the viewer would be the same as the table. It would look as though it were standing solidly on top of the table top. If you wanted to view the glass form a different attitude you could do one of two things: move yourself (your eyes) towards the glass and at a different point of view, or you could pick up the glass and rotate it to a different position in relation to your point of view. Either of these options would require a different horizon line for the glass.
If you chose to move yourself, both the environment and the glass perspective would change together. If you chose to just move the glass, then the perspective of the environment would remain the same but the glass would require a new horizon line of its own.
|The action chosen:|
|The viewer's perception:|
|This also applies to a cartoon character. If they tilt their head so you see more of the top, then you must apply the rules of perspective to all the features on their head as well or it will look as though their eyes, nose, mouth, ears and hair are floating around on the surface of their head. This would cause a very unpleasant reaction if it were to happen in real life so we should try to avoid it in our drawings as well.