In this house the following strategy can work sometimes: You sit down on the 3 inch in front that the sleeping cat does not cover.
Cat: looks slightly aggressive but prefers to go back to sleep. Then you work your way backwards inch by inch until sleeping cat decides you are coming to close.
This strategy can be helped by starting to give scritchies to the cat and telling him what a sweet and lovable guy he is: too much loving gets mine out of the chair rather quickly.

Now is that cruelty with animals?