As far as I read, I remember sex and nudity being described in ancient texts (thinking of the Bible or accounts from the fist Europeans to arrive in the new world) with special care of not being overly explicitly nor vulgar.
Now, how was sex recorded in other cultures in the ancient times? Would you have examples of accounts that would be significantly more "straight to the point"?
What other cultures or times are you most interested in? As it stands, the question if rather broad, and you're not inviting many good detailed answers.