Here are some of my thoughts on the use of curves in maps:
Let take a simple example of a room
with two exits (or two entrances, your pick)
I have circled all the camp spots which dont really add any thing to the gameplay. Also i feel square rooms are boring and dont direct the flow of gameplay very well.
Lets look at the same room with some curves put in:
Here all the camping spots are eliminated, the flow through that area has improved (the player model will not get stuck or jammed when trying to navigate the area whilst running backwards), and imo is more pleasing to the eye. Another important thing is that curves can draw your eye to certain parts of the area, look at fig1 and then fig2 and 3. You will notice that your eyes are drawn to the entrances/exits much quicker in fig2 and 3 than in one, this allows the player to come into a new environment whilst under pressure and quickly spot the important features (in this case exits/entrances) .
In games that feature strafe jumping, rocket jumping, projectiles and bouncing grenades, curves generally make these features more satisfying. As projectiles and players can move/bounce round areas a lot easier instead of stopping dead in a corner and losing speed. This makes curves great for choke point in the map, where a lot of action can be happening at once. Corners and clipping issues can cause a lot of frustration for the player under fire while in choke points.
Look at this choke point on the map ‘cp_gullywash_pro’ for tf2:
I circled the two curves that help improve flow through choke. If your in this area and retreating you will be receiving alot of spam (rockets, nades etc), so you will (if your a good player) be facing the action as you retreat- the curves help you get out of the choke easily and provide consistent splash-back from oncoming nades/rockets.
Games like quake use curves to help maintain player speed (or even increase it in games like Warsow!) :
not only does the curve on the back wall (fig5) help maintain players speed when strafe jumping/rocket jumping through the area, it also helps centralize the action (center part of map in behind inner wall). If straight walls where used here the players path would be similar to the blue line- bringing him further away from the action and creating a camp spot high up on the map in the corner.
To sum up, curves can:
- Make areas flow better
- Reduce camping spots
- look more pleasing to the eye
- Help centralize action
- Decrease player clipping