Fling

Flinging is a basic movement skill in both Portal and Portal 2, in which the player converts a downwards kinetic energy from gravity of either himself or an object, to the same energy directed straight up, horizontally or diagonally.

However, there are major differences in how these are handled in both games.

Air control

In Portal, the player can literally bend their flying arc sideways during a fling, about the same way the Demoman or the Soldier do in Team Fortress 2. In Portal 2, there is little to no air control; it is kept to a slight bending, and can be predicted accurately, or be a result of a prediction.

Debugging tools are available in Portal 2 to visualize predicted flinging arcs.Template:How?

In Portal 2, it is no longer possible to crouch-jump into a portal, entering into a portal crouched makes no difference. In Portal, it is possible to enter a floor portal diagonally while crouched to perform special flings, and to fling crouched to reach higher places. In Portal 2, crouching doesn't make a difference, but flinging diagonally is still a possible move if the portal is placed on a diagonal surface, or if the player enters the portal diagonally.

Some of the flings in Portal 2 can be entierely orchestrated without the use of visible Aerial Faith Plates using a trigger_catapult. It is extensively used in places in which the level designer wants to make the player land on a small area, keeping the random factor deaths to a minimum.

Physical props

Props like cubes are handled differently in Portal and in Portal 2. In Portal, it uses about the same system as the gravity gun as the handled prop keeps a lot of its physical properties. In Portal 2, some of the physical properties of the handled prop are sacrificed to allow the player to fling with those props without too much of a problem.

Also, in Portal, it is possible to get killed by colliding with a speeding prop, or by flinging into an immobile prop. In Portal 2, the player takes no damage from physical interaction with props.