Thing_ProjectileGravity

From ZDoom Wiki

136:Thing_ProjectileGravity (tid, type, angle, speed, vspeed)

Spawns a projectile and subjects it to gravity. Note that this special requires the actor being spawned to have a SpawnID. To spawn an actor without one, use the SpawnProjectile function instead.

tid: Thing ID of the map spot to spawn the projectile at 
type: Type of projectile to spawn, from the list of Spawn numbers
angle: Byte angle of the projectile 
speed: Horizontal speed of the projectile in units per tic * 8
vspeed: Vertical speed of the projectile in units per tic * 8 (up is positive)