qzdoom/wadsrc/static/zscript/shared/fastprojectile.txt

// Fast projectiles --------------------------------------------------------

class FastProjectile : Actor native
{
	Default
	{
		Projectile;
		MissileHeight 0;
	}
	
	
	virtual void Effect()
	{
		class<Actor> trail = MissileName;
		if (trail != null)
		{
			double hitz = pos.z - 8;

			if (hitz < floorz)
			{
				hitz = floorz;
			}
			// Do not clip this offset to the floor.
			hitz += MissileHeight;
			
			Actor act = Spawn (trail, (pos.xy, hitz), ALLOW_REPLACE);
			if (act != null)
			{
				if (bGetOwner && target != null)
					act.target = target;
				else
					act.target = self;
				
				act.angle = angle;
				act.pitch = pitch;
			}
		}
	}
	
}