Another vector help thread

**dpidcoe** · 11-27-2008

I made a turret that'll point at a target using vector thrusters (basically a bar with a negative mult on one end and and positive mult on the other). The eventual goal is to stick it on a spaceship where it can cover a 180 degree bubble, a similar turret on the reverse side will cover the other half.

I want it to work so it points along the axis of the ship if the target is outside of the 180 bubble, and point at the target if it can hit it. I can make it point along the ships axis just fine, but where I'm running into problems is on how to tell if it'll intersect with the ship.

Currently I have the vector of the ship and the vector to the target to work with. Heres a picture of what I'm talking about:

**Magos Mechanicus** · 11-27-2008

One fairly easy way to do this is to find a vector that is always normal to the ship wall. For instance, you can place an E2 gate on the wall and use its entity():up() vector. Then you take the vector from the turret to the target and project it onto that normal vector. If the projection has a positive length, the target is inside that hemisphere.

Code:

Normal=entity():up()#Or some other one you find.
Projlength=Totarget:dot(Normal) 
#The vector projection is Projlength*Normal, but we only really need the length
if(Projlength>0){Target normally}else{Face forward}