LookAt function (C++)

[george68]

Hi,

I need a function that rotates an entity in order to turn and look at another one.

So far I have calculated the vector from the source to the destination entity but I don't know how to calculate the pitch, yaw and the roll of the vector.

Any assistance will be appreciated.

[Brutile]

You could always just use this http://www.leadwerks.com/werkspace/page/api-reference/_/entity/entitypoint-r167

[george68]

Thanks. This is what I was looking for.

But I still want to implement a custom function because I want the transition take place smoothly.

[Einlander]

This is what I found when I was programming something. it also has resources and sources I used linked

 

function Script:LookAt(start,target)
   --http://www.leadwerks.com/werkspace/topic/10191-short-example-of-mathatan2/page__hl__lookat
   --http://stackoverflow.com/questions/1251828/calculate-rotations-to-look-at-a-3d-point
   --http://leadwerks.wikidot.com/wiki:face-entity

   --// Calculate angle from point A towards point B
   local tv = (target - start) 

   local tRoty = Math:ATan2(tv.x, tv.z)
   --local tRotx = 
   if tv.z >= 0 then    
       tRotx = -Math:ATan2(tv.y* Math:Cos(tRoty), tv.z)
       else    
       tRotx = Math:ATan2(tv.y* Math:Cos(tRoty), -tv.z)
   end
   tRotz = Math:ATan2( Math:Cos(tRotx), Math:Sin(tRotx) * Math:Sin(tRoty) )
   return Vec3(tRotx,tRoty,tRotz-90)
end

[Brutile]

Parameters

 

• entity: the target entity to point towards.
  
• axis: the entity's axis to orient. This may be 0, 1, or 2, for the X, Y, and Z axes, respectively.
  
• rate: a multiplier to indicate how quickly the entity should orient itself.
  
• roll: the rotation around the specified axis.
  

[george68]

@Einlander: Thanks. I'll take a look at your snipped.

@Brutile: I missed this parameter. I suppose that I have to call this function from within the update loop and call 3 times (one for each axis)