Need help calculating a location

[Resin_Smoker]

I've two units with known locations.

What i want to do is use both units locations to create a vector (direction) and then set a new location a specific distance along said vector.

Example:

Unit A Position.
Unit B Position.
New Destination along the same vector a given distance away.

A ------ B -----> D

While i can easily calculate a vector from two points, creating a new destination from said vector and a specified distance has eluded me thus far.

Thanks in advance!

Resin

[IceDreamer]

What do you want help with? Developing the coordinate for D, or actually issuing a command to one of the units?

[ckitching]

Isn't this fairly trivial?

Given a vector from A to B, you can obtain a vector from A to a point beyond B by multiplying it by a scalar.

It's also not quite true that a vector is "a direction": a vector represents both direction and magnitude.

[FunkOff]

Shouldn't this be easy?

Find the difference between the X and Z values for the positions of the units. Use that to calculate the distance. Then calculate two ratios, one for the X value over the distance and one for the Z value over the distance. (These would be called "Sine" and "Cosine" in trigonometry). Then pull whatever your set distance between unit B and position D is (I assume it's a fixed value?) and multiple these ratios times the set distance, and you have your X and Z position deviations from unit B.

[Vee]

Define unit(v) = v/sqrt(v.x^2 + v.y^2 + v.z^2). The position you want is B + unit(B-A)*given_distance.

[Resin_Smoker]

The problem is with the specified distance not meeting my expectations.

Resin

[Myxir]

there is a lua/utilities.lua, should be helpful

something like this might work

Code: Select all

A + NormalizeVector( GetDirectionVector( v1, v2 ) )*length


[Resin_Smoker]

Here is what I've written thus far...

This not only gets the entities at the location but also validates and sorts entities by range.

Any suggestions?

Note: This will be used for the chain-lightning revamp.

Resin

---Code---

Spoiler: show

Code: Select all

   GetValidTargetsAlongScaledVector = function(self, entity1, entity2, scale)
      if self.BeamDebug then WARN('GetValidTargets') end
      local posV1 = entity1:GetPosition()
      local posV2 = entity2:GetPosition()
      local modPos = utilities.GetScaledDirectionVector( posV1, posV2, scale )
      if self.BeamDebug then
         WARN('modPos x: ', modPos[1],'modPos y: ', modPos[2],'modPos z: ', modPos[3])
      end
      local targets, targByDist = {}
      local targets = GetEntitiesInRect( Rect(modPos[1] - scale, modPos[3] - scale, modPos[1] + scale, modPos[3] + scale) )
      if targets == nil or table.getsize(targets) < 0 then return nil end
      for a, b in targets do
         if not b:BeenDestroyed() and b:GetHealth() > 0 then
            table.insert(targByDist, {dist = utilities.XZDistanceTwoVectors(posV1, b:GetPosition()), unit = b})
         end
      end
      table.sort(targByDist, sort_by('dist'))
      if self.BeamDebug then
         for c, d in targByDist do
            WARN('    Unit: ', d:GetEntityId(), ' Distance: ', utilities.XZDistanceTwoVectors(posV1, d:GetPosition()) )
         end
      end
      return targByDist
   end,

[Legion Darrath]

Moved to mods.

[Resin_Smoker]

Moved to mods.

Gee thanx for the assist... No idea what the world would of done with you at that moment in time. (sarc)