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Angle of 2 points according to right

Posted on 2003-11-02
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Last Modified: 2013-12-26
Hi, I need a function(VB) or a formula for calculating the angle of 2 points according to right, in 2d. I have a standing position(X, Y) and I have a looking position(X, Y) and I want to get the angle from right to the looking position.

Thanks in advance.

 - Julian
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Question by:JulianS
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Accepted Solution

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JulianS earned 0 total points
ID: 9693761
I found the solution myself. The solution is to make a triangle with a side on 90*, then you use one of these 2 formulas(Depending on the triangle):

***
Angle = ArcTan(DifferenceX / DifferenceY)

Or

Angle = ArcTan(DifferenceY / DifferenceX)
***

and then you just add: 0, 90, 180 or 270 to the results(also depending on the triangle position)

Here is the VB function of the algorithm:

***

Function GetAngleFromPosition(StandingPositionX As Double, StandingPositionY As Double, LookingPositionX As Double, LookingPositionY As Double) As Double
 If StandingPositionX < LookingPositionX Then
  If StandingPositionY < LookingPositionY Then
   GetAngleFromPosition = (ArcTan(((StandingPositionY - LookingPositionY) / (StandingPositionX - LookingPositionX))))
  Else
   GetAngleFromPosition = (ArcTan(((StandingPositionX - LookingPositionX) / (StandingPositionY - LookingPositionY)))) + 90
  End If
 Else
  If StandingPositionY < LookingPositionY Then
   GetAngleFromPosition = (ArcTan(((StandingPositionY - LookingPositionY) / (StandingPositionX - LookingPositionX)))) + 270
  Else
   GetAngleFromPosition = (ArcTan(((StandingPositionX - LookingPositionX) / (StandingPositionY - LookingPositionY)))) + 180
  End If
 End If
End Function

'You need this function to convert radians from Atn to Degrees
Function ArcTan(x As Double) As Double
ArcTan = Atn(x) * (180 / 3.14159265358979)
End Function
***

If you are searching for more formulas like this one go to my web at:

http://www.hostinganime.com/3ddev/
 
- Julian
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Author Comment

by:JulianS
ID: 9779681
Thanks

- Julian
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