# Calculate Angles from the coords of three points

Email
 Submitted on: 1/6/2015 5:16:00 PM By: Kevin Laity (from psc cd) Level: Intermediate User Rating: By 3 Users Compatibility: VB 4.0 (16-bit), VB 4.0 (32-bit), VB 5.0, VB 6.0 Views: 1396

This code is useful in games where you need to calculate an angle quickly. Using three points it gives you the angle, in degrees, of the vertex.

code:
Can't Copy and Paste this?
 ``` '************************************** ' Name: Calculate Angles from the coords of three points ' Description:This code is useful in games where you need to calculate an angle quickly. Using three points it gives you the angle, in degrees, of the vertex. ' By: Kevin Laity (from psc cd) ' ' Inputs:Three sets of coordinates: A center point, and the ends of two lines coming from the center. ' ' Returns:The angle of the vertex in degrees '************************************** Function LineLen(x1, y1, x2, y2) 'This function will simply give you the length 'of a line using the coordinates of its two 'endpoints. Dim A, B As Single A = Abs(x2 - x1) B = Abs(y2 - y1) LineLen = Sqr(A ^ 2 + B ^ 2) End Function Function Arccos(X As Single) If X = 1 Then Arccos = 0: Exit Function Arccos = Atn(-X / Sqr(-X * X + 1)) + 2 * Atn(1) End Function Public Function CalcAnAngle(CenterX, CenterY, x2, y2, x3, y3) 'This function will take three coordinates and 'automagically turn them into an angle. 'The angle is the one located at CenterX, CenterY 'For example: '/ X2,Y2 '/ ' / ' < CenterX,CenterY ' ' '\ X3,Y3 'CalcAnAngle will return the angle, in degrees, 'of the center vertex. On Error Resume Next Dim SideA, SideB, SideC As Single SideC = lineLen(CenterX, CenterY, x2, y2) SideB = lineLen(CenterX, CenterY, x3, y3) SideA = lineLen(x3, y3, x2, y2) a = Arccos((SideA ^ 2 - SideB ^ 2 - SideC ^ 2) / (SideB * SideC * -2)) CalcAnAngle = a * (180 / 3.141) 'VB seems to like to work in confusing units 'called Radians instead of good ol' degrees. 'Multiplying by (180 / 3.141) converts radians 'to degrees. End Function```

Use this form to tell us if this entry should be deleted (i.e contains no code, is a virus, etc.).
This submission should be removed because:

What do you think of this code (in the Intermediate category)?
(The code with your highest vote will win this month's coding contest!)
Excellent  Good  Average  Below Average  Poor (See voting log ...)