HELP! calculating vector components [RESOLVED]

[Arachnid13]

hi... i know this has been asked before but i haev spent the last half an hour searchin the forums for the answer.. basically does anyone have some code which you can use to turn two points (x1,y1),(x2,y2) into a vector, basically i want to find the direction from object 1 to object 2 in a vector form (assume the magnitude=1) and i know you need a different equation depending on which quadrant its in (0-90,90-180 etc) but i cant figure it out any help would b much appreciated

[wossname]

Hope this is what you want.



Vector from A to B

= ( 9 - (-12) , 20 - (-10) )

In other words...

(Destination.X - Start.X, Destination.Y - Start.Y)

This example would give you (21, 30).

To get your unit vector, divide both x and y by the magnitude...

Mag = Sqrt(21^2 + 30^2)

x = 21/mag
y = 30/mag

Giving you a unit vector of (0.57346, 0.81923), new magnitude = 1.

(It doesn't matter what quadrants the points are in )





Gurus: If I have got this wrong, please let me know because i'm not a math god

[opus]

Hi Arachnid13, did you get what you need? Or do you also need the direction in degrees? Let us know

[opus]

Found the routine I'm using

Public Const Pi = 3.141592654
Public Const PiDurch180 = Pi / 180
Public Const A180DurchPi = 180 / Pi
Public Function Bearing(x1, y1, x2, y2) As Single
'Input X1, Y1, X2, Y2
Calculates Bearing(0-360)
'Calculates from X1,Y1 to X2,Y2  in 360degree-system
'North, Y , Lat gets bigger!!!!
'East X, Long gets bigger!!!!!
Dim dx As Single
Dim dy As Single
dx = x2 - x1
dy = y2 - y1
If dy <> 0 Then
        Bearing = (Atn(dx / dy) * A180DurchPi)
        If x2 > x1 Then
                If y2 > y1 Then
                        Bearing = Bearing
                Else
                        Bearing = 180 + Bearing
                End If
        Else
                If y2 > y1 Then
                        Bearing = 360 + Bearing
                Else
                        Bearing = 180 + Bearing
                End If
        End If
Else
        If x1 > x2 Then
                Bearing = 270
        Else
                Bearing = 90
        End If
End If
End Function

[Arachnid13]

thanks guys, both are very useful, the second post was what i meant but ive just realised i can do what i needed with the first one and its much simpler... should have thought of it before... thanks!

[wossname]

No worries