# Using Pi and Arcs for a Radar

Shows you how to use Pi for drawing Arcs(part of a circle) to use as a radar.

**Original Author:** Philip Salmony

### Code

`Using Pi and Arcs for a Radar`

Hi, I'm Philip and I'm going to show you to how to make a great radar for games or other stuff.

So...the first thing you need to know is what Pi is ! Pi is a number to calculate stuff with circles. Pi goes on for EVER !!! But of course we only need a few digits :

Pi = 3.14159265358979 (we need a double data type for that!)

You will need to put a Timer (called RadarSearcher) and a PictureBox (called

RadarBox) on the Form .So now we need to declare the globals (Pi and the Arcsize(in degrees)). So just type this

in :

'Globals for radar

Const PI As Double = 3.14159265358979

'We need Pi for calculating where the arc should be and at

what angle

Const ARCSIZE As Integer = 45

'Lets take an arc of 45 degrees size

Then we need to create the sub for the Timer. This is the main part (the

core) of the program which calculates and displays the radar. Once you've typed

the next block of code in set the Enabled property of the Timer to true (which

is actually the defaut, but just making sure) and the Interval property of the

Timer to 100. Having the Interval property at 100 makes the Radar look

smooth-running. If you want to you can set the Interval property to 1000 and see

what happens. So enough of the boring stuff... Let's get down to business :

'Timer Sub for calculating and displaying the radar

Private Sub RadarSearch_Timer() 'The main Timer (Interval set 100 is

standard)

Dim X As Integer, Y As

Integer, r As Integer 'X

and Y Coordinates of the Arc

Dim ArcStart As Single, ArcEnd As Single

'The beginning position of the Arc (in degrees)

Dim nCount As Integer 'Main

loop variable (used to move the arc)

'Make sure that the forecolor is vbRed and the backcolor is vbBlack ! I tried

using a different color combination and it didn't display anything !!!

RadarBox.FillColor = vbRed

RadarBox.BackColor = vbBlack

'The

next 3 lines make the arc fit into the PictureBox perfectly

X = RadarBox.ScaleWidth - 4

Y = RadarBox.ScaleHeight - 4

r = X / 2

'The next 4 lines set the drawmode stuff and

draw a circle (NOT AN ARC) for the arc to move in

RadarBox.DrawWidth = 1

RadarBox.DrawMode = vbCopyPen

RadarBox.FillStyle = vbFSTransparent

RadarBox.Circle (X / 2 + 2, Y / 2 + 2), r

'These next 2 lines also do some drawmode

stuff

RadarBox.DrawMode = vbXorPen

RadarBox.FillStyle = vbSolid

'Now... the big one ! This rotates and draws the arc 1

full rotation.

For nCount = 0 To 360

ArcStart = nCount

ArcEnd = nCount + ARCSIZE

If ArcEnd > 360

Then ArcEnd = ArcEnd - 360

RadarBox.Circle ((X / 2) + 2, (Y / 2) + 2), r, , -ArcStart * PI / 180, -ArcEnd * PI / 180

DoEvents

RadarBox.Circle ((X / 2) + 2, (Y / 2) + 2), r, , -ArcStart * PI / 180, -ArcEnd * PI / 180

Next nCount

End Sub

I really hope you liked this tutorial. If you did please vote for me.

Philip

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