Projectiles with wind

[McCain]

Hi,
I'm trying to make a game like "Gorilla". Don't know if you've ever played it, but you're two players (two gorillas) and you are standing ontop of tall buildings. You are then supposed to throw bananas on each other. You enter the speed and angle of the banana to make it go over the buildings and hit the other gorilla. And there is also wind blowing in different directions all the time that you have to take in count when you decide what angle and speed you're going to use.

I know how to calculate the path of the banana if you don't care about wind. But I have no idea what to do when there is wind blowing. Can anyone help, please?

Currently I have this code (just to see if it'll work)

Private Sub cmdDraw_Click()
    Const pi As Double = 3.14159265358979
    Const g As Double = 9.82
    Dim v As Double
    Dim a As Double
    Dim x As Double
    Dim y As Double
    
    If edtV.Text = "" Or edtA.Text = "" Then
        MsgBox "Nu glömde du igen..."
        Exit Sub
    End If
    
    Me.Cls
    
    v = edtV
    a = edtA
 
    Me.Line (0, 200)-(600, 200)
    CurrentX = 0
    CurrentY = 200
    
    x = 0
    Do
        y = Tan(a * (pi / 180)) * x - g / (2 * v * v * Cos(a * (pi / 180)) * Cos(a * (pi / 180))) * x * x
        Me.Line -(x * 5, -(y * 5) + 200)
        x = x + 1
    Loop Until Tan(a * (pi / 180)) * x - g / (2 * v * v * Cos(a * (pi / 180)) * Cos(a * (pi / 180))) * x * x < -1
End Sub

[SLH]

Not too sure, but try experimenting with this as a formula for y:

Tan(a * (pi / 180)) * (x+W) - g / (2 * v * v * Cos(a * (pi / 180)) * Cos(a * (pi / 180))) * (x+W) * (x+W)


As you see, i've replaced x with x+W. I'm not sure whether this will work, but try giving w different values and see what the curve does.

[DiGiTaIErRoR]

Since you don't use Pi directly you can make the constant pi / 180.

It'll go faster.

[DiGiTaIErRoR]

Also...

'if x = 0 then y = 0
        x = 0
        y = 0
    Do Until y < -1
        Me.Line -(x * 5, -(y * 5) + 200)
        x = x + 1
        y = Tan(a * (pi / 180)) * x - g / (2 * v * v * Cos(a * (pi / 180)) * Cos(a * (pi / 180))) * x * x
    Loop

will make it faster.

[McCain]

DiGiTaIErRoR: Thanks for the speed tips
SLH: Can it realy be that easy? Shouldn't size and weight of the projectile have a factor in how much the wind will affect it?

[SLH]

As you don't have any size/weight variables in your code i assumed that sort of thing didn't matter. I don't know what the modifications would be if you wanted to properly simulate the physics, i was just suggesting a way of doing it without physics.

[McCain]

Ohh, sorry for the misunderstanding.
I didn't add size or weight because I didn't know how to add them to a formula.
I did some searching on the net for a formula that takes wind into the calculation. I found a few but they were all in English and I didn't quite understand them. I couldn't find any in my language (Swedish)...
So I guess this is kinda hard... If any physics experts read this post - please help me.

[DiGiTaIErRoR]

Well.

If a plane is going 200 MPH north, and there's a 100 MPH wind blowing south, the plane goes 100 MPH. If the wind blew south to north, the plane would go 300 MPH.

You have to use trig functions(sin,cos,tan) to calculate for variable degree winds.

[BodwadUK]

You could add a new element

Aerodynamics

[vbNeo]

Originally posted by BodwadUK
You could add a new element

Aerodynamics