Reversing equation

I have this:

XPos+(30*CountX)-(CountY*30), YPos+(15*CountY)+(CountX*15)

the first part works out the X and the second part works out the Y coordinate. But how would i reverse the equation to work out the CountX/Y values if i have an X and a Y cooridinate. I'm having trouble because in order to work out what the CountX value is i need to know the CountY and vice-versa.

I have been working on this a week now and it is really starting to trouble me. Is this possible at all?

Thanks
Matt

You can't.
You are trying to get 3 values from 1?. it's not possible.

TOTAL == Xpos + CountX + CountY

I don't know what are you trying to do.
CountX and CountY is like a tab?
why don't store the values in a full string XD

''''Temporal Amount   3digs(val a) + 3digs(val b)
''''---------------------------030 090
TempAmountX = 30090 ' If I have TempAmountX   I can generate TempAmountY and CountX and CountY
Xpos=10
Ypos=45

'in=TempAmountX   out=CountX and CountY
CountX=Int(Left$(Right$("0"+TempAmountX,6),3))/30
CountY=Int(Right$(TempAmountX,3))/30

Print
Print "TempAmountX = "+TempAmountX+" ===> CountX="+CountX+"  CountY="+CountY
Print
Print "XPos+(30*CountX)-(CountY*30)"
Print Xpos+"  + (30*"+CountX+"="+30*CountX+") - ("+CountY+"*30="+CountY*30+") = "+(Xpos+30*CountX-CountY*30)+" <=== REAL TOTAL"
Print
Print "YPos+(15*CountY)+(CountX*15)"
Print Ypos+"  + (15*"+CountY+"="+15*CountY+") + ("+CountX+"*15="+CountX*15+") = "+(Ypos+15*CountY+CountX*15)+" <=== REAL TOTAL"
Print

'TempAmountX = Int(String(30*CountX)+Right$("00"+String(CountY*30),3))
TempAmountY = Int(String(15*CountY)+Right$("00"+String(CountX*15),3))
Print "TempAmountY = "+TempAmountY+" ===> CountX="+CountX+"  CountY="+CountY

'in=TempAmountY   out=CountY and CountX
CountY=Int(Left$(Right$("0"+TempAmountY,6),3))/15
CountX=Int(Right$(TempAmountY,3))/15

Ok sorry i didn't explain it that well.

The first part calculates an X coordinate and the second calculates the Y:

X Co-ord= XPos+(30*CountX)-(CountY*30)
Y Co-ord= YPos+(15*CountY)+(CountX*15)

CountX and CountY are numbers from 0 to n (whole numbers). I use these in a For loop to draw the images i am using.

PosX and PosY are numbers i know. They are just in there so i can move the overall image around the screen.

So if the user clicks on one of the images i need to (using MouseX and MouseY) work out what the CountX, CountY position of the image is.

I hope this makes more sense.

So..

x = (a*30) - (b*30)
y = (a*15) + (b*15)

simplified :

x = (a - b) * 2
y = a + b

The result is :- Coming up After I've had a sleep!

Why can't you have a simple co-ordinate system?

Its for isometric tiles so i have to move they down/side-to-side depending on which row theyre on etc. So it ends up needing both x and y.

Thanks for the simplification. I was building it up bit by bit trying new things to get the right layout so i ended up with pieced together bits of code.

Check out this article, towards the bottom is the equation you are looking for:
http://www.bookofhook.com/Article/GameDevelopment/IsometricEngineDevelopmen.html

Try it!

a=22
b=166

x=(a-b)*2
y=a+b

'------------------

aNew=((x/2)+y)/2
bNew=y-aNew

Thanks for the link altitudems. That helped alot.

Your version didn't seem to work for me though BlackSp1der.