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# Need help with rewriting loop

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2 replies to this topic

### #1BytePtr  Members

Posted 18 August 2012 - 03:25 PM

Hi.

I got a bit strange problem. Im using OpenGL and raypicking.
But this problem has more coding problem than OpenGL problem.

I have a loop (3D):
[source lang="cpp"] int c = 0; for (int x = 0; x < maxx; x++) { for (int y = 0; y < maxy; y++) { for (int z = 0; z < maxz; z++) { obj[c].Shift(new Vec3(x, y, z)); c++; } } }[/source]

In this loop vertices of objects are shifted according to their positions on the map.
maxx, maxy, maxz are int values. For example:

maxx=3;
maxy=3;
maxz=3;

If they all are equal, like above, then i get fine results and picking works. As soon as at least one of them is different (bigger or smaller), the picking fails to return correct coords (X,Y,Z).
In my case, maxx, maxy, maxz, never can be equal.

MaxX is maximum 255
MaxY is maximum 255
MaxZ is maximum 7

But in that case, code fails to do picking.
If im correct, the problem is in this 3D for loop.

Because if i manually assign coords to objects, the it always works. Even with different maxx, maxy and maxz.

The output of looping is like this:
X: 0 Y: 0 Z: 0
X: 0 Y: 0 Z: 1
X: 0 Y: 0 Z: 2
X: 0 Y: 1 Z: 0
X: 0 Y: 1 Z: 1
X: 0 Y: 1 Z: 2
X: 0 Y: 2 Z: 0
X: 0 Y: 2 Z: 1
X: 0 Y: 2 Z: 2
X: 1 Y: 0 Z: 0
X: 1 Y: 0 Z: 1
X: 1 Y: 0 Z: 2
X: 1 Y: 1 Z: 0
X: 1 Y: 1 Z: 1
X: 1 Y: 1 Z: 2
X: 1 Y: 2 Z: 0
X: 1 Y: 2 Z: 1
X: 1 Y: 2 Z: 2
X: 2 Y: 0 Z: 0
X: 2 Y: 0 Z: 1
X: 2 Y: 0 Z: 2
X: 2 Y: 1 Z: 0
X: 2 Y: 1 Z: 1
X: 2 Y: 1 Z: 2
X: 2 Y: 2 Z: 0
X: 2 Y: 2 Z: 1
X: 2 Y: 2 Z: 2

Im not even sure, if somebody understands this and can help me, but it's pretty strange problem here.
Manually it works, but with this loop, it doesn't.

I will try once more manually, and will try to post differences, but in meanthime i would be thankful to get any help on this.

EDIT: ok my manual values:
0, 0, 0
0, 1, 0
0, 2, 0
0, 0, 1
0, 0, 2

Edited by BytePtr, 18 August 2012 - 03:33 PM.

### #2ApochPiQ  Moderators

Posted 18 August 2012 - 05:13 PM

My guess is that you want this:

0, 0, 0
1, 0, 0
2, 0, 0
0, 1, 0
0, 2, 0
0, 0, 1
0, 0, 2

If that's correct, you need to rearrange your loops a bit. Right now you're looping on Z maxZ times for every time you loop on Y, and you're looping on Y maxY times for every time you loop on X.

This should do what you want:

int c = 0;
obj[c].Shift(new Vec3(0, 0, 0));

for (int x = 1; x < maxX; ++x)
{
++c;
obj[c].Shift(new Vec3(x, 0, 0));
}

for (int y = 1; y < maxY; ++y)
{
++c;
obj[c].Shift(new Vec3(0, y, 0));
}

for (int z = 1; z < maxZ; ++z)
{
++c;
obj[c].Shift(new Vec3(0, 0, z));
}

Wielder of the Sacred Wands

### #3BytePtr  Members

Posted 19 August 2012 - 06:10 AM

Thanks, that was it. Works fine now.
I don't know how i missed that little thing.

EDIT: i probably shouldn't code at 4 AM, without sleeping.

Edited by BytePtr, 19 August 2012 - 06:12 AM.

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