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-   -   boxToCell versus rotatedBoxToCell (http://www.cfd-online.com/Forums/openfoam-meshing/128013-boxtocell-versus-rotatedboxtocell.html)

 engineer_the December 30, 2013 14:47

boxToCell versus rotatedBoxToCell

Hello,

Inside of topoSet I was using rotatedBoxToCell and was getting an unexpected selection of cells. To clarify I started comparing rotatedBoxtoCell (using non-rotated coordinates) with a simple boxToCell. Can anyone help explain why the two examples below result in two vastly different selections?

Code:

```{     name test;     type cellSet;     action new;     source boxToCell;     sourceInfo     {     box (0.03 0.05 0) (1 1 1);     } }```
versus

Code:

```{     name test;     type cellSet;     action new;     source rotatedBoxToCell;     sourceInfo     {     origin (0.03 0.05 0);     i (1 0.05 0);     j (0.03 1 0);     k (0.03 0.05 1);     } }```

It should be noted that the following definitions give the same selection, which confuses me even more:

Code:

```box (0 0 0) (1 1 1); origin (0 0 0); i (1 0 0); j (0 1 0); k (0 0 1);```

 engineer_the December 30, 2013 15:38

I ended up solving my own problem. The i,j,k vectors are relative to the origin specified, in my example:

box (0.03 0.05 0) (1 1 1);

should be equivalent to

origin (0.03 0.05 0);
i (0.97 0 0);
j (0 0.95 0);
k (0 0 1);

 yourvahid August 6, 2014 14:07

Hi,
If you look at the source code it helps you to get it easier, a part of it that I think is helpful and related to your post is shown below:

Code:

```    boxPoints[0] = origin_;     boxPoints[1] = origin_ + i_;     boxPoints[2] = origin_ + i_ + j_;     boxPoints[3] = origin_ + j_;     boxPoints[4] = origin_ + k_;     boxPoints[5] = origin_ + k_ + i_;     boxPoints[6] = origin_ + k_ + i_ + j_;     boxPoints[7] = origin_ + k_ + j_;```

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