Re: Bounding box of a set of points... - C / C++ / MFC Discussion Boards

Cedric Moonen23-Aug-04 1:20

23-Aug-04 1:20

I don't think such a function exists... but why don't you write it yourself ??
You just have to search the minimum and maximum of all the x coordinates and the minimum and maximum of all the y coordinates. This will give you the 4 boundaries of your box. (Of course, you can apply this for 3d so search also the min & max of the z coordinates).

Hope this helps

Re: Bounding box of a set of points...

Anonymous23-Aug-04 2:32

Anonymous

23-Aug-04 2:32

You just have to....
thanks cedric, but I need this function during the next 24 hours...so I'm a little bit in a hurry....

Re: Bounding box of a set of points...

Maximilien23-Aug-04 2:46

Maximilien

23-Aug-04 2:46

god, it takes ONLY 5 minutes to write ...

one big loop and some comparisons ....

Maximilien Lincourt
Your Head A Splode - Strong Bad

Re: Bounding box of a set of points...

Cedric Moonen23-Aug-04 2:55

Cedric Moonen

23-Aug-04 2:55

typedef struct<br />
{<br />
    float X;<br />
    float Y;<br />
    float Z;<br />
}  3DPOINT;<br />
<br />
void Boundary(3DPoint* pPointsArray, int Count, int &XLow, int &XHigh, int &YLow, int &YHigh, int &ZLow, int &ZHigh)<br />
{<br />
XLow = XHigh = pPointsArray[0].X;<br />
YLow = YHigh = pPointsArray[0].Y;<br />
ZLow = ZHigh = pPointsArray[0].Z;<br />
<br />
for (int i=0;i<Count;i++)<br />
{<br />
if (pPointsArray[i].X < XLow)<br />
XLow = pPointsArray[i].X;<br />
if (pPointsArray[i].X > XHigh)<br />
XHigh = pPointsArray[i].X;<br />
<br />
//The same for Y and Z coordinates<br />
}<br />
<br />
}

Anonymous wrote:
thanks cedric, but I need this function during the next 24 hours...so I'm a little bit in a hurry....

I don't think this takes sooooooooooo much time to do something like that Poke tongue | ;-P

Re: Bounding box of a set of points...

Anonymous23-Aug-04 3:23

Anonymous

23-Aug-04 3:23

ok i see now what you wanted to do....thanks a lot cedric...but I think that your technic is not optimal...
With your technique the bounding box will change if you work in an another reference, do you understand ???
I want a function that will minimize the volume and enclosing the different points .....

Re: Bounding box of a set of points...

Maximilien23-Aug-04 3:30

Maximilien

23-Aug-04 3:30

it will never be really optimal, unless the points are already partially sorted.

reference ? what do you mean ? orientation and POV ?

Maximilien Lincourt
Your Head A Splode - Strong Bad

Re: Bounding box of a set of points...

Anonymous23-Aug-04 3:35

Anonymous

23-Aug-04 3:35

the reference that you use for the coordinates of your points....

Re: Bounding box of a set of points...

Cedric Moonen23-Aug-04 3:30

Cedric Moonen

23-Aug-04 3:30

Anonymous wrote:
With your technique the bounding box will change if you work in an another reference, do you understand ???

D'Oh! | :doh:

Errrrr... Nope, not really Confused | :confused:

. If you change your reference, just modify the boundings so this will follow your new reference...

Anonymous wrote:
I want a function that will minimize the volume and enclosing the different points .....

But that's what it's doing: including ALL the points with the MINIMUM volume. Or did you want something else ?? Then ask a more specific question because for me that is exactly what you asked for... If you want to include all the points this is really the only solution to have the minimum volume !!

Re: Bounding box of a set of points...

Anonymous23-Aug-04 3:42

Anonymous

23-Aug-04 3:42

I'm not sure that you alwalys obtain the minimum volume....just try to imagine with a specific example...with points which are the corners of a rotate box...if you try to enclose the 8 corners with your technic, you don't obtain the same box...

Re: Bounding box of a set of points...

Maximilien23-Aug-04 4:04

Maximilien

23-Aug-04 4:04

if your points coordinates change, you need to update the bounding box.

Maximilien Lincourt
Your Head A Splode - Strong Bad

Re: Bounding box of a set of points...

Cedric Moonen23-Aug-04 4:15

Cedric Moonen

23-Aug-04 4:15

Ok I understand now better what you want ! Sorry for my misunderstanding Poke tongue | ;-P

.

Ok, but your box has to be a cube, or the faces can be rectangles (don't know how to say this in english Smile | :)

), or can it be a complex polygon (in 3D)?

I think this is a really complex problem Dead | X|

. I don't have the solution but perhaps try something like this: (here is the explanation in 2D, this will be more complex in 3D) choose 2 points and join them by a line. Now for each other point try to draw a perpedicular to this line that join the point. From all these lines, just keep the two that will 'enclose' the rest of the points. And now try to find the last line that will close your rectangle..
You'll have to do this for every couple of points and calculate the resulting area of each rectangle and then keep the minimum one... Ufff, already very complex in 2D, in 3D it will be much more complex !!

I don't know this is just a suggestion...

Re: Bounding box of a set of points...

Antony M Kancidrowski23-Aug-04 3:26

Antony M Kancidrowski

23-Aug-04 3:26

If you are really getting so depressed with programming then perhaps a new line of work would be a better solution. Life is too precious Rose | [Rose]

Ant.

I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Williams (Little Britain)

Re: Bounding box of a set of points...

Antony M Kancidrowski23-Aug-04 4:18

Antony M Kancidrowski

23-Aug-04 4:18

Perhaps this may help

http://citeseer.ist.psu.edu/context/342141/0[^]

or a look on Google with "Finding minimal enclosing boxes" as the subject.

Ant.

I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Williams (Little Britain)

CHexEdit search problem (MFC)

evrenpredator23-Aug-04 0:51

evrenpredator

23-Aug-04 0:51

Hello Everybody here is my problem...

-> inside header file:
...
CHexEdit HexEdit;
...
-> inside cpp file: i read hex data from a file and add it to HexEdit
...
HexEdit.SetData(arr, 0);
...

->up to now i have no problem. I can view or edit the hex code and I can save it to another file without any problem.

---> my question is how can i find hex characters inside this HexEdit. for example i write "EE" to an edit box and a find button sets HexEdit scroll to first "EE" than second etc. or highlight the first "EE"...
---->İs there a CHexEdit method to find that character in data(like string.find(string)), or something else???

thanks...

BYE&SMILE Smile | :)

EvrenPredator;)

Re: CHexEdit search problem (MFC)

Antony M Kancidrowski23-Aug-04 3:10

Antony M Kancidrowski

23-Aug-04 3:10

Question, what is CHexEdit?
Is it a control you created or a third party control that you bought?

Ant.

I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Williams (Little Britain)

Re: CHexEdit search problem (MFC)

David Crow23-Aug-04 3:26

David Crow

23-Aug-04 3:26

evrenpredator wrote:
CHexEdit HexEdit;

Are you referring to this class? If so, the author's profile is here. Try sending him an e-mail to see if the class will do what you require.

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

Re: CHexEdit search problem (MFC)

evrenpredator23-Aug-04 23:05

evrenpredator

23-Aug-04 23:05

Yes exactly that class, I have seen that before it is very usefull and it gives me an idea for doing it in another way and solve my problem. but still I look for getting the data in Hex Edit.

Previous question: CHexEdit is the activeX control on MFC Dialog Based application. (by left click dialog box than insert activeX control than hexEdit Control)

thanks for your replies...

Re: CHexEdit search problem (MFC)

David Crow25-Aug-04 5:22

David Crow

25-Aug-04 5:22

Nothing remotely related to CHexEdit shows up in that list for me.

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

How To Find Out Where My Programm is Placed

Rassul Yunussov22-Aug-04 23:55

Rassul Yunussov

22-Aug-04 23:55

Actually i want my programm to collect files in special directory, for example "c:\MyProgramm\Data", and my exe is in "c:\MyProgramm". But if someone canges the full path, where my programm placed?? For example:"c:\Program Files\MyProgramm\\"??? How to alway know where is the Application?

Re: How To Find Out Where My Programm is Placed

Michael P Butler23-Aug-04 0:37

Michael P Butler

23-Aug-04 0:37

CString strApplicationDir;
char szPath[_MAX_PATH];
GetModuleFileName(NULL, szPath, _MAX_PATH);
strApplicationDir = szPath;
int nPos = strApplicationDir.ReverseFind('\\');
if (nPos != -1)
    strApplicationDir = strApplicationDir.Left(nPos);

Michael

CP Blog [^]

Re: How To Find Out Where My Programm is Placed

David Salter23-Aug-04 0:39

David Salter

23-Aug-04 0:39

You can place your data files relative to where your application is installed so then it doesn't matter wher a user puts your app.

Have a look at the GetModuleFilename() method - this will give you the full path to your exe.

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/base/getmodulefilename.asp[^]

store your internet favourites online - www.my-faves.co.uk

"Random Access" writing to files

Jon Hulatt22-Aug-04 22:16

Jon Hulatt

22-Aug-04 22:16

Hi All,

How can I write to a file with random access, ie- be able to change data at any point in the file, not just append new data at the end?

I'm sure this must be possible, if you could give me a starter point / keyword i'm sure i'll be able to find the rest myself!

I don't want to "simulate" this by read/modify/write the whole file, because the files i need to modify will be in the 100's of megabytes!.

Thanks

Jon

#include <beer.h>

Re: "Random Access" writing to files

David Salter22-Aug-04 22:27

David Salter

22-Aug-04 22:27

This may do what you want (http://www.codeproject.com/system/cfile64.asp)

In particular look at the Seek() function.

If you're not interested in files this big, have a look at the CFile class in MFC and in particular the Seek() function.

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Re: "Random Access" writing to files

Jon Hulatt22-Aug-04 22:49

Jon Hulatt

22-Aug-04 22:49

OK, I've now figured this out.

Is there a way to insert data into the middle of a file? rather than overwrite it?

Thanks

#include <beer.h>

Re: "Random Access" writing to files

David Salter22-Aug-04 23:36

David Salter

22-Aug-04 23:36

Not easily I'm afraid.

You need to get a copy of the data from the insertion point to the end of the file, insert your new data and then put back the rest of the file.

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