C / C++ / MFC

21-Jan-07 23:06

I think the problem lies with the resource file being used.. As the dialogue template is in your DLL, where as your main app searches the template in its own resources and consequently dont find anything Smile | :)

.. Try using the dll's resources Smile | :)

.. try using the FindResource(..) function and then creating the dialogue from the template returned by the function Smile | :)

.. I hope it helps Smile | :)

enjoy.

Rotation

Waldermort21-Jan-07 21:45

21-Jan-07 21:45

I would ask this question on the algorithms/maths board, but I feel it is more appropriate here.

Lets say I have 2 points, { X1,Y1 } and { X2,Y2 }, I want to calculate the rotation of #2 around #1 given a number of degrees. What is the fasted possible way to do this in C++?

Here is my method, which I find to be too slow.

X2 = X1 * cosf(rotate) - Y1 * sinf(rotate);<br />
Y2 = X1 * sinf(rotate) + Y1 * cosf(rotate);

softwaremonkey21-Jan-07 21:54

softwaremonkey

21-Jan-07 21:54

You code calculates cosf() and sinf() twice - you could probably speed things up by almost 2 x by only calculating cosf(rotate) and sinf(rotate) once and assigning the values to local variables.

Hope this helps

Tony

nutkase21-Jan-07 23:11

21-Jan-07 23:11

As calculating cosines and sines is expensive, another optimization could be to just calculate them once and make a table for the values ( may in application startup ) this will considerably increase the speed Smile | :)

. If you are rotating these values multiple times. A question you might ask is but the value for the angle could be infinte and hence the table size. The catch here is every angle's cosine/sine is equal to an angle b/w 0-180 (0-pie).. so pratically you need only a table of 180 entries Smile | :)

.

I hope this help!
enjoy

Waldermort21-Jan-07 23:34

21-Jan-07 23:34

Thats an excellent idea, thanks for that.

nutkase22-Jan-07 1:15

22-Jan-07 1:15

The pleasure is all mine :->

softwaremonkey21-Jan-07 23:48

softwaremonkey

21-Jan-07 23:48

Nutkase is right, this method can dramatically improve performance but is only suitable if you can live with integer angle values (every degree) since these will be used directly as indexes into the look-up tables.

If you need finer resolution than 1 degree you could consider having table entries every 0.1 degree but you would need to scale the angles to ensure that you have integral values e.g. 15. degrees would be index 15 in the table.

Naturally the tables would be 10 times bigger i.e. 1800 entries (actually you could get a way with storing values for only 90 degrees

Wink | ;)

Waldermort22-Jan-07 1:24

22-Jan-07 1:24

softwaremonkey wrote:
only suitable if you can live with integer angle values (every degree)

Thats no problem in this instance.

The major problem I am having at the moment is when placing the rotation code inside a loop, where the point being rotated is constantly being refreshed.

Here is a slightly faster method I have tried to adapt.

FPOINT Rotate( float px, float py, float ox, float oy, int a )
{
    //////////////////////////////////////////////////////////////////////////
    // Rotate point 'p' about point 'o' given 'a' degrees
    //////////////////////////////////////////////////////////////////////////

    float s = ( PI * a ) / 180;  // radians

    FPOINT q = { px, py };

    if ( px == ox && py == oy ) {
        return q;
    }

    float r;

    if ( px == ox ) {
        if ( py > oy ) {
            r = PI / 2;
        } else {
            r = - PI / 2;
        }
    } else {
        if ( py == oy ) {
            if ( px < ox ) {
                r = PI;
            } else {
                r = 0;
            }
        } else { // finally the general case
            if ( px < ox ) {
                r = atan( (float)( py - oy ) / ( px - ox ) ) + PI;
            } else {
                r = atan( (float)( py - oy ) / ( px - ox ) );
            }
        }
    }

    float hyp = sqrt( (float)( (px - ox) * (px - ox) ) + ( ( py - oy ) * ( py - oy ) ) );
    q.x = ( ox + cos(s+r) * hyp );
    q.y = ( oy + sin(s+r) * hyp );

    return q;
}

It's faster, but doesn't work correctly. I have 4 points denoted by the corners of a rectangle. I calc the center of the mass and pass it is as point 'o', then for each of the 4 points 'p' A calc their new positions. The resulting rectangle appears to rotate about the top-right corner ( which itself is traveling up and down a 45 degree line ). I can't for the life of me see where it is going wrong.

Waldermort22-Jan-07 1:40

Mutexes and sleeping threads

22-Jan-07 1:40

NM...

It was a stupid error in calculating the center of the mass.

lib file

mike dano21-Jan-07 21:42

mike dano

21-Jan-07 21:42

hi,

what is the need for advapi32.lib??

Re: lib file

Nibu babu thomas21-Jan-07 21:58

Nibu babu thomas

21-Jan-07 21:58

mike dano wrote:
what is the need for advapi32.lib??

For dynamically linking to advapi32.dll which contains registry related functions, service related operations and many more.

Just use dependency walker to find out what are the functions being exported by advapi32.dll

Nibu thomas
A Developer

Programming tips[^] My site[^]

softwaremonkey21-Jan-07 21:00

softwaremonkey

21-Jan-07 21:00

Hi,

I have some code that tries to get hold of a mutex using WaitForSingleObject and if it succeeds, it performs a sequence involving a delay using Sleep(). My question is, will the thread still own the mutex while it is sleeping or can other threads get hold of it? I DONT want other threads to be able to grab the mutex during the delay. The code is something like...

{
if(WaitForSingleObject(m_hDcpdMutex, DCPD_TIMEOUT) != WAIT_OBJECT_0)
{
return false;
}

m_pKeithley->ReadChannel(m_nCrackPDChan[i], &pOffVals[i]);
SetCurrent(1); // Turn current on
Sleep(m_nSettleTime); // Allow to settle
m_pKeithley->ReadChannel(m_nCrackPDChan[i], &pOnVals[i]);
SetCurrent(0); // Turn current off
ReleaseMutex(m_hDcpdMutex);
return true;
}
Any help/comments would be much appreciated!

Tony

Re: Mutexes and sleeping threads

Nibu babu thomas21-Jan-07 21:10

Nibu babu thomas

21-Jan-07 21:10

softwaremonkey wrote:
My question is, will the thread still own the mutex while it is sleeping or can other threads get hold of it? I DONT want other threads to be able to grab the mutex during the delay. The code is something like...

From the docs:

Only one thread can own a mutex at any given time. <code>The owning thread uses the 
ReleaseMutex function to release its ownership.</code>

Nibu thomas
A Developer

Programming tips[^] My site[^]

hash_map in VC6 [modified]

whatever@whatever.com21-Jan-07 20:22

whatever@whatever.com

21-Jan-07 20:22

Hi,
I am trying to use some open source codes which is trying to include the <hash_map> header and it's not found in VC6. May I know if it is possible for me to download the missing header and source somewhere and use it in my project?
I saw a website as below:
http://www.cs.cmu.edu/afs/cs.cmu.edu/user/gchen/www/download/stl/download.html[^]

How can I use it? Thanks.

-- modified at 4:27 Monday 22nd January, 2007

Re: in VC6

Cedric Moonen21-Jan-07 20:24

Cedric Moonen

21-Jan-07 20:24

whatever@whatever.com wrote:
which is trying to include the header

Which header ?? We can hardly help if you don't provide at least minimum information about your problem.

whatever@whatever.com wrote:
May I know if it is possible for me to download the missing header and source somewhere and use it in my project?

Probably not because if you don't have the header file, you probably don't have the necessary library neither.

Cédric Moonen
Software developer

Charting control [v1.1]

Re: in VC6

whatever@whatever.com21-Jan-07 20:47

whatever@whatever.com

21-Jan-07 20:47

Sorry. its using the hash_map> container. any idea if i can download the library and include it in my project? Thanks.

Re: in VC6

Christian Graus21-Jan-07 23:43

Christian Graus

21-Jan-07 23:43

hash_map is not part of the STL. Perhaps you can get it from boost, or something ?

Christian Graus - C++ MVP

'Why don't we jump on a fad that hasn't already been widely discredited ?' - Dilbert

How to convert doc files to pdf files?

asenthil_858521-Jan-07 20:00

asenthil_8585

21-Jan-07 20:00

Hai to all..

i'm now started working in the field fo VC++..

Can any plzz tell me how to convert doc files to pdf files...

is there any example codes availble for doing this process...

plzz help me...

senthil

Re: How to convert doc files to pdf files?

nutkase21-Jan-07 23:15