C / C++ / MFC

4-Jun-01 3:49

Use Miscellany/Adverise section for that. This forum is not a place for promoting commercial programs.

Tomasz Sowinski -- http://www.shooltz.com.pl

.h problems

4-Jun-01 1:28

ihave an h - file with all my struct definitions. unfortunatly i need to include it in several other header files because these structs are used as arguments in the functions. now i always get an error because the compiler claims the structs to be defined more then one time.

is there any way to avoid this by defining a max recursion depth or similar ? thanks Dead | X|

Tomasz Sowinski4-Jun-01 1:40

4-Jun-01 1:40

You should use preprocessor symbols to avoid multiple inclusions.

#ifndef __FOO_H
#define __FOO_H

struct Foo
{
// whatever
};

#endif

Note that each .h file should have its own symbol - for foo.h use __FOO_H, and for bar.h __BAR_H.

Tomasz Sowinski -- http://www.shooltz.com.pl

thanx

4-Jun-01 3:46

yessss it works - finally thanx you saved my day (hehe, i always wanted to what these #ifndef stuff is good for at all)

Christian Graus4-Jun-01 3:04

Christian Graus

4-Jun-01 3:04

Thomasz's suggestion is correct, but I thought I'd mention another - if you use precompiled headers, it can be a good idea to include a file like this ( full of structs you will be using, etc ) in your stdafx file.

Christian

#include "std_disclaimer.h"

People who love sausage and respect the law should never watch either one being made.

The things that come to those who wait are usually the things left by those who got there first.

Jean-François Roberge20-Jun-01 5:01

20-Jun-01 5:01

Hi,

In your file.h, you should put a condition that if the header file has already been " include " in another file, the compiler will not had it another time. Use the #if !defined and #define instructions. Se the example:

//File : StringTool.h
#if !defined(_STRINGTOOL_) //Normally the name of your file with _ in front and at the end.
#define _STRINGTOOL_

//Between the #define and #endif, put your .h file

#endif // _STRINGTOOL_

Jean-François Roberge

Jean-François Roberge20-Jun-01 5:04

20-Jun-01 5:04

Jean-François Roberge20-Jun-01 5:05

20-Jun-01 5:05

Jean-François Roberge20-Jun-01 5:06

20-Jun-01 5:06

Jean-François Roberge20-Jun-01 5:08

20-Jun-01 5:08

OpenGL

v_krishnan4-Jun-01 0:08

v_krishnan

4-Jun-01 0:08

Hi,

I am developing an OpenGL application using MFC. I have a requirement that I need to redraw the whole scene every 100 millisecs. when I do this using windows timers and invalidating the client area each time, the CPU usage is 100%. The result is that the app cannot process any other messages like, keyboard, mouse etc. Can anyone help me in making this efficient.

Thanks,
Krishnan

Tomasz Sowinski4-Jun-01 1:11

4-Jun-01 1:11

Does your scene change every 100 msecs?

Tomasz Sowinski -- http://www.shooltz.com.pl

v_krishnan4-Jun-01 21:45

v_krishnan

4-Jun-01 21:45

Well, not whole of the scene, but some disjoint parts of the scene change. Currently, I redraw the whole picture. Is there any way to restrict drawing of only those parts which change and leaving the unchanged part intact?

Thanks,
Krishnan

Tomasz Sowinski5-Jun-01 0:49

5-Jun-01 0:49

> Is there any way to restrict drawing of only those parts
> which change and leaving the unchanged part intact?

Honestly, I don't know. But I think you need to move your rendering code to separate thread to make app UI responsive. I'd render to a bitmap and then blt results to the screen. Of course, you'll have to use some synchronization stuff (critical sections).

Tomasz Sowinski -- http://www.shooltz.com.pl

v_krishnan5-Jun-01 22:33

v_krishnan

5-Jun-01 22:33

I have done some performance tests on my app. They show that the time to actually issue OpenGL commands is more than the time to swap the buffers. as far as multithreading is concerned, I don't think that the CPU load would decrease by that.

Tomasz Sowinski5-Jun-01 22:54

5-Jun-01 22:54

: as far as multithreading is concerned, I don't think that
: the CPU load would decrease by that.

Multithreading is not going to reduce CPU load. Moving the rendering code to second thread will make your application *more responsive* - users will be able to more easily select options from the menu, resize the window or exit the program.

Tomasz Sowinski -- http://www.shooltz.com.pl

Masoud Samimi4-Jun-01 1:42

Masoud Samimi

4-Jun-01 1:42

Hi,

Having the advantage of using MFC, you could do any of the followings:

1/ The best is to create a separate thread to do that particular job for you while the application is idle.

2/ The other option is to have the message pump method.

3/ Last but not least, is to put your anmation code in the OnIdle method of the application class. Override the OnIdle and try your code lines there.

Hope these helped.

Cheers! Smile | :)

Pete Bassett5-Jun-01 23:23

Pete Bassett

5-Jun-01 23:23

Heres a mulit threaded OpenGL View class for you to use. It handles all of the threading issues for you. You just put your drawing code in the correct overloaded method and away you go...

http://mkennedy.101main.com/software/OpenGLandCPP.asp

Pete