C / C++ / MFC

Re: Problem with multiple bouncing balls program in C

19-Jan-18 0:36

Member 13632263 wrote:
my program doesn’t run properly

You need to provide more exact details than that, as we have no idea what you are seeing when you run it. It has to be said that these libraries are a throwback from the old days of MS-DOS and may not work correctly under Windows. See How to use graphics.h in visual C++ 2012?[^].

Member 1363226319-Jan-18 0:59

Re: Problem with multiple bouncing balls program in C

19-Jan-18 0:59

When I run it it just shows the Windows error that the program stopped working, so I have to close it.

Richard MacCutchan19-Jan-18 1:05

Re: Problem with multiple bouncing balls program in C

19-Jan-18 1:05

I am afraid that information tells us nothing. You need to run your code in the debugger which will help you to find out exactly where it is stopping. But, as I already said, this library is very old and may not work under Windows.

Member 1363226319-Jan-18 1:22

Re: Problem with multiple bouncing balls program in C

19-Jan-18 1:22

I have seen similar projects which ran very good. Here is what it shows after the debugging:

https://mega.nz/#!NRwEAJKR!KI5cTeFhAaagIaRlbBoba1ugKt1j2RYEgUkF4lc8Atc

Richard MacCutchan19-Jan-18 1:23

Re: Problem with multiple bouncing balls program in C

19-Jan-18 1:23

And what does that tell you?

Member 1363226319-Jan-18 1:54

Re: Problem with multiple bouncing balls program in C

19-Jan-18 1:54

To tell the truth, I don't understand.

Richard MacCutchan19-Jan-18 2:51

Re: Problem with multiple bouncing balls program in C

19-Jan-18 2:51

Then maybe you should forget this program and start learning C and how it operates in better detail. You cannot become a developer by copying other people's code and guesswork.

Jochen Arndt19-Jan-18 1:07

Re: Problem with multiple bouncing balls program in C

19-Jan-18 1:07

You might get out of bound array accesses when step is always >= 0.63:

total=n*7;
num=(int *) malloc(total*sizeof(int));
// ...
do
{
    j=0;
    for(i=0; i<=n; i++)
    {
        if (step >= 0.03)
        {
            // Possible out of bound accesses here (j >= total)
            // ...
            j=j+7;
        }
    }
}
while (!kbhit());

You have to change the for loop to

for(i=0; i<n; i++)

I also don't understand why you are only updating when step is large enough. If that does not happen, balls at the end of the array will be updated less often than the initial ones.

You are checking if the new ball position is outside and inverts the direction if so but are still drawing the ball when outside. A better solution might be drawing it at the border (here for x):

if (num[j]+num[j+4]>=getmaxx() || num[j]-num[j+4]<=0)
{
    num[j+5] *= -1;
    if (num[j]+num[j+4] > getmaxx())
        num[j] = getmaxx() - num[j+4];
    if (num[j]-num[j+4] < 0)
        num[j] = num[j+4];
}

Finally it might not work as expected because you have up to 7 balls and did not handle overlapping ones. I guess you want to detect also ball collisions which would result in no overlapping. But that is also not handled by your code.

Member 1363226319-Jan-18 1:53

Re: Problem with multiple bouncing balls program in C

19-Jan-18 1:53

Well, it didn't work and yes I also want to handle overlapping balls and make them bounce together and change direction. But, I don't know how. However, I don't have up to 7 balls. I actually use 3, but each of them has 7 data (color, position, speed etc.). That's why I use i at the for loop to count the number of loops (each ball). Then I use j to go to the desired data of each ball. All the data is being inserted to the program from a .txt file as you can see. It might seem stupid that I don't understand some thing. However, I am a beginner and I am trying to learn. So, please help me and be patient. I really appreciate your help.

Jochen Arndt19-Jan-18 2:21

Re: Problem with multiple bouncing balls program in C

19-Jan-18 2:21

Sorry, I missed the number of balls.

But my other notes are still valid (out of bound array access and why not updating with small steps). For timing purposes (slower movement), wait outside the for loop.

I suggest to start with one ball to implement and check the border bouncing. To be realistic, the new directions should be calculated according to the collision angle.

Then proceed with two balls to make it simpler. For collison detection you need another loop (runing from currently processed ball index + 1 to number of balls) to check for collisions like with the borders. Upon a collision you have to set the collision position as new position for both balls and adjust the directions (which requires a flag / state that the other ball has been already processed within the current loop execution). Again, the new directions should be calculated according to the collision angles.

To check the code, you can suppress the drawing and print out the positions and changings instead. Or write them to a text file so that you can inspect it later. For testing it might be also helpful to stop after each step and continue after a key press. So you can check your calculations.

Member 1363226319-Jan-18 2:30

Re: Problem with multiple bouncing balls program in C

19-Jan-18 2:30

I have already made it with one ball and I tried to continue with two, three etc. However, I still do something wrong with more than one balls and I can't understand what. I have been working on this for almost a month and I have tried everything. I also searched the internet and asked at other forums too, but still nothing. I only managed to make it with one ball. I understand what you say and that's what I am thinking too, but I can't put it inside code and make it run correctly.

Jochen Arndt19-Jan-18 2:56

Re: Problem with multiple bouncing balls program in C

19-Jan-18 2:56

Your posted code does not check for ball to ball collisions. You have to implement it. There should be examples in the net for the algorithms.

Victor Nijegorodov19-Jan-18 21:21

Victor Nijegorodov

19-Jan-18 21:21

Are you trying to recreate a 30-years old xonix game? Big Grin | :-D

Re: Problem with multiple bouncing balls program in C

Rick York24-Jan-18 7:17

Rick York

24-Jan-18 7:17

For your next assignment, extend your program to work in three dimensions and use OpenGL to display the balls. For bonus credit, display the bounding cube with translucent walls. In other words, partially transparent but not totally.

Good luck. Cool | :cool:

convert feet and inches to centimeters

nithiin_sai18-Jan-18 14:42

nithiin_sai

18-Jan-18 14:42

2 errors is coming can anyone help me

Jim Meadors18-Jan-18 15:49

Jim Meadors

18-Jan-18 15:49

Here are some possibilities: LMGTFY[^]

<sig notetoself="think of a better signature">
<first>Jim</first> <last>Meadors</last>
</sig>

Victor Nijegorodov18-Jan-18 20:38

Victor Nijegorodov

18-Jan-18 20:38

nithiin_sai wrote:
2 errors is coming can anyone help me

Maybe...
But only if you'll show your code and exact error messages. Cool | :cool:

CPallini18-Jan-18 21:47

CPallini

18-Jan-18 21:47

It could be worse, it could be raining.

Start app without taskbar icon

David Crow19-Jan-18 3:16

David Crow

19-Jan-18 3:16

nithiin_sai wrote:
...can anyone help me

At this point, no.

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles

_Flaviu17-Jan-18 1:56

_Flaviu

17-Jan-18 1:56

I saw here:
Creating an application with no taskbar icon[^]
an good solution to start an app without taskbar icon (which work fine), but how can I switch it back (I mean show taskbar icon at some point) ?

Richard MacCutchan17-Jan-18 2:11

17-Jan-18 2:11

You should post the question in the forum at the end of the article, so the person who created the code can answer.

Jochen Arndt17-Jan-18 2:20

17-Jan-18 2:20

If you use another method to remove the taskbar icon by the ITaskbarList interface (Windows)[^] as described in the article How To Hide A Window in TaskBar[^], you can add the icon later with the ITaskbarList::AddTab method (Windows)[^].

_Flaviu18-Jan-18 1:09

_Flaviu

18-Jan-18 1:09

Thank you ! This could be a good track to follow ... until then, I am facing to far more easy problem:
How To Hide A Window in TaskBar[^]
Smile | :)

modified 18-Jan-18 7:31am.

leon de boer18-Jan-18 1:40

leon de boer

18-Jan-18 1:40

The rules for that are spelled out in detail from Microsoft
The Taskbar[^]

C++

SetWindowLong(yourHWND, GWL_EXSTYLE, GetWindowLong(yourHWND, GWL_EXSTYLE) & ~(WS_EX_APPWINDOW | WS_EX_TOOLWINDOW));

Straight after you create the window grab the handle and change the style flags and it will stop it being displayed.

In vino veritas

Jochen Arndt18-Jan-18 2:07