wave simulation
lazarus / 70-OpenGL

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Farida Basri · 2015-06-18 02:02

hi guys, i am new member in here
i also just start to learn about lazarus.
i never learn about programming before

could you please, answer my question about wave simulation?

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osddeitf · 2015-06-18 02:39

There are 2 app type in lazarus: GUI or non GUI.
First you have to learn programming in lazarus with non GUI app.
Create a project by: Project --> New Project... --> Simple Program -->
OK.
You see the code in Source Editor like this:

program Project1;

begin
end.

'program' is the keyword that define your program name.
between 'begin' and 'end' is the code that run while your program are
running.
Add those code to the between 'begin' and 'end':

write('Hello');
readln;

then run by press F9 key and see your first app.
You can also see in: http://wiki.freepascal.org/Hello,_World

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BitBangerUSA · 2015-06-18 02:41

quite likely someone(s) here can answer.

but you should be more informative...

ocean waves?
sine waves / math functions?
human greetings?

if you know very little about programming - you probably should spent
a good amount of time reading about programming - not specifics about
*how* - before you start coding. if you don't have a good idea of how
something works, trying to do it will only lead to frustration.

you might also want to post about what, if any, technical training you
have - regardless of subject. *good* programming requires critical
thinking.

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Farida Basri · 2015-06-18 03:01

Hi osddeitf
Hi BitBangerUSA

thank you guys for your comment and suggestion. actually i already
start learn lazarus since first semester (now i am at second
semester), but still not expert in programming.

now, i try to make program about water wave simulation.
firsty, i read jakarta's map from SRTM, and after that make wave
simulation.
but, when i click wave direction from TRadioGroup, wave only come one
times, not repeatly.

do you have any suggestion about my problem?

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BitBangerUSA · 2015-06-18 03:06

'still not expert in programming'

nor am i - but that doesn't stop me from doing it...

can't see your attached PNG while typing this...

you can and should post all or the important part of you code here -
use the Insert Code (# symbol) - then people can likely see what is
causing you grief.

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jc99 · 2015-06-18 04:54

Hi Farida,

Looked at the picture, looks impressing.
To the problem:

Does the wave come every time you change the direction ?
Or does it come only once, you click on the direction and never again
?
I second BitBangerUSA, post some code, or if it's not too big the
compressed project.
A good start would be the code of the events regarding the direction.
Since that starts the wave once.

PS: you've found the right spot. (you know what i mean)

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Farida Basri · 2015-06-18 05:17

Hi jc99
Hi BitBangerUSA


jc99 for your question :
Does the wave come every time you change the direction ? No, the waves
only come one time and not likes the real water wave in ocean, hehehe

this is code for that wave

procedure TForm1.Button2Click(Sender: TObject);
var
  Hight : real;
  trackbaru : integer;
begin
    //---- Clear Initial Value ------
    Wnew := Nil;
    Wnow := Nil;
    Wold := Nil;
    SetLength(Wnew,MapW+1,MapH+1);
    SetLength(Wnow,MapW+1,MapH+1);
    SetLength(Wold,MapW+1,MapH+1);

    trackbaru := TrackBar2.Position;
    Hight := trackbaru/10;
    //----- Set Initial Value -------
    //for j :=0 to MapH do
    //for i := 0 to 0 do

    for j :=0 to 0 do
    for i := 0 to MapW do
    begin
      Wnew[i,j] := 0;
      Wnow[i,j] := 0;
      Wold[i,j] := 0;
    end;

    Case WaveDirection.ItemIndex of
     0:    // --------- Make Wave From West
       begin
         //----- Set Initial Value --------\\
         for j := 0 to MapH do
         for i := 0 to 0 do
           begin
             Wnow[i,j] :=Hight;
           end;
       end;

    1:    // --------- Make Wave From Nort West
       begin
     //----- Set Initial Value --------
         for j := 0 to 0 do
         for i := 0 to 5 do
           begin
             Wnow[i,j] :=Hight;
           end;
       end;

     2:   //----- Make Wave From North
        begin
     //----- Set Initial Value --------\\
          for j := 0 to 10 do
          for i := 0 to MapW do
            begin
              Wnow[i,j] :=Hight;
            end;
        end;

    3:  //----- Make Wave From North east
    begin
    //----- Set Initial Value --------
        for j := 0 to 0 do
        for i := MapW-10 to MapW-1 do
          begin
              Wnow[i,j] :=Hight;
          end;
    end;

    4:  //----- Make Wave From east
    begin
    //----- Set Initial Value --------\\
      for j := 0 to MapH-1 do
      for i := MapW-10 to MapW do
         begin
           Wnow[i,j] :=Hight;
         end;
    end;
    end;
end;

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osddeitf · 2015-06-18 08:41

First, the code:
Code: [Select]    Wnew := Nil;
    Wnow := Nil;
    Wold := Nil;
must be
Code: [Select]    setLength(Wnew, 0, 0);
    setLength(Wnow, 0, 0);
    setLength(Wold, 0, 0);
And make sure you use a Timer with an event of it to repeat the wave
like this:
Code: [Select]// create a timer with an interval such as 100 to create
a wave repeatly after 100ms
procedure TForm1.Timer1Timer(Sender: TObject);
begin
  //put your wave create procedure here
  //if you have a timer before like Timer2, add this:
  //Timer2.enabled:= true;
  //and put Timer2.enabled:= false; before the 'end' keyword of Timer2
Ontimer Event
end;
And create some code that reset the wave when click Button2 on its
event

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jc99 · 2015-06-18 17:45

Quote from: osddeitf on June 18, 2015, 10:41:57 amFirst, the code:
Code: [Select]    Wnew := Nil;
    Wnow := Nil;
    Wold := Nil;
must be
Code: [Select]    setLength(Wnew, 0, 0);
    setLength(Wnow, 0, 0);
    setLength(Wold, 0, 0);
Explanation: if you just set the values to nil, you most likely don't
free the formerly used memory.
Setlength makes sure to release the memory used by the array.
My suggesstion here is:
Initialize the field's in an OnCreate or other initialization-event.
And just Put all the Knots to your desired value.
  
Quote from: osddeitf on June 18, 2015, 10:41:57 amAnd make sure you
use a Timer with an event of it to repeat the wave like this:
Code: [Select]// create a timer with an interval such as 100 to create
a wave repeatly after 100ms
procedure TForm1.Timer1Timer(Sender: TObject);
begin
  //put your wave create procedure here
  //if you have a timer before like Timer2, add this:
  //Timer2.enabled:= true;
  //and put Timer2.enabled:= false; before the 'end' keyword of Timer2
Ontimer Event
end;
And create some code that reset the wave when click Button2 on its
event
Here I Disagree. if you have a simulation, than you already have a
timer / thread, or whatever you use compute the simulation.
With your on-Button-event you create a defined disturbance which runs
trough your simulation-field.
If you want a constant wave / or wavefront to run through your field,
you should set a knot of your choice to a function of your choice
(e.G: a sine, or triangular )
for a wavefront you have to set a bunch of adjected knots. This acts
as a Wave generator.
you could also play with an adjustable damping at the edges, to
simulate other reflections.
Think of the whole Sim as a waterbasing, and with the on Button you
hit the surface once. If you want an ongoing thing you have to
simulate that too.

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Farida Basri · 2015-06-19 13:01

Hi osddeitf
Hi jc99

Thank you guys for suggestion.
Sorry i just reply your comment now, i already try your suggestion
guys, but still got an error.
Could you tell me please if did something wrong?

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zbyna · 2015-06-19 13:30

If you want to help from somebody post also other files from your
project directory.
Here is information:
http://wiki.freepascal.org/Lazarus_Tutorial#The_Lazarus_files

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Farida Basri · 2015-06-19 14:39

Hi zbyna
Thank you already remind me 
i realized make mistake

https://www.dropbox.com/s/mxa59h836nfn02f/JakartaOk7_Edit.rar?dl=0

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jc99 · 2015-06-19 15:45

Hi,
First of all your loop-Variables should be local,
You can use the Command-Completion-Shortcut <Ctrl>-<Shift>-C to do it.
( referes to all
Code: [Select]FOR i := ...
FOR j := ...
Statements. )

Second
Assigning an absolute PAth in the Source-code is a very unpleasant
thing.
do something relative e.G:
Code: [Select]'..' + DirectorySepator +'Data' + DirectorySepator +
'oki.txt'
or ask the User what file to load.

Third:
Set the Timer to Enabled := false
and enable it at the end of Butten1Click.
Then set your Simulation time in the Timer-Event (FSimTime)
and set Hight to a function relating that time.
Code: [Select][...]
  FSimTime := Fsimtime + 0.1;

    trackbaru := TrackBar2.Position;
    Hight := trackbaru/10 * cos ( FSimtime);
[...]

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jc99 · 2015-06-19 16:41

try that ...
data is in ../data/WaveSim/..

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howardpc · 2015-06-19 18:01

Good work, jc and farida.

(Note, in Button1Click() you need to free bitmap and resizedbitmap to
avoid a memory leak).

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jc99 · 2015-06-20 05:03

@howardpc:
You are right, i wanted to point that out on my last post that there
is a mem-leak (i had not figured out where), but i was a little in a
hurry.
So:
Code: [Select]  [...]
  //Open pic
   bitmap := tbitmap.create;
   resizedbitmap := tbitmap.create;
   TRY  // <--
   bitmap.loadfromfile(FDataDir + DirectorySeparator+'WaveSim'+
DirectorySeparator+'Jakarta.bmp');
   newheight := Round(MapH/4);  //resize pic
   newwidth := Round(MapW/4);
[...]
   resizedbitmap.Canvas.StretchDraw(stretchrect, bitmap);
   Image1.picture.bitmap := resizedbitmap;


  ShowMessage(' MapW = '+FloatToStr(MapW)+ ' MapH = ' +
FloatToStr(MapH)+' DataMax = '
       + FloatToStr(DataMax) + ' DataMin = '+ FloatToStr(DataMin));
  FINALLY // <---
    freeandnil(bitmap); // <---
    freeandnil(resizedbitmap); // <---
  end;

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Farida Basri · 2015-06-21 02:50

Hi jc99
Thank you for your help 
but, can you answer my question about :

1) Why i used this code :
 assert( fileExists (FDataDir + DirectorySeparator+'WaveSim'+
DirectorySeparator+'oki.txt'), 'No Oki.txt - File');

 AssignFile(F,FDataDir + DirectorySeparator+'WaveSim'+
DirectorySeparator+'oki.txt');

because normally when i want to put directory for my map i used :
AssignFile(F,'D:\\Smad-Lock(Brankas_Smadav)\\#MATH
MODEL#\\JakartaOk7_Edit\\JakartaOk7\\JakartaOk\\oki.txt');


2) Could you explain, what you mean with directory separator? sorry,
but i am confused

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jc99 · 2015-06-21 03:40

Quote from: Farida Basri on June 21, 2015, 04:50:01 am1) Why i used
this code :
 assert( fileExists (FDataDir + DirectorySeparator+'WaveSim'+
DirectorySeparator+'oki.txt'), 'No Oki.txt - File');

 AssignFile(F,FDataDir + DirectorySeparator+'WaveSim'+
DirectorySeparator+'oki.txt');
 
because normally when i want to put directory for my map i used :
AssignFile(F,'D:\\Smad-Lock(Brankas_Smadav)\\#MATH
MODEL#\\JakartaOk7_Edit\\JakartaOk7\\JakartaOk\\oki.txt');
Assert makes sure the some axioms are set.
Here: that the file exists.

You used an absolute path.
This is fine as long you are the only on to run your App.
But no one else can run your app.
And not even you when you move it to another computer.
So you should set it to something relative to your Exe , or your Home-
Dir, or somthing more project related.

Quote from: Farida Basri on June 21, 2015, 04:50:01 am2) Could you
explain, what you mean with directory separator? sorry, but i am
confused 
DirectorySeparator is replacement for '\' on windows, and '/' on Linux
or whatever character an operating system is using to separate
directories in a path.

I have a strict separation between files.
Project, source, data and binary-files are each in separate folders.
(So i can switch between compilers, computers, os's ... )
Project: .\fpc, .\dxe, .\d7 ...
Source: .\source
Data: ..\data\<pro>
Bin: ..\bin\<target>
   Units: ..\bin\<target>\units
To get the thing running I had to move your data-files.
in your case I suggest you initialize FBaseDir to 'D:\\Smad-
Lock(Brankas_Smadav)\\#MATH MODEL#\\JakartaOk7_Edit' or whatever you
see as your basic Project-path.
and fill the rest in like  + DirectorySeparator+'JakartaOk7'+
DirectorySeparator+ 'JakartaOk'+ DirectorySeparator+

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Farida Basri · 2015-07-01 14:23

hi jc99
hi osddeitf
hi howardpc

hi friends, i really appreciate your help to me.
nice to know about all of you
thank you very much