walking lines :)
lazarus / 39-Graphics

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speter · 2024-03-21 03:50

Here is another (hopefully) interesting graphics program!

It may not be a Koala or a fractal; but the graphics "move".

The program has 2 sets of lines that bounce around the form - and is
find of hypnotic.
It uses the Paint event, so should work on Mac's as well as Windows &
Linux.

I think I based it on an Amiga program I saw in the 1980s.

cheers
S.

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tetrastes · 2024-03-21 13:25

I'm sorry to write this, but your program is buggy.
Did you debug it?
For example, closing window without pressing "Stop" button causes
Access Violation (see attached picture).
Changing number of lines "on the go" causes different errors, such as
Access to invalid memory, Invalid pointer operation, Floating point
error ... Program hangs, and even if you close its window, it remains
in background processes, and you have to use Task Manager to remove it
from memory.

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LV · 2024-03-21 13:36

That's cool. It's not buggy. Laz 2.2.6 and FPC 3.2.2 Win11
P.S. As @tetrastes correctly noted, if you do not close the window
without pressing the "Stop" button and do not change the number of
lines "on the go".

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Thaddy · 2024-03-21 14:20

which means it is buggy by design...should never happen.

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tetrastes · 2024-03-21 14:22

It's cool, yes, but it's buggy.

But I have to say that I forgot to add Range checking   , so the
origin of all troubles is Range check error.

How to reproduce.
1.Major. Compile with Range check (-Cr). Run, press "Go" button,
increase the "Num Lines". Get Range check error(s). Without Range
checking it causes different troubles mentioned above.

2.Minor. Compile with Range check and Debugger info, run in Lazarus
with debugger, press "Go", close program with mouse not pressing
"Stop" button. Though may be this is debugger issue, as this doesn't
happen without debugger.

Lazarus 3.2 fpc 3.2.2 Windows 10

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LV · 2024-03-21 14:43

I really liked this graphics program. @tetrastes. I agree the author
has a lot to think about.

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speter · 2024-03-21 22:49

Thanks for the feedback everyone.

Clearly, I did not intend for the number of lines to be changed while
running.
I'll clean that up and post a new version in a couple of hours.

cheers
S.

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lainz · 2024-03-22 02:23

Great demo.

It looks like an old windows Screensaver from windows 9x.

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speter · 2024-03-22 03:13

Here is a new version.

The user can start/stop the lines by:
  + clicking on the button;
  + clicking on the (panel) drawing area; or
  + hitting a key.

Changing the number of lines now stops the lines.
Closing the program's window no longer gives an error.
If anyone spots any other issues, please post.

cheers
S.

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speter · 2024-03-23 03:31

G'Day Folks,

I was inspired (became more insane?  ) today and wrote a new version.

As you might see from the app capture below, if allows many "trails"
of lines.

If you find the program is a big slow, you could comment out the
"delay" code (but I'd suggest leaving the
"application.processmessages" line).

cheers
S.