Function Call causes sprites to move twice as fast

Link to .capx file (required!):

dropbox.com/s/bz6t7dotl65jtgq/bug_OnParticleCreation.capx

Steps to reproduce:

Fly the ship around for approx 20-30 seconds and you will see that some missiles move faster than others

Trigger:

Events Sheet: EvadeMain

Group: Main - Collisions Section

When the particle explosion is created via a function some missiles end up moving faster than they should

When the particle explosion is created directly in the collision code the bug isn't present

Observed result:

Odd missiles move at double speed

Expected result:

All missiles should move at the same speed

Browsers affected:

Chrome: yes

Firefox: yes

Operating system & service pack:

Windows 7 Professional

Construct 2 version:

Release 139 (64-bit/Steam)

Notes:

Although this test uses lots of spawned enemies and missiles to ensure the bug shows up, it also appeared during level testing when I had only 10 or so enemies and perhaps 20-30 missiles.

The bug was also present in other tests when the missiles used the Bullet Behavior / Move Forward command / direct Sin,Cos calculations.

Using some quick calculations on other tests I found the bugged missiles moved at exactly double the speed they are set to.

Please forgive the slightly larger code, I have spent five days tracking down this bug, from dissecting my game to creating small tests. In the end I started building my game from ground up slowing adding pieces until finally the bug appeared again.

I will try and create a more compact test later next week

Cheers

Link to .cap file

Here is a more compact file...

dropbox.com/s/mq2a14cm54ewhmi/bug_OnParticleCreation_Compact.capx

While I was reducing the code down the bug went away when everything was on one event sheet. I thought that perhaps the bug was caused by calling the explosion function from another event sheet...

However it seems simply including an empty event sheet makes the bug appear

• > If I include the empty event sheet the bug appears

• > If I remove the include to the event sheet the bug disappears

This has left me very puzzled

Browser Effected:

Firefox: yes

Chrome: yes

Can you reproduce in r143?

Ashley

I'm using the latest r143 and can confirm the behavior.

If you just run his 2nd .capx and watch, you'll see some bullets move a lot quicker than the rest.

Delete the empty include - EventTest - and re-run. It appears that all bullets move at a constant speed now.

zenox98

Glad that you can confirm the behavior.

This being my first project in Construct 2 and still learning the setup and calling functions etc, I went through rewrote, shuffled events so many times to ensure it wasn't my code.

Naturally I only used one event sheet when I started bug testing, so I did feel I was starting to lose the plot when I couldn't reproduce the bug.

It could be calculation error from the missile_Update function when fps drops too low, which on my PC, is around 44 FPS for this, which considering what's going on seems far too low IMO.

Is there a reason why you haven't used the Bullet behavior? It may be less of an FPS hog than manually calculating updates for the missiles.

I put a boolean flag on the missile to see if it's trying to move twice in the same tick and sure enough it is:

<img src="https://dl.dropboxusercontent.com/u/8367729/construct/pics/foreachtwice1.PNG" border="0" />

Then I printed out the IID and UID of each missile in the 'for each missile' loop and got this:

<img src="https://dl.dropboxusercontent.com/u/8367729/construct/pics/foreachtwice.PNG" border="0" />

zenox98

Originally the missiles did use the Bullet behavior however the bug was still present. I changed the code to use Move Forward to ensure it wasn't related to the Bullet Behavior.

I didn't come across any problems with the fps, during the game there are only a maximum of 20-25 enemies and 40-50 missiles at peak times also each missile has a short 5 second life span, so nothing close to the test files I uploaded.

I've only been using Construct 2 for 4 weeks so still not 100% sure what to expect in regards to Construct 2 speed capabilities and which routines are quickest. Now that I am a little closer to understanding what is causing the errors I'll probably revert back to using the Bullet Behavior.

ramones

That is an interesting result as I felt there had to be a double call somewhere. As I mentioned above the bug was present when I had the missiles controlled by the Bullet Behavior which is still odd.

I guess there could have been a problem during the For Each missile loop as well, however I doubt I would have spotted it as it was only used to control the turning and lifetime.

Cheers all

I hoping that in the short term if I use a single event sheet for the game that will cure the problem.

I can't reproduce any issue in my dev copy of r144. All missiles appear to move at exactly the same speed. Perhaps it's a bug we've already fixed.

Closing for now - if you can still reproduce with r144 when it's out, re-submit it again. It would also be helpful as per the guidelines to make a minimal example, only including objects and events directly relating to the bug, and also demonstrating the bug immediately if possible.