Objects going past obstacles, why?

I have some bouncing ball objects in my app that are surrounded by backdrops set to obstacles. The actual moving objects are set to not fine detection while the backdrops are set to fine detection. The objects moving around (at about speed 20 or slower) are set to bounce with these obstacles. It works about 90% of the time, but when i move around the scrolling frame i can see that some of them always seem to be outside the area surrounded with the backdrops, they seem to "slip through" mostly when i am not near them. But I have also seen some of the objects being stuck in the middle of a backrop https://dl.dropbox.com/u/4047131/MyPublic/02.png

Why is this happening? I know that fast moving objects can miss the collision detection with thin objects, but these backrops are 32*32 and the moving objects are set to non fine collision detection (making them a square of 32*32) and moving at a speed that is never faster then "20" (very slow). I have tried to toggle the "inactive if to far from window" option but it happens when this is both at automatic and set to No. That is also something I wonder. If I have a very big frame area and these moving actives are set to never go inactive, will they still be able to register collisions with the backrops? In other words, are they collision working on the backdrops at all time? (because I don't see a toggle for them to be inactive if far from the window).

Check in the runtime property of the frame if "Handle background collisions..." is checked, if not, check it. :)

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Originally Posted by EE

Check in the runtime property of the frame if "Handle background collisions..." is checked, if not, check it. :)

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It is checked

Hmm, that's very strange. Could you upload an mfa so we can have a look?

Outcast - have you got Inactive when far from frame ticked? If so, untick it (as may be ignoring collisions outside of frame?)

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Originally Posted by AyreGuitar

Outcast - have you got Inactive when far from frame ticked? If so, untick it (as may be ignoring collisions outside of frame?)

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Are you talking about this? " I have tried to toggle the "inactive if to far from window" option but it happens when this is both at automatic and set to No."

Outcast - Yes, that's what I meant. Sorry it didn't help! Perhaps you should upload an example mfa file or send one to ClickTeam explaining the problem.

Ok, here is an example mfa of the problem, you can fly around with the player object and the "balls" (squares really) are bouncing around. I also inserted an event that makes the "balls" stop when they go outside the playing area surrounded by the backdrops so you can see them without them floating away to far. Just go around a bit and you will see that the "balls" are slipping through all over the place! :/

I actually just had this problem about half an hour and fixed it.

It was a combination of two maladies:
1. There were too many events going on. I had to condense a lot of them by grouping ones under the same condition together (it's my own fault for not already having done that) and just rewriting a few other sequences.
2. In the animated sprites of the objects that were moving through other ones, the bottom did not always have any pixels on it. They were sprites of people walking, and what was happening was that they took steps into the objects instead of up to them; their feet moved across the edges of the other object so they never had any reason to stop. I fixed this by adding a small, unnoticeable pixel at the bottom of every frame of every sprite.

So far, I haven't had any problems since.

Outcast - Loading your example file and it said that that effect file Lens.fx is missing. I ignored it, and ran it. I don't see any of the yellow blocks getting outside the play area, although they do stop after a while. So perhaps the Lens.fx effect is the problem? I've never worked with effect files (seems to be different from the Lens object extension which I have installed)

Outcast - After some further examination of your example, I think the problem might be this line (although haven't seen it happen):
2. Pick one of "Ball" + 1 chances out of 100 at random = Set direction to (any direction at random)

Even though you have this before your collision with backdrop (line 4), the collision (in red) will happen first, so a Ball could bounce, but then randomly be selected and have it's direction changed so that it ends up inside an obstacle. You might want to set a flag when a ball bounces and only select Balls with that flag clear when you set them to a random direction. then at the end of your conditions clear that flag for all Balls.

Another thought is it might be your Load On Call being ticked for Ball - if there are none on screen and memory is low, it might be unloaded and only reloaded when comes back on screen. Try unticking this option and setting Inactive if too far from window to No.

Hope that helps!

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Originally Posted by AyreGuitar

Outcast - Loading your example file and it said that that effect file Lens.fx is missing. I ignored it, and ran it. I don't see any of the yellow blocks getting outside the play area, although they do stop after a while. So perhaps the Lens.fx effect is the problem? I've never worked with effect files (seems to be different from the Lens object extension which I have installed)

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Lens.fx is unrelated, its missing because I took this stripped down example out from my original project. Here is a video of what is happening: https://dl.dropbox.com/u/4047131/MyP...-21_200544.wmv

I did ask about on the chat yesterday and it seemed the problem is the fact that I use backdrops for obstacles and they go inactive when far from the screen. I had no idea about this and it came like a chock really. I thought using obstacle backdrops was the "regular" way to do stuff like this. I got the suggestion to replace all the backdrops with actives, but that was not an option to me because I have over 1000 of them and to replace them all would be to much work. Another suggestion was to take a screenshot of my level with just the backdrops in it and make a big active of it to use as the collision. This actually seem to work very well.

Wait what? Who told you to replace all bg's with actives?
That's utterly inefficient and plain dumb. Use backdrops, that's what they're there for.
It's better to find the problem instead of using random workarounds.
I haven't looked at your file yet, but I'm gonna do that tonight.

I couldn't reproduce your bug, though I noticed that all "balls" are set to automatic on "inactivate if too far...", are they supposed to inactivate? Also, why are you using 12 layers? I don't know if that's fixed, but some time ago the use of many layers could really mess with your fps and stuff.

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Originally Posted by EE

Wait what? Who told you to replace all bg's with actives?
That's utterly inefficient and plain dumb. Use backdrops, that's what they're there for.
It's better to find the problem instead of using random workarounds.
I haven't looked at your file yet, but I'm gonna do that tonight.

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But the problem was apparently that backdrops go inactive when far from the frame. So even if you have your actives set to not go inactive they wont collide with an inactivated backdrop. I was as surprised as you because I also thought one of the main uses for backdrop set to obstacle was for platforms.

About many layers I also got told that my big frame size would make my game run like a snail, but so far when I test it in FLASH (my full app, not this small example) it runs in 60fps :)

I have never ever had this problem with backdrops, and I've made huuugh levels. I've only ever heard of similar problems when there are conflicting events or properties. You could try and set all bgs and balls to fine detection, just to try it out, I recall someone somewhere talking about collision issues when using both of them.