Dear all, (Why are my collisions not working?)

[Cyberbeard]

Hi,

I'm a budding designer using MMF2 as my tool to prototype games for university coursework.


There's a issue with collision detection (or execution upon collision) in my latest game, and while I'm decent with MMF2, I sometimes fail to see the obvious issues right in front of me.

Problem:

Five balloons are slowly drifting upwards (placeholder event is simply adding Y to balloon's current Y), and whenever I near either of them with a player-controlled fan, they will get pushed in other directions before ascending again once the fan is removed.

As these balloons collide, they are meant to simply stop, or bounce off each other. I have tried a dozen ways of implementing this very simple event, but no matter what I do, they eventually stack up on top of each other once I've pushed them around for a bit with my player-controlled fan.

Why do think they aren't recognizing the collision, and executing the appropriate event?

Thanks!

[Grim_Jester]

Which movement type are your balloons set to? Static, bouncing or something else? I don't have MMF 2 handy at the moment, but my guess is that the other movement types, especially static, don't work well with the bounce action.

If you think an event is not being recognized, have a sound play for the event. If the sound plays, the collision is being recognized, but it is unable to do the remaining actions for some reason.

[Danny]

If you're using a static movement the action 'bounce' won't work at all. If you're using a static movement and you're coding a custom movement you'll have to detect and code the manual bounce yourself.

If this is the case, I think Vector movement might be the best in your case for more flexibility. If not, the bouncing ball movement should do it!

As Grim_Jester said, the best way to detect if the collision is working at runtime is to play a sound to test.

[RhysD]

Hi,

Problem:

Five balloons are slowly drifting upwards (placeholder event is simply adding Y to balloon's current Y), and whenever I near either of them with a player-controlled fan, they will get pushed in other directions before ascending again once the fan is removed.

If you always adding to the Y coordinate then the collision checks are going to be ignored. Try adding another part to your Y movement event that checks if a balloon is overlapping another balloon, and then negate that event (right click it and go to negate).

[Cyberbeard]

I've tried using both static and bounce movements.

The negated upon overlapping condition suggested by RhysD did not work unfortunately. It only stopped the balloons whenever the fan wasn't near, which isn't what I'm looking for I'm afraid.

The sound file did play upon collision between balloons, so I suppose it's detecting the collision but won't play out my bounce or stop commands.

Any other suggestions?

Thanks!

Edit:

Since the balloons aren't allowed to move anywhere but UP for as long as the fan isn't near, and only in the direction the fan pushes it when it is near, could the issue be caused by the fan movement simply winning over other movements, prohibiting them from starting?

[Francois]

The problem with the collision condition (I'm not talking about the Overlapping condition), is that if it is true in one loop, it will NOT be true in the next loop. As you say you are moving your balloons by hand (by changing their Y coordinate), the problem must come from that.

As Danny says, I suggest you test the Bouncing ball movement. Restrict to the minimal number of directions (8), and make sure the directions of the object is always either 4 (45° right), 8 (top) or 12 (45° left), like this :

* Collision between Balloon and Balloon
Balloon bounce
* Direction of Balloon=16
Set direction of Balloon to 12
* Direction of Balloon=20
Set direction of Balloon to 12
* Direction of Balloon=24
Set direction of Balloon to 8
* Direction of Balloon=28
Set direction of Balloon to 4
* Direction of Balloon=0
Set direction of Balloon to 4

Not tested, but worth a try.