MMF 2 - Odd Drag and Drop Behavior

[droberson]

If you create a new application with a frame. Then add an object like a ball.

Condition: When cursor is over ball and left mouse button is held down
Action: Set x, y locaton of ball to x, y location of mouse.

Problem I found this that it does not work and spotty in the way ball would try and fail to follow the mouse pointer.

Solution was to set up a counter

CONDITION: IF MOUSE IS OVER BALL
ACTION: SET COUNTER TO 1

CONDITION: IF LEFT MOUSE BUTTON IS PRESSED AND COUNTER = 1
ACTION: SET X,Y OF BALL TO X,Y OF MOUSE.

Not sure why a counter is needed. Drag and drop worked fine with a counter however. Ball would follow mouse and drop fine. Seems like a bug. Maybe checking speed in engine between first case and second???

[Anders]

By default MMF2 only runs 50 frames per second but the mouse moves much faster + that the mouse doen't move "smoothly" when moving fast. If you move the mouse fast enough, the mouse makes a big jump in it's position and gets outside the object and then making the 'mouse overlaps object' false and stopping the object getting dragged.

A good way to drag objects that is pretty safe:


+ Mouse clicks on "Object"
---> Set flag 0 ON

+ [Object] If flag 0 is ON
---> Set position to the mouse

[:"red"]X[/] Repeat while mouse key is pressed
---> Set flag 0 OFF


If you want to prevent multiple overlapping objects from being dragged if they overlap when you click them, you can maybe insert a 'pick "object" at random' condition into the first event. If that doesn't work, you can replace the 'click' condition with a 'repeat while mouse key is pressed' condition and an 'only one action when event loops' condition.

[Bovril]

This is not a bug, and no matter how fast you make the FPS, you will not make this failsafe (since windows itself makes the mouse jump large distances if moved fast). The counter method you're using is really the only way to do this.

Don't be afraid to do things the hard way; it's what programming is all about <img src="/center/images/graemlins/wink.gif" alt="" />

[MrCyberpunk]

What about this?

______________________
When Mouse is Over Active
+ Repeat while Left Mouse Button is pressed
Active Flag 0 On
_______________________

X Repeat while Left Mouse Button is pressed
Active Flag 0 OFF
_______________________
Active Flag 0 is On
Activate Group "Drag Ball"
_______________________
Active Flag 0 is Off
Deactivate Group "Drag Ball"

_______________________
GROUP "Drag Ball"
Always
Set Position to XMouse YMouse


Thats how I do my Drag and Drop for Actives and it works 100%

[Anders]

Having groups for such a simple thing is a bit of an overkill IMHO.

I think the 3 event method I posted is the best. That way you can also do relative drag and drop if you store relative coordinates in alterable values. Much neater than forcing the drag to stick to the hotspot.

[droberson]

I just wonder if Clickteam could make this a property of an object so if it is turned on it would just work and no coding would be needed by us users.

Example: Object can drag and drop
Object cannot drag and drop

This has to such a common practice it should be a property.

Just like in Windows XP with the drag and dropping of files into folders. There is code in the OS that allows this to happen for certain objects. For example desktop icons can be toggled on or off on if movement is allowed.

Same idea here.

[Sphax]

Not a bug at all. Sometimes you must program something in MMF... It's one thing that you must program. <img src="/center/images/graemlins/wink.gif" alt="" />