Digital Workshop

Trying to create a simple matching game with two variables to keep score.

<total> holds the number of objects sorted
<correct> holds the number sorted correctly.

I'm using a Variable Changed Trigger on the page to tell when all the objects have been sorted. i.e when total=3 in this case.

I then want to display one of two messages based on the value of total and am using a nested if so that the logic looks sometihng like:



Only it doesn't work. it Always shows the "again" message.

It does work though if I attached the "If correct" action to a button instead of nesting it within the "If total" attached to variable changed.

Is my logic faulty somewhere? I have another publication using Variable Changed and nested Ifs in this way.

Problem publication attached.

Hi,

Thank you for your enquiry.

The problem is that Opus is processing the This Object Dropped triggers on the coloured shapes before it processes the Object Dropped triggers on the drop zones. The <total> variable is therefore being updated a fraction of a second before the <correct> variable, so when <total> reaches 3, the Variable Changed trigger checks the current value of <correct>, sees that it is still set to 2 (as the update has not yet taken place) and displays the 'Try Again?' message.

There are various solutions, including adding a small delay (0.01 seconds) to the start of the Variable Changed actions, but the most elegant workaround would be to remove the This Object Dropped from the coloured shapes and apply Object Dropped All Objects triggers to the drop zones to increase the <total> variable.

I have attached a modified version of the publication to demonstrate this.

Kind regards,

Ah Bingo! I thought I was going barking.

I must have just been lucky with the timing on on the other one.

Are these little 'gotcha's something that come with experience or is their any info out there as to which actions are processed first?

When updating multiple variables at the same time, it is a good idea to try and isolate the variable actions to as few objects as possible, so that you have a much better indication of which updates are taking place in which order.

For example, in your problem publication, dropping a shape name onto the correct shape caused the name object to increase the <total> variable and the drop zone to increase the <correct> variable. However, unless you implement delays, you have no way of knowing which action is processed first (it happens to be the action on the text object, but I could only tell you this based on the behaviour of the problem publication).

However, if both actions are assigned to the same object, you can be sure that the top-most action will be processed first, followed by the next action in the list and this should eliminate any possibility of Variable Changed triggers interrogating variables before they have correctly updated.

Hooray...it's my 100th post!


I hope this helps. Please do not hesitate to contact me if you have any further queries.

Kind regards,

Congratulations Robin on your 100th post.

I must say, all your posts are consistent and even!

Ah, but most of Robin's posts have been replies to posts from others, and not self-generated, so that's a bit of a cheat!!

I hasten to add that that is no reason for Robin to cease posting, however......

Chris

Cheers, Robin. A very useful 1000th post!