Scratch

wow. how did you figure all that out?

Paddle2See wrote:

When a Scratch project is running online, it is actually running in an application called the Java Player which interprets the Scratch project and makes it run.  The Java Player is a totally different application from the Scratch program (where you make the projects).  So, while it does a pretty good job of running Scratch projects, it has it's own set of "quirks".  Sometimes you have to make some small changes to your projects to make them run on the web. 

I'm going to start a thread here to show some of the most common problems you may run into when you try and run your project on the web.  Feel free to add on your own experiences!

Timing and Initialization
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Often, the reason that projects act differently on the web has to do with the timing of things.  You may have several scripts all starting on a given Broadcast event (for instance) that really need to act in a certain order.  They work fine in Scratch but, because some events happen a little faster or slower online, they don't work right online.  You can usually cure these kind of problems by adding short Wait blocks ahead of the events that should happen later.

Also, make sure that when the Green Flag is clicked, the project is initializing properly.  That means that all the variables are set to the right starting values, all the sprites are put in the right starting place and so on.  Any Forever loops that are checking for a certain variable value should have a short Wait ahead of them to make sure that the variable has time to get set to the right starting value before the Forever loop starts checking it.

Large Sprites
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Sprites can get much larger than the Stage in the Scratch Program.  But, in the Java Player, sprites can not be larger than the screen.  The only work-around I know of here is to break your very large sprites into smaller values.

Color Effect
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The Set Color effect works differently online...the color numbers are different.  You shouldn't use Set Color with the expectation that it is going to end up with the same colors you get in the Scratch Program.

Thats pretty helpful if you need some help like that. I like it! 

kgordon wrote:

Here are two things I have discovered about what happens to projects when uploaded: the online java player does not change a variable by a certain number if the variable already equals a non-number. Also it utterly doesn't recognize the arcsign and puts it's version of the error symbol in your variable if you try to use it. Hope that helps.

Yes, it does!  I knew about the problem with variables but I hadn't heard about the problem with Arcsine.  Thanks!

I think I heard the set volume to and the hide/show variable doesn't work online.

Yeah the volume doesn't work but I didn't know about the hide variable/show variable (thanks to bosox397 for correcting me). Also timing can be a bit off sometimes and sometimes big projects slow down online. If I think of anything else I will add it.

Last edited by kgordon (2009-04-11 07:54:39)

bosox397 wrote:

I think I heard the set volume to and the hide/show variable doesn't work online.

I hate when that happens, I say please download to get better quality in project notes and they ignore that. Then they say  something like this: "the sound is all jumbled up" or "what are you saying"

it really annoys me because then u have to make sprites to cover the variables and they have to be exactly lined up, espicially with words

I found a couple more.

Besides Color, some of the other graphic effects (e.g. Pixelate and Mosaic) don't look quite the same.

Rotated sprites may be positioned differently by one pixel. Normally you wouldn't notice, but in a Tetris type game for instance, it could be important.

If only we were in a world in which scratch projects react the same way online and offline!

when i get on some computers and i go to a project it shows a grey screen where the project should be.

Here's one that came up again recently...if you use the Pick Random block to choose a sound for the Play Sound block...it will stop the Java Player dead in it's tracks!

*** Update - This is reportedly fixed in version 34 ***

Last edited by Paddle2See (2009-07-29 05:39:00)

keroro645 wrote:

Paddle2See wrote:

Here's one that came up again recently...if you use the Pick Random block to choose a sound for the Play Sound block...it will stop the Java Player dead in it's tracks!

Wow, I think my projects had that error.

In a game I was doing earlier, I did that but later got rid of it. Good for me...
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Even if the internet dies, Scratch shall live on.