onEnterFrame, physics, tweens, blurry images.

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onEnterFrame, physics, tweens, blurry images.

(8 posts) (3 voices)

Started 2 years ago by devatar
Latest reply from Daniel

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devatar
Member

I stared playing around with Sparrow about a week ago. First off, great job! I have a few questions...

1) If you were moving a bunch of SPSprite Subclassed objects around the screen (using velocity/acceleration properties, not SPTween) would you have the Stage's onEnterFrame call a "move" function on each object, or would you give each Sprite its own onEnterFrame listener and callback? Pro's and Con's of each?

2) Do you have any plans of adding a simple physics engine?

3) Having two tweens running at the same time with the same animateProperty causes a bit of a tug of war. Possibly when adding a new tween, any running tweens with the same animateProperty and target object are removed?

4) Tweening rotation can be slightly confusing...

Say you tween an object's rotation from 0 to -15 deg.
Then you tween the object's rotation back to 0.

At first I expected the 2nd tween to look like the reverse of the first tween, but instead it took the "long" way around the circle to get back to zero.

I ended up going from 0 to -15 and then, from -15 to 360 and it produced the desired effect

5) I have an SPImage loading a 32x2 PNG file, and then being added to the stage. The image looks blurred on the device but crisp in the simulator. Thoughts?

Thanks!

Posted 2 years ago #
Daniel
Primary Feather

Hi!

1) First of all: either approach is correct, both would work. Personally, I think I would call a "move"-function on every object manually, though. That way, I keep control of the time-flow in the main game class. When I have to pause the objects (e.g. because some message box pops up), I just don't call the "move"-functions for a while.

To simplify this, you could have those objects implement the "SPAnimatable" protocol, which is very simple to do, and add them to a custom juggler. Now, you can call "advanceTime:" on that juggler if you want the enemies to move (or not, if they should not).

But, as I said, that's just one way to do it =)

2) A physics engine is definitely on our "wanna have!!!"-list But currently, it's not our top priority, as there are some more "basic" things we need to complete first.

3) That can be problematic, you are right. I suppose I will add a "removeTweensForObject:"-method to the juggler, which can be called in those cases.

4) Wow, that sounds like a bug! I will have a look at it! It should behave the way you described it.

5) Hm, that's weird! The only thing I can think of: are the x- and y-coordinates of the SPImage object whole numbers (relative to the stage)? Because if the image "sits" between the pixels (so to say), it will look a little blurred. (That would not explain why it looks sharp in the simulator, though).

I hope I could help you a little =)
Best regards,
Daniel

Posted 2 years ago #
devatar
Member

Hey Daniel!

Thanks for the quick response and help

1) I will try that approach out, thanks!

2) A pure obj-c physics engine would be awesome

3) Sounds like a good solution, I actually looked around for a similarly named function that might have already existed before asking this question.

4) Ya it definitely feels like a bug.

5) Definitely using whole numbers everywhere. I did some testing with different sized images.

32x1 = blurry
32x2 = blurry
32x3 = blurry
32x4 = blurry
32x5 = crisp
32x6 = crisp
32x7 = crisp
32x8 = crisp
32x16 = crisp
32x32 = crisp

Hope this helps!

Posted 2 years ago #
Daniel
Primary Feather

Thanks for the detailed information! I will see what I can find out about that!

Until then, I suggest you use a texture atlas -- for performance reasons, that will be the preferred approach, anyway.

Daniel

Posted 2 years ago #
devatar
Member

Do you know of any good tools to created a texture atlas on OSX?

Thanks!

Posted 2 years ago #
Daniel
Primary Feather

Unfortunately not -- you will have to create it manually for now
But as I wrote in another thread, Sparrow will get its own atlas generator soon.

Daniel

Posted 2 years ago #
CJ
Member

For texture atlas packing, check out the zwoptex tool (and you can borrow some source from the cocos2d project to read the plist format into sparrow with a little extra effort)

http://zwoptex.zwopple.com/

Posted 2 years ago #
Daniel
Primary Feather

Another tool that can be used to create a texture atlas is "Packer", and can be found here:
http://slick.cokeandcode.com/

Its file format is very similar to Sparrow's, so I created a small Ruby script that converts it to the Sparrow format. This tool is not yet included in the Sparrow download package, so you have to get the "cutting edge" version via SVN (the Download page explains how to do that). It's in the "sparrow/util" directory. A README file explains how to use it.

(As OS X contains Ruby out-of-the-box, you should be able to use the tool without installing anything.)

Posted 2 years ago #

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