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the value of data slightly differ between json and binary

choigawoon

Hi, I'm C/C++ Programmer and using Spine 2.1.27 now.

excuse of my english skill,

If you cannot understand, reply to me. I'll try to make it better sentence.

anyway, I make my own binary format loader, and it has a problem with animation.

When I checked the data of skeleton between the one of json and the other of binary, they has small gap.

for example, a x position of bone
json / 208.929993
binary / 208.939606

a duration of animation

json / 1.333300
binary / 1.333333

my render engine has a fixed frame rate, it's 30ms per 1frame.

I assumed the small gap makes my render buggy when using the binary.

( It works fine with json )

Do I get rid of the gap for fixing problem?

or Is There a thing i missing?

plz help

choigawoon

Nate

JSON uses rounded values. Bone positions are rounded to 2 decimals, mesh UVs and vertices to 5, etc. Binary does not round values.

You gave 208.929993 as an example for a JSON bone position, but this should not be possible because only 2 decimal places are used. Are you giving the world position of your posed skeleton? Compare values from the data files, not world positions.

It seems unlikely that you can see a difference between the JSON and binary precision. Can you post what the noticeable difference is?

choigawoon

when i opened the json by notepad, they are the same as what you said about. (Bone positions are rounded to 2 decimals, mesh UVs and vertices to 5, etc. Binary does not round values.)

but, Loading it on the process, Some Bone positions are like 208.929993, 277.730011, ...

and the below values are weird.

do i fix the binary by flooring?

[Json]
[index: 14]
[Name: BOOM_01]
[LEN: 0.000000]
[X: -108.470001]
[Y: -267.380005]
[Rot: 0.000000]
[ScaleX: 1.000000]
[ScaleY: 1.000000]

[Binary]
[index: 14]
[Name: BOOM_01]
[LEN: 0.000000]
[X: -108.472351]
[Y: -267.387543]
[Rot: 0.000000]
[ScaleX: 1.000000]
[ScaleY: 1.000000]

I've just submit with the log and my implement.

more info

I've just found that my animation looks stepped with a binary in my render process.

but, it looks interpolated with a json in my render process.

I followed up the skeletonbinary of libgdx and made my own skeletonbiary in my attachment, SkeletonBinary.cpp.

I think the gap doesn't make a difference about my rendering.

I get stuck now.

now i'm looking at what's going on a CurveTimeline between json and binary.

Nate

Float cannot accurately represent all values. Eg, the actual skeleton may have a bone with X 327.872375 and that is the value that shows up in the binary data. In JSON it is rounded to 2 decimals, so you get 327.87. However a float may not be able to store that exact value, so instead you get 327.869995. This is just how floats work and isn't a problem.

All your numbers are identical for the first 2 decimal places. This means for binary the remaining digits are increased accuracy. For JSON the remaining digits come from float inaccuracy. The largest inaccuracy you will see is 0.0099999, which is just less than 1/100th of a pixel (assuming you draw at pixel sizes). I doubt this will make a visual difference. It definitely should not make a difference for interpolation. It sounds more like you may be reading animation data incorrectly.

choigawoon

thanks.

so, the gap of values between json and binary doesn't affect the interpolation of a animation. that's right?

( i 'm not talking about the interpolation between animations )

I would like to check my implementation.

have a nice day!

Nate

Correct. It's a very small difference and shouldn't affect interpolation.