Euler Angles vs. Angles

[fredsmith]

First thing, is it true that:
1. _AX() is buggy
2. _AX(), _AY(), and _AZ() are deprecated, and therefore we should avoid using them

If those are true, it follows that we should be using Euler angles instead (like the English Documentation tells us to), right?

Therefore, we either need function(s) that can convert between those two, or a tutorial explaining Euler angles. (I myself have no idea about Euler angles, even after reading the Wiki article)

[JHaskly]

2. I don't really think that "deprecated" matters. It's not like they are going to be phased out in a later version

1. I'm not sure about this, as I don't use _AX

I'm not actually sure that there is a difference. If there is, Bwansy should be able to explain it

However, _EX is also not quite suitable as it is. If the model is facing south, it inverts (I think it's south...). But this can easily be rectified.

[fredsmith]

LOL Okay then... I'll wait for Bwansy to reply. XD

EDIT: Okay, looking at Chris220's Lua library, we find that he fixed _EX() by doing this:

Code:

function ex(chipNum)
   if(-math.pi<=_EY(chipNum) and _EY(chipNum)<=-math.pi/2) or (math.pi/2<=_EY(chipNum) and _EY(chipNum)<=math.pi) then
      local ex = -_EX(chipNum)
      return ex
   else
      local ex = _EX(chipNum)
      return ex
   end
end

In his library documentation, this is what it says...

Format:
ex(chipNum);

Description:
Outputs the euler X radian. Fixed bug of _EX() being reversed when model is rotated 180 degrees.

Example:
local EulerX = ex(CORE);

[JHaskly]

I wouldn't have done that. Too much code

Code:

-_EX(chip)*math.sgn(_ZZ(chip))

[bwansy]

According to the Japanese documentations, _EX/Y/Z() are the same as _AX/Y/Z(), but "optimised and works faster", but both are buggy. I can't tell for now exactly how _AX() is buggy, because like Juz, I've seldom used _AX/Y/Z(). And Juz is right about how to fix _EX().

[fredsmith]

Okay, thank you.

EDIT: Wait, so it's

Code:

function ex(chip)
    return -_EX(chip)*math.sgn(_ZZ(chip))
end


?

[bwansy]

Yes.

[fredsmith]

Thanks.

[Chris220]

I wouldn't have done that. Too much code

Code:

-_EX(chip)*math.sgn(_ZZ(chip))

Yeah, that's what I used in my update Lua library (never released because I didn't think anyone would use it)

The fix posted above was something I set up years ago, I think bwansy may have helped out with it

The best thing to use for a lot of cases, especially with 3D physical applications, is quaternion angles. They're a bit confusing to learn about at first, but relatively simple if you understand them. The reason they're so useful is that, due to their nature, they avoid the issue of the gimbal lock.

[fredsmith]

LOL well... I'm still taking my time learning physics... most of the stuff here is already beyond what I'm learning at school: I'm in Physics 12. I haven't even graduated from high school yet.

[Chris220]

It's always nice to teach yourself extra stuff outside of school, means when you get round to studying it it's really easy!

Take vector dot products for example. I've been using the dot product for ages now, for various things in my programming. I've only JUST started learning about it at college (I'm 18)
I dunno why they left it so late - it's really easy xD

[fredsmith]

Yes, I agree haha, it's awesome to learn extra stuff when you have the time. It's also great to apply something you just learned in school to RC and other physics games.

[DanielLC]

Personally, I prefer quaternions.

I remember testing AX()... and them not being the same. I could be wrong though.

[RA2lover]

i don't think that relates to the topic at all.

BTW i play algodoo too!

[freek4ever]

I play algodoo too same username