@KarmaBot sup ?

@KarmaBot hi Karma

@KarmaBot say how do you like it on main site?

ok, I guess :)

I think she's lost in her own thoughts...

Seems so

one more breaking news and then get to work :)

@KarmaBot breakingnews

So Islam is the answer to DNS server? Whoa, Green, that was creative :D

Allah is indeed mighty

Afternoon

coffee

I forgot my afternoon coffee

and, hi, @MikeL. :)

@KarmaBot say something nice about Mike L

@KarmaBot thanks but that was not really nice

@PavelJanicek how's your temperature? We're holding at a steady 301.

@MikeL. I am on same stable 300.15 Kelvins

living under roof is always bad

Hullo everyone

Hi

@KarmaBot sup?

Hello @bilbo_pingouin, looks like it's been a quiet week. Been away for Orthdox Xtian Easter

you need a space

@KarmaBot sup ?

oh, ok

@SerbanTanasa last week you mean? yeah... been a busy one for me.

I almost want to ask how the responses are generated

on SE-WB i mean

which responses?

Karma's?

yeah

well it's not about WB... but know how they are :p

sup = hi+say+smile :)

@KarmaBot sup

well, that makes no sense

@KarmaBot say that was a bit insulting

I can't...

And dont want

Sup command stays :)

And also the best command ever

@KarmaBot breakingnews

No, I can certainly remove the "sup" command... but I can't remove its last output

everybody here who loves trigonometry, rotate your arms 180 degrees along any axis!

I keep on finding my own knowledge on the subject to be lacking, and it confounds me how little good information there is on the Internet about how to rotate a camera in 3 dimensions

I mean, sure, it's probably a really complex problem, but that should just mean there are more people who've tried to tackle it

@DaaaahWhoosh I literally teach a course on this. What do you need to know?

@MikeL. well, I'm trying to get a camera to move like the human head. So when you're looking up and then to the side, you're moving to the side relative to your up-looking angle

@DaaaahWhoosh That's easy enough. What's your problem?

@MikeL. I guess it's just getting the angles to translate. I think the X-axis (up-down one, maybe it's not X) is always the same, but the Y and Z are going to be relative to that

so I want to translate the relative angles to... absolute angles?

I don't think I have all the right words for this

@DaaaahWhoosh Well rotating also rotates your axes, so follow-up rotations are relative to those new axes.

@MikeL. yeah, that sounds about right

The solution to your problem is to pitch, then yaw.

Vertical axis may be Y or Z depending on what software you're using.

Well technically it could also be X, but no commonly used systems do that.

well the vertical axis is Y, but rotating on that would be turning side to side, right?

I meant up-down as in rotating up and down

so the axis is sideways

@DaaaahWhoosh yup, that's the yaw axis.

okay, pitch and yaw are much better terms than the ones I didn't have before

@DaaaahWhoosh That may be X or Z then, again depending on which way you're looking. Most commonly, you're looking along the negative Z axis

so X is your pitch axis, Y is yaw and Z is roll.

The trick is that rotation is non-commutative.

How are you entering it? Using matrices, Euler angles, Quaternions, or what?

@MikeL. I think I've tried a bit of all of them, with varying levels of success

@DaaaahWhoosh The easiest way to achieve this will be through matrices.

Build a separate yaw matrix and pitch matrix and see in which order you need to compose them to get the desired effect.

wait, what's in the matrices?

You can also try them out independently, so you're sure they're doing what you mean them to.

@DaaaahWhoosh Just plain, single-axis rotations.

okay, this is starting to make sense

They should individually look like this: en.wikipedia.org/wiki/Rotation_matrix#Basic_rotations

Orthonormal, with a unit column and row.

You're likely also using homogeneous coordinates, so the fourth row and column will both be [0 0 0 1]

(bzw. [0; 0; 0; 1])

I recall not understanding what the w meant, but that it was better left not worrying about

@DaaaahWhoosh Ignore it for now. Just be sure to check that it's always 1.

I'm getting flashbacks to the things I avoided in my senior project that made the end result not work

but I think this will make sense if I stare at it long enough

when using the rotation matrices, what is the initial vector supposed to represent?

oh, wait

I think I know that already

@DaaaahWhoosh What initial vector?

"The following three basic rotation matrices rotate vectors"

I wanted to know what those vectors were

but I think it is a stupid question

Well, they rotate any vector.

yeah, for a while there I think I forgot what vectors were

So, it's whatever vector you want to rotate.

sometimes, I don't have enough RAM for maths

anyway, I do think I have the right mindset now. I just need to draw a lot of pictures

I think my main problem is that I want to apply roll, but it's going to have to be a function of pitch and yaw

I just don't know yet what that function is

@DaaaahWhoosh How does roll factor into this all of a sudden?

@MikeL. well, like I said, I'm trying to make the camera like a human head. And when I look up and to the left, I see in Dutch angles

or at least I think I do, it's hard to tell

@DaaaahWhoosh So? All you need for that is pitch and yaw, in the right order.

I'm going to take your word for it, because I don't have the words to argue

I mean, it makes sense what you're saying, I guess I just haven't tried it and seen what the computer does

@DaaaahWhoosh That's the effect of rotating frames of reference. When you apply pitch, you also rotate your frame of reference, so that what is yaw in the new frame of reference is a YPR combination in the old one.

@MikeL. right, but I'm wondering if there's a good way to use that frame of reference change, rather than just modifying the global rotation values

I guess there probably is, I'm probably just not familiar enough with Unity to know which variables/methods to use

@DaaaahWhoosh Wait, you're using Unity?

You should have started out with that.

:I

That tells me that your vertical axis is Z and you're using left-handed coordinates.

Also that you can build rotations from Euler Angles, convert them to matrices, multiply them to comose them and then set them as a Transform component.

oh, well okay then

so the Transform components would then be used as those rotation matrices you were talking about before?

just apply them to the object to rotate it?

@DaaaahWhoosh Every object has a Transform component. By manipulating it, you can transform the object (the entire subtree of the object, in fact), so yes, you can rotate, scale, translate, skew, what have you.

okay, but what about using the object's frame of reference like you were talking about before? wouldn't this still be using the global axes?

I don't know if global is the right word to use, but what I mean is that if you rotate on the x axis, the y axis isn't going to change

@DaaaahWhoosh Yes it is, that's what rotation does.

The thing is, transform is not tied to any particular frame of reference. You can apply it in any FoR you choose.

(now I'm talking about a transform as a mathematical concept rather than a Unity component)

okay, so if you apply a transform in Unity, it'll use that object's own FoR? And that FoR will probably be different after successive transforms?

@DaaaahWhoosh It will use the inherited FoR from the parent

which is the object's local FoR

But you can create as many as you like, even if you don't store them.

Until you compose them, that is.

and composing is a mathematical or a Unity thing?

@DaaaahWhoosh a mathematical thing, that Unity also does.

It's as simple as multiplying a pair of matrices, really.

okay, sure. so unity object has a frame of reference, I apply a transform to it which multiplies the matrices, and changes the FoR.

do I still need to do two different transforms, one for pitch and one for yaw?

probably...?

@DaaaahWhoosh Yes, but you can condense them into a single one.

all right, well, it sounds too easy still, but I won't know until I try it out

@DaaaahWhoosh It is easy:)

@MikeL. I want to believe you, but I had the hardest time getting anything to work last night. I kept on finding the same broken, misleading, bad code, I'm somewhat convinced everyone is using it now

@DaaaahWhoosh If I have time later in the evening, I can try and write you up five-ish lines of code that will do this.

@MikeL. I think I'd rather write it myself, but if you want to go right ahead. Maybe leave something out so I can add it in and feel like I contributed something

@Jim2B I'm not entirely sure I understand the use of the mcguffinite tag in some cases, including my question.

I feel like it's a secondary detail that doesn't help the question; going to space is not the point at hand.

@DJMethaneMan Hm. Large bounty + astronomy question. I guess I know what I'll be doing the rest of the week. :-)

Well, you have a history of really good, in-depth mathy answers so I am looking forward to your answer! :)