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Tools Dev - Using it Wrong but Right

Posted by achild, 06 December 2012 · 1,092 views

Hi!

So, a while back, a good friend tested Stickimator. He is the perfect first tester. Why? Well, my friend is an amazing artist, but his computer experience goes just far enough to shoot his friends online on Halo 1-zillion. He is, for all practical purposes, clueless when it comes to digital art. In fact, I have been working with him on it - which is scary because I am almost as clueless as he is!

So, we scanned a drawing into Gimp and attempted to color it, and import the textures into Stickimator. I'm showing him the ropes in this tool: attach a skin to this bone here; press your mouse button to rotate that bone there; press ctrl+mouse button to freely move that bone right there.

The thing about the ctrl+free-move, though, is that it affects the attached skin in 2 ways. It rotation AND scales the skin because the bone is doing the same thing (rotation + adjust bone length).

So, armed with a good hour of me talking and doing far too much (he should have been just trying it out I think), he eventually gives it a whirl.

Of course, he used it exactly like I did not expect, using the ctrl+move action for everything. I believe the idea of posing bones by rotation only must have been quite foreign to him... so he just free-moved it all. This is when I realized that IK was going to be very important, not as an extra feature for the future, but as a necessity for now. And here in lies an important key in tool design and usability.

If you're willing, watch a customer/client/user use your software for the first time, even if they do it the "wrong way". This is an incredibly useful way to improve your application. I'll grant you that sometimes we figure out the best way the first time, and they really should take the time to learn it (RTM anyone?), but this is a rarity. Usually, we are too close to the software to really see. Just as the end user is often not close enough to really see. It takes both points of view, as well as a healthy does of humility.

Anyway, check it out! I am glad this came about, because it was fun to implement Posted Image

Posted Image

[edit - content basically the same but it was revised for clarity - should not be typing these up at 5 am!!]




very nice, i'm about to start working on an IK system myself, and it's inspiring to see other people's works=-)
Take into account elasticity is an important concept in animation, so maybe the reason that using rotation only seemed "foreign" to him is because it most likely just looked outright wrong from that perspective. Rotation alone won't do.

Take into account elasticity is an important concept in animation, so maybe the reason that using rotation only seemed "foreign" to him is because it most likely just looked outright wrong from that perspective. Rotation alone won't do.

Keep in mind this is only in regards to animating bone poses.
I'm not sure it's unheard of to use only FK to animate bones, esp. in a 2d environment.

Ultimately IK is [usually] only bone rotation, but you're posing them from the opposite point of view (I want the bone to reach here, software figures out the angles), whereas FK you rotate them yourself, in order to reach a target or pose.

I can imagine it did feel weird using FK, esp. with no experience in animation on his part, so he didn't even really try. But I disagree that rotation alone won't do, esp. since there are other options to reach it (IK for example). If I was a 2d creature, I'm not sure my bones would do anything more than rotate.

Maybe I misunderstand what you are saying - were you just agreeing that it needs IK to feel right? Or was it something else? Posted Image
I was talking about the "squash and stretch" principle, actually, which in several cases can't be achieved through just rotation (scaling and/or translation are needed as well). Also yes, it happens in real life, given muscles can stretch and such, not to mention bouncy stuff and if you want to give things a cartoonish appearance.

Using FK or IK doesn't seem to have anything to do with it, though IK seems to be a good way to save time and only caring about the most important bones most of the time.
Ah, got ya. Very helpful indeed.

What you are talking about is certainly possible in the skinning system. While you would expect squash and stretch as a result of the movement of bones, in this context the bones would not be directly responsible for knowing how to do that.

In fact, in many cases, I imagine for realism you would need to use multiple frames for the skinning (at least the body of the horse in the wikipedia article) as I'm not sure even scale+transform would be enough. Frame-by-frame animation is planned but not implemented yet, though it will be a piece of cake to do. Thank you for your feedback!
If you're observing someone in this kind of usability test, it's also helpful to ask them before they begin to speak their thoughts out loud during the process. You can record them (with the subject's permission) to ask questions about later so you don't interrupt the test.

If you're observing someone in this kind of usability test, it's also helpful to ask them before they begin to speak their thoughts out loud during the process. You can record them (with the subject's permission) to ask questions about later so you don't interrupt the test.

Indeed. Good advice that I will use next time.

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