Animation Practice: Thrusting (Patreon)

One thing I like to do in the animation community is give feedback and help people out if they're stuck.  Occasionally when talking with someone I'll offer to look into a bug they're experiencing or offer more creative help.  A little while ago a fellow artist was having trouble animating thrusting motions so we tried to work through it in various ways.  Eventually I decided to take one of their practice animations and try to do some revisions to see if that helped.

Below I've compiled the write-up I sent to them, complete with pictures, so the writing is going to be from that perspective..  I thought some people here might find it informative.  However it's important to note that none of this is the way to animate, but rather it was tailored for this animator's particular issues.  Most of what I say below can be traced back to the 12 principles of animation.

"In the project file I left your original animation earlier in the timeline and duplicated it to make my edits over at frame 40.  I took about an hour to see what I could do with it.  As a rule I wanted to keep the bones (heh) of your animation in tact, so I kept the timing and tried to keep the beginning and ends as similar to yours as possible.  That being said, I did make some changes to make it work with the animation a little better, mainly with Harley.  I also added a lot of finishing touches onto it that you didn't have in your original loop, but it's a habit of mine to see a loop through to completion before I can really judge it.  It works well for me at least.

I would say the first major thing I did was rework Ivy's thrust.  I wanted to keep the timing the same, so my goal was to give it a little more weight and power.  As it stood, she was sort of thrusting like a piston, back and forth.  But in order to add a little more anticipation and motion into the thrust, I had her swing downwards, like so:"

"Not only does it telegraph the thrust better, but it utilizes the power of her legs more.  By squatting down slightly with each thrust, she gets to use the power of her legs to lift up and forward, delivering more force.  You can barely see it in the final product, but it makes a difference."

"This next part was a little more complicated, but using some spine and neck bones I tried to communicate even more force in the thrust.  Before she was sort of levering back and forth, but now she's almost pulling Harley in and springing forward.  The swoop in from the hips is still present, but a lot of the horizontal movement is diminished.  When she thrusts forward, she pops back up which helps to sell the force of the thrust and the effort she's exerting.  The neck bones could use some polishing but they contribute as well."

"One thing I can't stress enough is the shoulders.  People always forget about the shoulders.  They are extensions of the arms and vital tools for showing exertion.  I kept it subtle in this animation, but I had the shoulders dip down and pull back as if she was pulling Harley into her thrusts.  You can barely pick it up, but with every other part of this animation, it contributes an important piece.

Lastly with Ivy I'll point out that the elbow and knee targets can play important roles as well.  It wasn't much, but having the elbow move outwards as she's pulling in helps communicate that she's exerting force towards her with her hands.

With Harley I focused more on timing.  With the original loop she was a little robotic, like a piston.  My goal was to focus her reaction around the thrust a little more but keep the beginning and end in tact."

"Her movement is still back and forth, but the timing is a lot different.  Her reaction is fast, but simple.  It's up to the rest of her bones to help smooth out the loop and sell the impact over a longer time-span.  The spine, neck, shoulders, hands, feet, breasts, butt... anything that can move really.  I didn't have time for the pony tails but those would help too."

"Speaking of hands and feet, I put a little bit of sliding in there to sell the force of the impact.  I may have gone a bit too far with the feet, but the idea is that the thrust is so hard that her whole body moves forward and she loses her grip for a second.  You can see the tiny bit of movement in the motion paths."

"Harley has always struck me as somewhat bobble-headed.  She's really loose in her movements and you don't ever get the impression that there's much tension in her body.  So I wanted to really show that in this loop and use it to help show the force of the impact.  The impact sends her head forward and with all that energy it sort of arcs in the air by the time the next impact hits.  If this were my animation, I might actually adjust the timing of the whole loop to get more out of that single action.  But as it stands, it's subtle but readable."

"Lastly I just wanted to cover the ripple effect.  A lot of people have adopted this technique, which is good, but it feels like a lot of people milk it and take it too slow.  There are some edge cases, like with chubbier characters, but for the most part you want the ripple to follow the force of the impact as it travels through the body.  It's OK if it sometimes isn't very clear.  Also sometimes a ripple just isn't warranted.  A lot of people get excited to use this trick, but the force of the impact just doesn't justify a significant ripple.  Plus, hand animation and shape keys can help add to the effect too.  In this loop I didn't use any shape keys, but I animated the butt and I think it contributed to the effect.

I did a bunch of other stuff here and there, but you can look through all that in the .blend file.  I just wanted to explain my general thought process.  Another important note: I didn't just animate one character and then the other.  I bounced back and forth between the two.  One character's movements can help inform the other's, even if one character is clearly in control."

And that's about it.  If people are curious I could post the .blend file, but I'd have to ask permission first.