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How to script a bounce using layer in point ?
I’ve found a few different scripts for the bounce but i’m trying to make basic presets based on the layer in point and out points using sliders to determine the travel pixels on the x,y,z points. Meaning I want to quickly put my preset on a layer, type the distance to travel to get to the [x,y,z] values of the layer. So if I punch in -300 on the y axis it should start up 300 pixels and travel the duration I plug into another slider. I’ve got this going with keyframes but was hoping to do it without using keyframes.
I found this code but i’m still a novice when it comes to coding so I’m not sure how to properly parse this or if this would even work, still a nifty script from https://motionscript.com/articles/bounce-and-overshoot.html:
elev = degreesToRadians(75); v = 1900; e = .7; f = .5; g = 5000; nMax = 9; tLaunch = 1; vy = v*Math.sin(elev); vx = v*Math.cos(elev); if (time >= tLaunch){ t = time - tLaunch; tCur = 0; segDur = 2*vy/g; tNext = segDur; d = 0; // x distance traveled nb = 0; // number of bounces while (tNext < t && nb <= nMax){ d += vx*segDur; vy *= e; vx *= f; segDur *= e; tCur = tNext; tNext += segDur; nb++ } if(nb <= nMax){ delta = t - tCur; x = d + delta*vx; y = delta*(vy - g*delta/2); }else{ x = d; y = 0; } value + [x,-y] }else value -
3 Replies
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hey, one easy thing to do that i use to use a lot of times, is to remap a simple kf animation to in and outpoint.
something like this:
valueAtTime(key(1).time+time-inPoint) else if(effect("Checkbox Control")("Checkbox") > 0){ valueAtTime(key(1).time+outPoint-time)} else valuehere a little demo to show what I actually mean 😛
https://docs.google.com/uc?export=&id=1pVEv77rk1DAcwINbuiHCuaNih_k6sBpl
Ofcourse the expression itself is kind of basic, but its easy to use for all kind of properties.
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I think thats what you are basically looking for:
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While I guess it’s possible, this particular expression probably wouldn’t be a good candidate for inputs controlling the total distance traveled. Based on those entries and given values for launch angle, elasticity, gravity, friction, and number of bounces, you could calculate the launch velocity required to give you that result, but it would be messy.
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