Controlling Rotation Speed

[Dan Ebberts]

This is one way. It’s not simple, but it works:

https://www.motionscript.com/articles/speed-control.html#linear

Dan

[Bhavesh Jadav]

Thank you for your answer
but i already checked that & i am not getting my results.
I want to do it without keyframes & speed should be controlled by slider control

[Dan Ebberts]

You would use that technique to integrate/accumulate the value of your slider control.

Dan

[Bhavesh Jadav]

Thank you for answering Dan

Here’s the scenario.
I have adjustment layer which has slider control, which controls the
speed of the fan. There is another layer ‘Fan’. I want to control
rotation of fan layer by speed provided in slider control.
There is no keyframe in any layers. On motionscript, it calculates the area of the graph, but in my case there is no graph.so is there any modification i need to do in that code?
If there is way please tell me.

[Dan Ebberts]

So how are you controlling the value of the slider? You initially indicated that you wanted to animate the speed of the fan, which I assume implies that you’ll be animating the slider value, correct?

Dan

[Bhavesh Jadav]

slider value is constant.
for example i enter 200 in slider value, the fan will rotate about speed of 200 rps(but not necessary 200 rps, around that value) with slowly increase its speed, 200 rps for some time & slowly decrease the speed & then stop. I am not animating slider value.

[Dan Ebberts]

How does the expression know how long the ramps are and when they start? If you define the ramp start and finish times in the code, I guess it would look something like this:


spd = effect("Slider Control")("Slider");
t1 = 0; // on-ramp start
t2 = 1; // on-ramp finish
t3 = 5; // off-ramp start
t4 = 6; // off-ramp finish

if (time > t4){
accum = (t2 - t1)*spd/2 + (t3 - t2)*spd + (t4 - t3)*spd/2;
}else if (time > t3){
v = linear(time,t3,t4,spd,0);
accum = (t2 - t1)*spd/2 + (t3 - t2)*spd + (time - t3)*(v+spd)/2;
}else if (time > t2){
accum = (t2 - t1)*spd/2 + (time - t2)*spd;
}else if (time > t1){
v = linear(time,t1,t2,0,spd);
accum = (time - t1)*v/2;
}else{
accum = 0;
}

value + accum


Dan

[Bhavesh Jadav]

Thank you for answering Dan.

According to your code the speed will increase from 0 to 1 sec & from 1 to 5 sec it wil be constant , then from 5 to 6 second it will decrease & finally it will stop. Right?
1 second ramp i want. I forgot to mention that.

[Dan Ebberts]

That’s correct.

[Bhavesh Jadav]

Oh Great.
Thank you Dan.
I will let u know if it works.
Thank you.