Time remap based on velocity/direction?

[Andrei Popa]

Order of poses inside the comp : neutral, up, down, left, right.
Each holds one frame only.
Precomp framerate must equal active composition framerate.


neutralSpeed = 50; //pixels pe second, you can modify this
vel = position.velocityAtTime(time);

if (Math.abs(vel[0]) < neutralSpeed && Math.abs(vel[1])< neutralSpeed){
pose = 0;
}else if (Math.abs(vel[0])>Math.abs(vel[1])){
pose = (vel[0]>0) ? 4 : 3;
}else{
pose = (vel[1]>0) ? 2 : 1;
}

framesToTime(pose)

Andrei
My Envato portfolio.

[Mike Douglas]

Wow – that’s perfect! Thanks so very much, Andrei – you’ve just saved me hours and hours of work. Very much appreciated!!

[Sam Smith]

Andrei,

Appreciate I’m dragging this one back from a while ago but I’m trying to do something similar and hitting a brick wall.

The problem is my object is moving on an isometric plane rather than straight up and down so there’s never a point where either axis is 0. Using the expression above it just jumps between two sprites (positive and negative)

I’ve gotten as far as splitting the two dimensions out using the vel[0] and vel[1] but after that, I’m stumped.

Any pointers in the right direction would be gratefully appreciated.

Thanks,

Sam

[Sam Smith]

Okay, Just in case anyone else is looking for this I think I’ve solved it using by adapting another piece of time-remap sprite code found on here by Charlie Laud.

No all I need to do is work out how to keep it in the state it was before if speed = 0.

directionNum = 0;
dX = transform.xPosition.valueAtTime(time) - transform.xPosition.valueAtTime(time - framesToTime(1));
dY = transform.yPosition.valueAtTime(time) - transform.yPosition.valueAtTime(time - framesToTime(1));

if (dX > 0 && dY > 0) {directionNum = 0;}
if (dX &lt; 0 && dY &lt; 0) {directionNum = 1;}
if (dX &lt; 0 && dY > 0) {directionNum = 2;}
if (dX > 0 && dY &lt; 0) {directionNum = 3;}

framesToTime(directionNum)

[Andrei Popa]

I dont understand why it jumped only in 2 sprites in your case. It is build for 5 cases. UP DOWN LEFT RIGHT NEUTRAL. On each frame, it shows the one that is bigger(if the object goes left with 45-something degrees difference to horizontal, it shows left. If it goes with 45+something it shows up )
My expression is very similar to your. I just used the .velocityAtTime() to get the direction instead of accessing valueAtTime(time-frame)
The 50 pixels per second is for the case in which the speed is very low, case in which it will show the neutral pose.

Now for the problem with your case. You must go back in time frame by frame until you find a value that is not zero(for the speed) and make the current value that value. This will create long render times if your object sits in place a lot.

Andrei
My Envato portfolio.

[Sam Smith]

Not sure either – when I mapped the vel output to a text string it seemed to be that I got one sprite for a positive number and another for the negative. It didn’t seem to know if it was a negative x or y.

I don’t need a neutral state as the natural pose would be based on what sprite has just been displayed.

I’m guessing that could be achieved with some kind of

“if vel=0, then find vel-1 speed and use that”

With the resting state, I think I’m just going to slow the vehicle sprite down so it appears to be stopped. The scene is zoomed out a fair way so it should be okay, and reduce the number of calculations as I have a lot of small car sprites going around the city.

Thanks again for your help.

Sam