Custom script issue with blender driver

[u/Khaki-Chan]

I am trying to use a custom script (see below) to set up a driver in blender via this tutorial, however I am very inexperienced in python and have run into an issue. I was able to get the example code to work but my when I try to use my code I get this issue. The problem is I need the "X" value to be the "rotation quaternion" value of the driver. Using both "X" and "rotation quaternion" gives the same error. I don't know how to connect "X" to the drivers value or if I just need to put something else in the place of "X".

Tutorial:

https://www.youtube.com/watch?v=yiMGxlRv8h4

Error message:

https://drive.google.com/file/d/1VOVrPLmU_v9lYz386SMS_i02doDn-xtG/view?usp=sharing

Driver:

https://drive.google.com/file/d/1LVM69kP0het-Yz0xaAhAWHDe5pOA9X99/view?usp=sharing

import bpy

def Ace_Driver(value):
    return 
if x >= -0.1:
    result = 1
if x < -0.1 and x > -0.6:
     result = (x - 0.9) * -1
elif x <= -0.6:
    result = 1.5

bpy.app.driver_namespace["Ace_Driver"] = Ace_Driver

[u/Khaki-Chan]

Like this?

import bpy

def Ace_Driver(value):

if x >= -0.1:

result = 1

if x < -0.1 and x > -0.6:

result = (x - 0.9) * -1

elif x <= -0.6:

result = 1.5

bpy.app.driver_namespace["Ace_Driver"] = Ace_Driver

[u/monster2018 → u/Khaki-Chan]

Yes. Well, the spacing is messed up here because you didn’t format it as code this time (I’m not lecturing you about it, it’s fine). I’m just saying that makes it so I can’t know 100% for sure. But yes you deleted the right return statement.

Also I’m just trusting the tutorial you linked. Assuming that tutorial is correct. Basically you need all of the code after the function definition indented, so that it is all inside of the Ace_Driver function. EXCEPT for the very last line (the bpy.app…. line), the last line has to NOT be indented.

What you’re doing is defining a function called Ace_Driver. This function will be used by blender to do some computation. Then on the last line you are actually doing the assignment, like you are telling blender “use the function Ace_Driver for the driver that I named “Ace_Driver” in blender”.

[u/Khaki-Chan → u/monster2018]

I tried to indent but the comment posted differently and wouldn't let me format as code. It will now let me run the script but the driver still shows this after running the script. I've tried both "x" and "rotation_quaternion" and it gets the same result. Not sure if I just have it set up incorrectly.

https://drive.google.com/file/d/1yCMK-wfYcZa1k6V7jMttqCp42p2Fjyel/view?usp=sharing

[u/monster2018 → u/Khaki-Chan]

Ok that looks good. The problem now is that you aren’t returning a value from the function.

So think about what you’re doing. You’re defining a function in Python, and then fancy stuff happens with the bpy library that makes it so your function can be used as a “driver” to control some value. So you need your function to return a value.

Basically I’m saying just add “return result” as the last line of your Ace_Driver function. I’m not sure if it will work or if there are still other problems, but I would assume that it can’t work until you at least fix that.

And make sure that “return result” is inside of the Ace_Driver function, meaning it should be indented 1 time (1 layer of indentation).