Questions tagged [drivers]

Blender drivers are a way to control values of properties by means of a function, or a mathematical expression. Use this tag for questions about Blender drivers.

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1answer
28 views

Scripted expression drivers: what is the syntax for an "OR" operator?

So I'm currently setting up some corrective shape keys on a character rig. I want a shape key to activate when a leg location is moved up (variable input A), OR, if the chest location is moved down (...
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0answers
6 views

Show custom properties in pose mode

I want to use a custom property on a bone as a driver. Can I get it to show up in the 'n' menu in pose mode, or is that just for object mode?
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1answer
32 views

Driver based on shading types/ change boolean when switching shading types

I have a Boolean property in my custom panel that I would like to either use a driver or can I use python to do make my option true/false Based on the shading type. I have searched up what I want, but ...
6
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2answers
455 views

Is it possible to write code in driver that would limit the output value between zero and one?

I wrote this expression. This is my ternary operator. But I don't know how to complete it using else if. if (location >= 1) else location I want to do this ...
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0answers
15 views

Set Objects appearance on using Drivers [closed]

My friend told me I should use drivers to easily change the attachments/parts of the weapon I am currently creating rather than going into individual collection and changing the appearance there. I ...
2
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1answer
50 views

light blinking randomization

I have bunch of lights. Id like to make them blink similar but slightly randomly In machine language: P - power - main parameter drawn in graph editor X - random value multiplier noise(time) or random(...
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0answers
39 views

How do I vary a driver's rate of change over time? [duplicate]

I have a driver on an empty's y-rotation. I want to be able to keyframe a custom property to change the rotation's rate of change. So I want the empty's rotation to speed up or slow down over time ...
2
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1answer
30 views

How change mesh form with an armature bone

I want to change the shape by moving the bone along the x axis. how to do it? meaning: when bone x = 0.000. it's a basic shape when bone x = 1.000. i want to change shape and save it to this state of ...
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2answers
26 views

How to script value in Shader so it changes over time?

I need this number to change in a given range over time. I thought that I could just write a driver to this value, but I did not find any random function that could solve my task.
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0answers
12 views

Why having X scale equal to 0 cancels driver influence?

Here's is the setup. Object A has rotation animation in XYZ Euler and contains child object B with additional animation also in ...
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0answers
26 views

Is is possible to have both drivers and keyframes on a single object? (3.0)

In After Effects it is possible to bind property of object 1 e.g. X rotation to same property X rotation of object 2 and still have control of self values with possibility of keyframing it. Example of ...
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1answer
18 views

Use a timeline marker in driver expression?

I see a very old question who's answer may have changed. I would like to use a marker (by name) in a driver function, as shown here: The 2013 answer is "no". Has this changed? I cannot ...
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2answers
38 views

How to add driver expression result from previous frame to current frames expression (way to compound expression output?)

I am new to blender and I cant seem to filter through all the resources to find an answer to my question. How can I create a driver expression that adds the result from last frame to the result of ...
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1answer
24 views

How to transform boolean object quicker

H i , i wanted to transform an object ( a cube ) which booleaned in different mode by another object ( an sphere) the way that it moves with out change , i found if i parent the second object to the ...
1
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1answer
28 views

Driver speed does not change #frame

I am driving an animated object on a curve through a follow path constraint via #frame in the offset. When I try to slow it down by typing #frame/10 or #frame/100 the speed does not change. What am I ...
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0answers
23 views

How to stop driver's "TRANSFORM_FINAL" Error message from popping up in system console

There is a bone called CTRL_Head and it has Copy Location constraint. I added a driver to this Copy Location constraint's mute state. This driver simply checks scene's custom property and if this ...
3
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1answer
162 views

problems with float variables

I'm trying to regulate an animation with a driver. However I got a problem with the equations. As reported in the picture I've a variable that is "0.9". I want to take the 9. My idea was to ...
0
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1answer
37 views

IK rotation control question

please see the picture below. there are 3 bones, bone A,bone B, and bone C.bone A is bone B's parent and bone A and bone B are connected. bone B has IK constraint and chain length is 2, target is bone ...
2
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1answer
49 views

Use a driver to programmatically set the positions of many vertices

I would like to use the position of an object ('driver object') as a parameter that interactively sets the positions of many vertices in a mesh. These positions are some nontrivial function of the ...
1
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1answer
25 views

How to find out what functions exist?

I`m currently creating some shape key and trying to apply them with a driver. I want to find out $tan()$ function is available. How can I know what function that available in driver or anywhere?
1
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1answer
80 views

How to fix "Can't edit driven number value, see graph editor for the driver setup"?

Was following a tutorial on objects, animations, geometry nodes etc. And within the Geometry Nodes section I have a value node in which I've used the function ...
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0answers
46 views

Create an operator to Use shape keys to view changes in an object's size

I am trying to create an addon which will demonstrate what an object will look like if the object changes width, length or height. I am thinking that a shape key would be the best way to accomplish ...
0
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1answer
33 views

Python constraints Influence control

There are two objects, Object A and Object B. Object A has Track To constraint and its target is Object B, then I would like to control this Track To constraints influence based on the distance ...
4
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2answers
361 views

Beginner issue with getting a Driver to refer to "self" so I can link it to many objects

I'm trying to get an object to scale with its distance to another object, so I can then link the driver to the rest of the 639 objects in the collection. I need it to somehow refer to itself, rather ...
0
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1answer
29 views

I need a Challenging 'Scripted Expression' problem solved

The general solution I am looking for is basically a Distance Input Variable. The reason why it doesn't work in my case, is because the value doesn't go past zero into the negative numbers like how a '...
1
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1answer
24 views

Bulk remove shape key drivers

How do I remove all shape key drivers from an object. Manually removing every driver would take much to long
2
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1answer
19 views

Driver and corrective shapes issue

say I have a bone that rotates between -45° and 45°. There is a way to make a driver that applies shape_A between -45° and 0°, and shape_B between 0° and 45° ? Or do I have to create two different ...
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0answers
27 views

Procedural/Value Depending Animation/Keyframe Start

I am wondering if there is a way to set the keyframes in shader editor or graph editor depending on attributes or values. For example you have a cube and when it turns red the keyframe animation ...
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0answers
32 views

How to transfer facial mocap from Blendartrack?

I’m loving the results I get from Blendartrack for facial mocap but the mesh is baked. I really need to get that motion to a full 3d character with the face of the person I scanned. I’ve been using ...
3
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1answer
93 views

Driver Editor not showing HSV instead shows RGB

I have this idea of being able to apply Complimentary color theory in scene to minimize the time (I know results might be differ when applied in post and when applied in the scene). So, my idea was ...
0
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1answer
24 views

How can I make this camera movement (with drivers)?

I've been trying to orbit objects with a motion similar to the attached video, but I cannot make it. I'd like a driver based solution since some trigonometry seems to be involved. https://imgur.com/a/...
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0answers
192 views

Accessing Geometry Nodes Attributes in Drivers

I have read the answers to this question, so see you can access Geometry Nodes-generated attributes on an evaluated object using Python. I'm attempting to access a mesh-wide vector-attribute in a ...
3
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0answers
47 views

Material Color from Rotation Angle

I basically have a two-part hinged lever. One arm is fixed, and the other arm can rotate in Y 0 to -45 degrees (X and Z are constrained to 0). So it's rigid body active -> hinge -> rigid body ...
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0answers
22 views

Drivers and Framerate Drops: Why?

Let's say I have 24 objects, each with their own material. The objects and materials are all the same, but there are an equal number of copies of the material because I need drivers that target ...
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1answer
44 views

Using Drives to affect Two Shape Keys with One Bone

I have an object with 2 different Shape Keys to make an edge rise and fall, depending on the rotation of one bone. (see the Image) One of the shape keys raises the edge, and the other shape key ...
2
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1answer
31 views

Get the length of scene in driver expression

Is it possible to get the length of the current scene in a driver? I'm trying to make properties loop, without having to edit the drivers if I change the first or last frame. I'm coming from an After ...
1
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0answers
46 views

Animating a wheel using a speed property only

I am trying to set up a wheel rig where the animator is provided with a single speed property only. The speed value should be keyed by the animator over time and the wheels should rotate accordingly. ...
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0answers
21 views

Position a sphere on a heightmap [duplicate]

In my scene I have a heightmap (that is, a plane with a displace modifier) and a sphere. I want the z coordinate of the sphere to automatically match that of the heightmap when I animate the sphere's (...
1
vote
1answer
129 views

Create and drive shape key in Python

I am trying to create an drive a shape key using Python. I used this answer to create a shape key: Creating shape keys using Python I have been able to use this answer to create a shape key in Python ...
1
vote
1answer
85 views

Use 2 color pickers to drive one value?

I'm currently driving the hair and body base color from a single property on the character below. However, I'd like the hair to be driven by another property as well. So that both properties (when ...
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0answers
12 views

EXCEPTION_ACCES_VIOLATION

I was trying to export a few thousand stimuli manipulated along some dimension in one go. This worked fine for batch sizes of 17 000, but when I increased the batch size, Blender crashed. When I try ...
2
votes
1answer
24 views

How do I snap my driver's keyframe to the reference point in the driver's graph editor?

I am just working on some corrective shape keys for my character. These shape keys will be triggered by drivers. E.g. when my shin rotates I want the corrective shape key for my knee to be triggered. ...
3
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3answers
1k views

Can a driver use the current frame number as input?

I'd like to render an object only at Frame 20. The common approach seems to be set 3 keyframes at Frame 19, 20, and 21. It's not too bad, but I really wonder if I can just use the current frame number ...
3
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2answers
115 views

How do I rig retracting cylinders so that I only need one control bone?

What I am trying to do is to move the three bones in the middle in and out, and I can do that right now, but one by one because it's an FK chain However I want the bone in red to be the controller and ...
3
votes
1answer
161 views

I want to control a traffic light. Is there a way that i can access any "common" field from anywhere to the shader editor? [closed]

I want to control a traffic light. As easy as possible. So i have 3 objects with emitters and i would control the strength of the lights by 3 variables/custom attributes: Red, Yellow, Green - which ...
0
votes
1answer
71 views

How can I add custom drivers to rigify?

I've just switched from Maya to Blender. I have a rig created with rigify, and I have added some circle meshes to drive shape keys around the face. How can I add these drivers to the rig, so that I ...
0
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1answer
17 views

Shape Key Drivers Messed Up

I saw this video: https://youtu.be/Nc6ewpdBzxo, and I am trying to replicate it. See Time (14:30) to see him put together the drivers. The Drive Equations are Tan(var/2) and Tan(var/2)-1. It uses a ...
1
vote
1answer
20 views

How do I view the full text of truncated Driven Property "Tips" (Warnings, etc)?

I can't read the Tip (nor of the Warning) in this Driven Property box, and I don't seem to be able to resize it. How can I view the full text of the Tip?
6
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1answer
231 views

About terms : Data Path, RNA Path and Property

First of all, I'm sorry. My question seems to be somewhat comprehensive. While setting up the driver and writing related rudimentary scripts, I confirmed that both RNA Path and Property were mentioned ...
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0answers
17 views

Help with local coordinates with parents, constraints, and drivers [duplicate]

I'm trying to make a wheel rotation system using drivers https://youtu.be/3mIrbZb-ZQQ I have tried to fix this with drivers, constraints, and parents, all of them do the same thing.

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