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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16 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
27 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 ...
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1answer
21 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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22 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 ...
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1answer
160 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 ...
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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 ...
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1answer
44 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 ...
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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?
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1answer
60 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 ...
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1answer
31 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 ...
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2answers
358 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 ...
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1answer
28 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 '...
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1answer
22 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
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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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26 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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30 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 ...
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1answer
92 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 ...
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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
171 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 ...
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0answers
45 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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20 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
43 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 ...
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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 ...
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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
20 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 (...
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1answer
119 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 ...
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1answer
84 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
11 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 ...
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1answer
22 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. ...
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3answers
994 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 ...
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2answers
114 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 ...
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1answer
159 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 ...
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1answer
65 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 ...
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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 ...
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1answer
18 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?
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1answer
207 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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47 views

How to get driver's own full data path?

For example I set a driver to rotation_euler x of a bone called "Bone_L" and it uses a my custom function in driver_namespace. I need to get other half of Bone_L,Bone_R's animation data and ...
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1answer
131 views

No Compatible GPUs RTX 3080 Windows 10

I already tried to reinstall Windows using the keep files and apps method. Still no joy. Already tried switch between drivers (471.96) Could someone please help?
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0answers
63 views

Driver changing value of shape key based on a value of another shape key

I am a total newbie when it comes to writing drivers in Blender. I have two shape keys, one is to change the shape of an object and the other one is to fix clipping while changing shape with the first ...
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0answers
30 views

How to parent an object while still maintaining local coordinates?

I'm rigging some wheels, and the best method I've found to wheel rotation is to use the local coordinates of a controlling empty, whether with drivers, rigs or constraints. However, I need to turn the ...
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1answer
36 views

Trying to drive values with custom properties

I'm trying to drive the Lens property (focal length) of a camera with a custom property, to constrain it to a range (in this case, between 70 and 200mm). When this value goes from 70 to 200, I also ...
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0answers
13 views

.blend file suddenly won't open [duplicate]

I was working in the same .blend file yesterday and today. I switched over to a different project momentarily, then tried to switch back. Blender asked me if I wanted to save the current file before ...
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0answers
34 views

Shapekey driver miscalculates during playback and render?

video example, slightly NSFW I am using corrective shapekeys for my ankles (see video link above). The driver expression is the angle between two bone vectors. Blender does notify me that it's "...
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2answers
680 views

How to set up a driver to change value from zero to one every frame

I want to figure out how to set up up drivers that alternate from zero to one every frame. Id also love to know how to do it if i wanted to alternate every 4 frames or possibly value 1 for 4 frames ...
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1answer
149 views

Exposing geometry nodes attributes

Is it possible to output an attribute as a float/int/bool input value to another node? In my particular example I have a switch node and want the "is_exploding" attribute to drive the switch ...
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0answers
20 views

Bake a driven material property

I have a material where some of the parameters are controller via a custom property and a driver. I want to convert all those driven animations into actions. Is this possible?
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2answers
325 views

Driver expression for rotations with two limits

Object A is constrained to -20 degrees and +15 degrees rotation on the X axis. Object B is constrained to -90 degrees and +90 degrees rotation on the X axis. I would like the rotation of A to be ...

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