Animating the (curves) Mean Tilt property.

Coding Python Support
1

Hey everyone,

Just wondering if it’s possible to animate the curves “Mean Tilt” property with python.

I know it’s not keyframable but would it be possible to add X amount of degrees to all points in a curve per frame incrementally?

For example I have a rope bezier curve and I’d like to rotate it longitudely along the rope, I can do this by entering edit mode, selecting all curve points and Ctrl+T to rotate the mean tilt, but I really need to animate this.

Thanks a lot for any and all help.

Cheers.

2

You could write an operator and load it to the frame change handler. I’ve done that for custom, un-keyframe-able animations before.

3

I wrote some code that may help here. It involves creating your own property that calculates the mean twist. Then you could probably animate that.

4

Thanks a lot for the code snippet. If it’s not too much to ask would you be able to do a simple blend including the code?

I’ve added a custom property on my curve and I can kind of see what your code is doing, just not 100% on how to implement it.

5

Or would you be able to put the code into a script that includes import modules etc? Not entirely sure how to implement your code… Thanks

6

This script creates a panel(used the panel template so it called “Layout Demo”) that has a animatable control for the mean tilt. You’ll find it in Scene properties.


import bpy


def my_handler(scene):
    get_tilt()


def tilt_update(self, context):
    get_tilt()


def get_tilt():
    obj = bpy.context.active_object
    cur = obj.data
    points = cur.splines.active.bezier_points
    rot = cur.mean_tilt
    tilts = [p.tilt for p in points]
    tsum = sum(tilts)
    if tsum > 0:
        mean = tsum/len(points)
    else:
        mean=0
    new_tilt = [t + rot - mean for t in tilts]
    points.foreach_set('tilt', new_tilt)


class LayoutDemoPanel(bpy.types.Panel):
    """Creates a Panel in the scene context of the properties editor"""
    bl_label = "Layout Demo"
    bl_idname = "SCENE_PT_layout"
    bl_space_type = 'PROPERTIES'
    bl_region_type = 'WINDOW'
    bl_context = "scene"


    @classmethod
    def poll(cls, context):
        return context.active_object is not None and context.active_object.type == 'CURVE'


    def draw(self, context):
        layout = self.layout


        scene = context.scene
        cur = context.active_object.data
        
        row = layout.row()
        row.prop(cur, "mean_tilt")
        
def register():
    bpy.utils.register_class(LayoutDemoPanel)
    bpy.types.Curve.mean_tilt = bpy.props.FloatProperty(name='Mean Tilt', step=100.0, default=0, unit='ROTATION', update=tilt_update)
    bpy.app.handlers.frame_change_pre.append(my_handler)
    
def unregister():
    bpy.utils.unregister_class(LayoutDemoPanel)
    del bpy.types.Curve.mean_tilt
    bpy.app.handlers.frame_change_pre.remove(my_handler)
if __name__ == "__main__":
    register()
7

Thanks so much! One thing I’m noticing is the script only animates 1 curve in the scene, is this due to it using the scene layout panel? If I changed it to the transform panel or somewhere else would that work individually on each curve? Thanks again

8

Nah, that’s because my original code was made to operate on the active object. I’ll fix it, but tell me exactly what you want it to do.

9

Ah! I see.

So I have 6 curves that I need spiraling (mean tilt) all at the same rate, not 100% sure on the rate yet as I’ll need to do a few test render sequences. If it’s easy enough to hard code an array of curve object names, I can fill out the curve object names in the script?

Thanks, I really appreciate your help.

10 

import bpy


def my_handler(scene):
    get_tilt()


def get_tilt():
    scn = bpy.context.scene
    rot = scn.mytilt * scn.frame_current
    for obj in bpy.data.objects:
        if obj.type == 'CURVE':
            cur = obj.data
            points = cur.splines.active.bezier_points
            tilts = [p.tilt for p in points]
            tsum = sum(tilts)
            if tsum > 0:
                mean = tsum/len(points)
            else:
                mean=0
            new_tilt = [t + rot - mean for t in tilts]
            points.foreach_set('tilt', new_tilt)
            points[0].tilt = points[0].tilt #force curve to update :P


class LayoutDemoPanel(bpy.types.Panel):
    """Creates a Panel in the scene context of the properties editor"""
    bl_label = "Layout Demo"
    bl_idname = "SCENE_PT_layout"
    bl_space_type = 'PROPERTIES'
    bl_region_type = 'WINDOW'
    bl_context = "scene"


    @classmethod
    def poll(cls, context):
        return context.active_object is not None and context.active_object.type == 'CURVE'


    def draw(self, context):
        layout = self.layout


        scene = context.scene
        
        row = layout.row()
        row.prop(scene, "mytilt")
        
def register():
    bpy.utils.register_class(LayoutDemoPanel)
    bpy.types.Scene.mytilt = bpy.props.FloatProperty(name='Tilt', step=100.0, default=0, min=0, unit='ROTATION')
    bpy.app.handlers.frame_change_pre.append(my_handler)
    
def unregister():
    bpy.utils.unregister_class(LayoutDemoPanel)
    del bpy.types.Curve.mytilt
    bpy.app.handlers.frame_change_pre.remove(my_handler)
if __name__ == "__main__":
    register()

I changed the value in the panel to be used as a multiplier, i.e. tilt * currentFrame, so tilt=2 will change the mean tilt 2 degrees per frame. Things could get wonky if you use high numbers and/or long animations.

11

why all so complicated?
use shape keys!
https://www.blender.org/manual/animation/shape_keys/index.html
they work same as mesh shape keys, and animate also the tilt.

You can also deform a curve by another curve. I did a lot of animation with it, like dna creation e.t.c. complex stuff but easy if you know your way around.

12

Hell, I didn’t even know curves had shape keys. :stuck_out_tongue:

13

Thanks heaps for the update, I will definitely take a look at this! Cheers

14

Thanks for pointing that out! Can shape keys have linear extrapolation? i.e run forever? I’ll look into this also. Cheers!