Generate Curve from Motion Path of a Bone (to animate steering of a fork lift)

Question

The bone in between the front wheels is following a Bezier curve (black) and the whole mesh of the forklift (all in one object) follows. I need the motion paths of the wheels (more precice of the wheel bones) as a curve!

Reason:

I want to make the wheel bones follow that curve and point in the direction of movement (for correct steering) and further make them rotate along this curve with a driver. I want to unparent the wheel bones from the root and move them independently on their paths but in sync with the rest of the moving mesh.

Stuff thats not working:

I already tried to make the rear wheels steer by IK constraints and a driver bone which reads information of the bezier curve in front of the forklift but that does not do the job for me, since the radii of the Bezier curves I want the bone between the front wheels to follow are to narrow/ cover a too large range of radii.
I just can not bing this script to run. Perhaps somebody can explain how I do this step by step?
Btracer addon - I could'nt figure out how to follow the path of a bone which is parentet to another bone which is following another path (wheel bone)
The Motion Trails Addon isn't maintained anymore - not working on 2.8

Please help, I'm crying. The data is there in front of my eyes but blender does not allow me to use it

Text

Related https://blender.stackexchange.com/questions/133012/line-of-bones-to-travel-and-conform-to-curve-like-train-on-a-track-snake — batFINGER, Mar 12 '20 at 02:12

score 0 · Answer 1 · answered Mar 11 '20 at 21:56

0

My good Buddy ClockMender has an excellent tutorial on this. \

answered Mar 11 '20 at 21:56

AJCDFIN

139
5

The problem getting the motion path into a curve still exists though. – M.Hoppe Mar 12 '20 at 09:06
The motion path is just visual, thats it. – AJCDFIN Mar 12 '20 at 15:13

score 0 · Answer 2 · answered Mar 02 '21 at 13:22

#select the armature

lastbone = 3 #index of the last bone (3 bones then is 2)
import bpy
ob = bpy.context.object
mp = ob.pose.bones[lastbone].motion_path
if mp:
    path = bpy.data.curves.new('path','CURVE')
    curve = bpy.data.objects.new('Curve',path)
    print(curve)
    bpy.context.collection.objects.link(curve)
    path.dimensions = '3D'
    spline = path.splines.new('BEZIER')
    spline.bezier_points.add(len(mp.points)-1)
for i,o in enumerate(spline.bezier_points):
    o.co = mp.points[i].co
    o.handle_right_type = 'AUTO'
    o.handle_left_type = 'AUTO'

Hello, thanks for your answer. Could you elaborate a bit on what exactly the script does ? Maybe add a few comments for people to understand it better. Thanks :) — Gorgious, Mar 02 '21 at 14:34

Generate Curve from Motion Path of a Bone (to animate steering of a fork lift)

2 Answers2