View Full Version : Gears, Bones & Expressions HELP!!

03-06-2010, 08:24 PM
I have attached a scene I am making for bicycle safety.

The wheels move around depending on the Z axis movement of the main
bike object. ( using a relativity expression )

The pedals also linked through a relativity expression turn accordingly.

A null is attached to each pedal object & is the goal object to the ankles.

The ankle bone in each leg is has inverse kinetics up to the pelvic joint.

This part all works fine as in my attached scene.

Now I wanted "Spine_Lower_Bone" to pitch up and down.
So I gave it an expression


Hoping to at least see the "Spine_Lower_Bone" wiggle back and forth ( even if like crazy and in the wrong position ) as I could adjust that.

But the Spine Bone just sits in one position.
Maybe I can't get expression data from the Thigh Bone as it has inverse kinetics?
Or maybe because the only user data is from the bike's Z axis.


03-06-2010, 08:43 PM
You'll likely need to first activate the "After IK" mode by pushing a button in the Relativity expression panel, and activate interactive mode by running the command Make_Rel_Interactive from LWs main menu to see the action.

Just tried it. All of the above required and the CHAN() function didn't work. Perhaps that function can't read IK values at all (neither can channel modifiers btw). Use the more direct approach of P()!

Poor guy! His banging his head into the handlebar as he goes along.

03-06-2010, 10:11 PM
I can't get the expression right.
Could you please post the working scene.

thanks in advance

03-06-2010, 10:41 PM
I just put "P(thigh_right_bone,t)+2.5" into the P slot for the spine bone, turned on "After IK" and activated relativity interactive mode. The state of the latter doesn't seem to be saved with the scene. You'll have to activate it manually.