Make a mesh copy a roation with delay

Hi guys,

i would like to know if its possible to have a mesh copy the rotation of a bone with a delay. What i would like to achieve is a gas tank cap which opens with a small delay so the gap lock opens first and than the cap it self.

Ive attached a screengrab of this in action now. At the moment they rotate both at the same time. Im not really formiliar with rigging and armatures and dont really know what to search for on google

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Use two bones - one for the cap and one for the lock - animate them separately so the lock moves from say frames 10-20 and the cap moves from frames 20-40.

Cheers. Clock.

Update:

The tail of the bones should be at the hinge points, or you will have great difficulties animating it!

Rather than searching Google or a proper search engine for that matter, you could read the manual pages on animation or follow the Gus animation tutorial in the manual to get you started.

Well its not for animation at the moment. I use it to export certain settings while i keep the mesh rotations clean etc. I thought perhaps such a thing cold be done by scripting.

I do understand that i can animate it with a delay in frame numbers. But thanks for the help

Use an Action Constraint. You animate an action and hook it up to a bone. When you translate the bone, the action fires doing whatever you keyed in the action.

Thanks danpro, I actually found something like that didn’t get it working yet but watched a very old tutorial. Thanks for pointing me out I’m the good track!

+1 action constraint.
I’ve also never used it yet but I’ve seen some commercial use of it like a full deployement of an armor by moving only one bone :slight_smile:
Search on Cgcookie or whatever

I got it working like i wanted it. Some how one thing i dont get is when i move a bone, this bone has a limit rotation on x & z, in the transform panel it rotates on the z-axis? Also in the animation panel it shows the Z-axis, but in viewport it really is rotating on the y-axis??? Ive attached a screengrab, in the viewport you can see the axis of the Bone, but in the other panel it rotates on Z-axis.

Could some one explain this to me?

Ive attached the thing i needed, first small cap opens and due to the animation i setup separately i can call this??? if i understand it well.

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Small edit, made it go down first for the cap closer to move properly :slight_smile:

I got it working like i wanted it. Some how one thing i dont get is when i move a bone, this bone has a limit rotation on x & z, in the transform panel it rotates on the z-axis? Also in the animation panel it shows the Z-axis, but in viewport it really is rotating on the y-axis??? Ive attached a screengrab, in the viewport you can see the axis of the Bone, but in the other panel it rotates on Z-axis.

Could some one explain this to me?

Bones have their own axes of rotation, if you go to the armature pane and click the “Axes” checkbox you can see where the axes are. Unless you mess with things, a bones axes are generally; Y along the length, Z upwards, X normal to Z. You can of course change this by normalising the bones in Edit Mode and picking your own orientation system. You would keyframe a bones rotation by rotating in the 3D view - use the Global, Normal, Local, View, etc. axes modes, or by keying values into the bones specific rotation boxes and keyframing/driving that.

Cheers. Clock.

BTW - Shouldn’t the catch spring back once the petrol cap is open?

Aha nice tip! thakns for that. But i dont get what you meant by "Y along the length, Z upwards, X normal to Z. " cause Y seems like normal Z and Z seems like normal Y. Thats in edit mode, when i look in Object mode they look like ‘normal’ axis are layed out? Why are these 2 different if i may ask

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OK sorry, that’s the Engineer in me: To an Engineer, or Mechanical Designer, “Normal” means “At right angles to”.

So if you set view to front and make a bone that is vertical, the Y axis of the bone is upright or along the length of the bone from tail to head, following Global Z axis. the bone’s X axis is Global X and the bone’s Z axis is negative Global Y.

Now extrude the top of that bone to the right in the front view. The new bone’s Y axis is still from tail to head and now Global X axis, the new bone’s X axis is now negative Global Y and the new bone’s Z axis is Global Z.

If you normalise those two bones, select both and press CTRL-N > “Local X tangent”, both bones X axes will now align with Global Y, this is useful if you want to rotate the bones about the Global Y axis, you would then set rotations in the X Rotation Transform box for both bones and they will rotate about Global Y.

Confusing? Yes to start with but practice will help you. Just display the armatures axes to see which way round your bones are, in general (I say “in general” before some smarta*** corrects me), The bones Y axis runs from tail to head of the bone and the others obey the Left Hand Rule, where your thumb is Z and points up, your first finger is Y and points away from you and your second finger is X and points across your body from left to right. Just twist your wrist and you will see that all bones obey this rule. Hold your fingers as below for the Left Hand Rule:


Always align your hand so your first finger is pointing from tail to head of the bone and then twist you wrist so your thumb follows bone Z and the rest is easy, until you snap your wrist that is! This rule also applies to Global, Local, View, etc. ad infinitum, the axes in Blender and 3D programmes in general, or at least the ones worth using,

Hope this clarifies things a little.

Cheers. Clock.

Wow thanks for the information. For me that a bit to much for now but i do appreciate you taking all this time to explain it. Is it me or is it weird that bones have different anf confusing X, Y & Z axis than???

To be honest it is VERY useful, whether its weird or not (probably is weird - certainly confusing to the new rigger!), since you can rotate a bone precisely about any its OWN axes even when that axis is not in line with either the global, local, normal or view axis systems. But I agree - it takes some getting used to! It’s especially useful if you keyframe directly from Transform box inputs - more on this later I suspect.

Cheers. Clock.

okay it will make sense when or if i learn more about it. For now ill let it rest and leave on a top shelve of stuff to learn :wink: