Esther Trilsch

You can use the AttribAjustArray SOP, it comes with a viewer state. if you set the Attribute Class to Points it should show your joint tags.

It seems to be just the dropdown not showing the current dict attribute name. So for now you would just need to type in the name. We will see that this is fixed.
The actual functionality is there though. Bind an input in your script e.g: . If the input name aka myInput matches the name of a key entry of the correct type in your dictionary, then that value will be used when you run the script. you get the result of the script running on the first output of your apex script node.

I used various triangular math function to create the setup. Both for the lower and the upper moving gearing elements.

Its a bit hard to describe but I hope the text below helps to get a better idea of the process.

The lower gearing compares the difference in length of the adjectant side of a triangle from the lower gearing joint to the connecting point on the wheel and to the point parallel to the start point. We know that our elementat can not change lengths so we always know how long the hypothenus of that triangle needs to be. We also always know here the end point of our gear will be since we have a control there that sits exactly at that position. if i know calculate a triangle with exactly the same hypothenus lenght and the given height deduced from our point going through that new upper position i can automatically calculate the length of the adjectant and add that to the current position of my lower gearing.

Our lower gearing is not properly moves the piston pointing up to our upper gearing since we have an aim there.

That already gives us a lot of info to calculate new positions to based on triangles again. Based on the root position of piston pointing upward and the position of the middle pivot we can first calculate the angle that the piston is currently at. We also now the rest positions of out upper gearing elements. We calculate now the vertical distance of our middle pivot point to the upper gearing, with thoses positions. The angle and the hight allow us to calculate the distance the upper gearing would move if it would be 'glued' to the upper gearing.

Next we take the direction of the movement into account. We can calculate the direction based on the cosine of your weel rotation.

The offset behavior which represents the collision behavior is set up based on and if-else setup. We use the min and max positions that our upper gearing could be and that if-else setup together with the direction. So if your piston moves in the forward direction and is moving beyond a given max value we need to move our upper gearing along, otherwise it doesnt move for example. You can also calculate those min and max position automatically based on triangular math if you want to be fully procedural and adaptive to your pivots. For time reasions i simply positioned them by hand.


So all the math described here is based on pivots and rest pivots and one rotation value from our main control. This gives us the advantage, that you can very nicely change the proportions of elements in your model and the rig can adapt to those new proportions.