Aizatulin

Hi, ok it looks like you want to chain transformations. Have you tried to multiply the matrices? Quaternions can be another option if you have many operations ... . Check my example. It contains 3 rotations matrices which are applied on a geometry in a specific order. If you look into my example, you can see that the first matrix rotates the box around its diagonal line. If you apply the second rotation the box still rotates around its diagonal line, if you change the angle for the first rotation, but now in the transformed space. matrix_chain.hipnc

Hi, but "rot" is your axis. If you rotate around this axis, this axis should stay the same, if you apply this rotation on it or am I missing something?

Hi Masoud, have you read my answer on sidefx forum? You can edit the bend wrangle inside the bend node. Just muliply/add your attributes to the related variables. The attributes can be set for each points (check my example). bendZ.hipnc

Yes, you can use or modify it, if you want. Here is another file with some optimizations. There are probably alot of other ways to do this (even much faster). You can randomize the input, to get different types of copies. In the helix for example you can modify the radius along the ramp. If you want to use other components (like helix, path deformer etc...), this should work aswell. Double_helixA.hipnc

If you want to create a DNA strand, you can use two helices (with different offsets). You can transform these two curves to a guide path using a path deformer. After this you can create attributes for orientation / legth / positioning etc... . With these attributes you can copy/transform a geometry (a box for example) to each of these position. Here is a setup. Double_helix.hipnc

Hi, the foreach loops over all values in the i[]@pts array. Your attributes i@i and i@pt are integer attributes (not arrays), so each attribute value gets overwritten for each turn in the loop. At the end these attributes will have the value of the last run of the loop. If you use arrays for example, you will get all values from the loop. for_each_pts.hipnc

Your subset should have id = 1 and the other points id != 1 (-1 for example). As I've mentioned before, this is just an example. You can rename this attribute if you want, but make sure to do this in python node aswell. With this method the parameters depends only on the least square fit (so the focus does).

This is just an option/example (related to your first picutre). If you don't want to use all points you can filter by id. By default you can use all but usually a curve with degree 2 won't fit good (higher degree has better chance for better fit). If you know you have a specific subset of points you want to use , you can set the id for this subset to 1.

You can define which points are filtered out. You will get different results with different ids. You know how to calculate the focus? As hint: If your parabola is y = a*x^2 + b*x + c the derivative is y' = 2*a*x + b. What will happen, if the derivative is 0 (base) and 1 (reflection at this point is from vertical to horizontal (45°)).

The focus is determined by the parameters of the parabola

set i@id = 1 for all points (set_id_example - node) and move the end-points of curve 2 along the x-axis.

the fit is already good, so raising the degree will only have little effect.

The id is used to select the points, which are used for the fit. If you want to use all points just set i@id = 1 in a wrangle. You can use cubic or higher degrees aswell just change degree in python node to 3,4,... . Every x-value has y-value in points set, since the values are extracted from the curve @P = (P.x, P.y, P.z), where P.x ~ x, P.y ~ y and P.z = 0

I haven't tried multiple y, but it sounds, that the fits are indepentent from each other. So if y has k components, it will perform k different fits for the same x, where each fit represents a function 1D -> 1D. You can invert a function if there is no y-value with multiple x values. For examples a parabola y=x^2 for y=1 there are two x-values with y=1: x=1 and x=-1, so you can't invert this function.

Afaik this type of fitting only works for (1D) polynomial functions [like y = a*x^2 + b*x + c [which is degree 2] -> [a,b,c] will be calculated]. The "id" attribute is if you want to select a subset of points (not all points), so you can filter the "id" points. You cannot generally invert a function (or what do you mean with flip/invert?).