Cineversity

Hello
I’m trying to do the following : I have a plane that I “criss-cross” with splines.  Imagine a wall with a bunch of hooks, and there are “ropes” connected to these hooks.
My “wall” is represented by a plane, and my ropes are represented by splines.  What I’m trying to do is texture the areas on the wall that are “inside” a set of splines.  I’ve attached an illustration as it is probably not clear…The red shape would be one of the “fills” between splines.

I’m not sure how to approach this, how can I select or create geometry between specific splines?  I tried using an extrude, but it’s method of producing geometry is too messy.

Thanks!

C4d file
https://www.dropbox.com/s/up8bbogpmtms6ma/SplineShapeSelect.c4d?dl=0

Illustration
https://www.dropbox.com/s/4i1y3vq6jlhkkxo/2020-06-22_17h42_39.png?dl=0

Hi Alex,

This is undoubtedly more a task for a specialized plugin. I’m not aware that it exists. It needs to calculate the crossing points among the Spline and set then the four points for a quad polygon on those four points. That sounds perhaps simple, but when I look into the Mathematics book for CG, it tells me that there are three outcomes for each crossing point. There is one; there is none, or there is an infinite number of such (line matches the other line [Spline]). Then to the next crossing…
Then it needs to be established which four points are designated for one polygon. Even one Spline moves from below to above or crosses another (X).

So, in a nutshell, I have no idea how to do exactly that with Xpresso, or in a way that I can communicate it here.

What I suggest is the following:
https://www.amazon.com/clouddrive/share/CQyNZBySCEtTva57HT9FdAxU2iE5OtyvNd33t1T4ZlF

I have set up two Objects, and each has several long polygons. The long edges are selected and got a Cylinder (not a spline…)
With the Explode, I separated the Polygons (virtually), and that gave me the option to colorize those. While transparent, the second set up (similar) mixes the colors, and each crossing field contains a precise color. If rendered in 32bit/float, channel (EXR), it should be rather simple to replace these colors or set the unwanted to neutral with a simple Colorize/Gradient.

The points of each polygon can be animated, as I have done it.

In the same way, one could create single quad polygons between two Spline and animate the Splines to get the mixing color fields.

If I get another idea, I will add this. But this was all I could find after many hours of searching.

All the best.

P.S.: Perhaps this little “sketch” is working.
https://www.amazon.com/clouddrive/share/s4AMBpSgzL6fzPkXb3PmJszpDrJRNNFx3SsVbJtrvps

Let me know, as the “crossing the line” destroys the polygon.

Hey Sassi!

These are both really interesting.  I really like both approaches and I can see how they could work really well.  The first one seems more manageable with a large amount of shapes.
I’m going to play around with these (and study the ray collision node, which I never used).

Thanks for looking into this!!!  Really appreciate it

Thank you very much, Alex, for the reply.

There must be something else, and I hope a light bulb will switch on in my head at one point. With just a single crossing point, I had set up an exploration to find the shortest distance of the samples (samples were given to each spline and evaluating the distance each time). The shortest distance, preferable zero, would win. This can end up in thousands or tens of thousands of probes for one crossing point. Since you have only straight lines here, there must be a formula that is faster to use.

My best wishes for your explorations.

Cheers.