Trying to Master curves... some load of head bumps :)

[probiner]

Hi, still grasping SI and focused on Curves this week as I've been modeling locations and they seem perfect to sweep roads, distribute light posts, etc. But some issues came along:

A - How to draw bezier curves like in Illustrator? When drawing, I can't click and drag to place an anchor point and also manipulate the handle after. Also at each anchor placement the previous handles change quite a bit (changes the last, which changes the second last, etc, decaying). I also can't drag an anchor or handle while drawing a Bezier Curve. I guess for tracing aerial images it's probably better I stick with Illustrator and Import EPS no?

B - Project weights from closed curves or some other property to control emission. Co-worker uses a MAX plugin called Forest. He controls the scale of instances from 0 to x with a closed curve. Outside of the curve area they have size 0 (don't show), inside they have X and he can also control the falloff of the 2 areas blending. How to replicate it in SI.

C - How to smooth a curve? I wanted to either smooth the alignment of the handles and/or smooth the length of the handles. How do you guys smooth curves?

D - Curves have no Up-Vector per knot. So if I want to do a roller-coaster with some rolls at some knots I don't know how to do them. Having a "Set Envelope" with an array of nulls prior to a Curve Deform can hack something, but if I twist too much it breaks.
Would be interested to know this for modeling and also for rigging say chain or so.

Any other tip or reference for how to best work with curves?

Thanks in advance
Cheers

[Mathaeus]

A: I'd say, don't be confused with Bezier name, you can see somewhere in interface. SI curves are NurbS curves, all the time - they can emulate Bezier curve, but that's all. So, if you are going into comparisons, Rhino 3d could be reference, really not Illustrator. And that's how nurbs curve is drawn in Rhino, too. SI won't be a winner into this comparison when it comes to, everything... but that's another story.
B: I think there's similar feature in Milan Vasek's Scatter tools.
C: If I understand, it's XSI Smooth operator. These operators works with points, almost whatever works with mesh, should work with curve too. Smooth, ShrinkWrap ( to something else), Envelope, so on.
D: Before ICE I'd use Deform By Nurbs surface, created with help of script for re-sampling the curve, to get a nice distribution before lofting.
I think there's still ICE compound called "Dual Path Deform" or like, which uses one curve for deformation, another for up-vector. No big deal to modify this one, let's say, to use normals of some mesh (easier to visualize). Or just fixed, global up vector.
SI "Deform by Curve" operator uses something along line of Frenet Frame interpolation. It won't flip at some point, but, not easy to predict where it will end up - unless entire curve is on plane. This is more a convention, that's the way to use only one curve and nothing else. Max does it in same way. As I said, there are ICE operators , around.

[probiner]

Thank you Matheus for taking the time to answer each.
D is definitely the most tricky

Kevys Curve tools are a must.

Scatter Tools (great) do use curves, but I was looking more to a way to generate a weight map. Did it by meshing a closed curve and raycasting in to the ground and then bluring the weight with the Smooth Weight Compound. So it's mostly tackled. Only issue now is avoiding Instances to self intersect. Anyone tackled this one?


Other than that and getting familiarized with many details it has been a very nice experience.

Cheers

[Mathaeus]

Only issue now is avoiding Instances to self intersect. Anyone tackled this one?

There are few ICE setups or nodes for 'dart throwing', like
this one or this one - you'll need to use them as emitter, instead of what you already used.

Imho yes, distribution seems to be most important for good look, somehow, dart throwing method looks really close to natural forms.

[probiner]

Many thanks Matheus, so much to try and learn

Started to make roads today and quite happy with the setup I came up with:

Make the road center-line path. get a square closed curve and clone it several times. Constrain the clones to the center-line path with percentage L(100). So I have a master profile which controls the general look of the clone profiles, and each cloned object can be stretched with Local, or even displaced or rotated in component mode . The just Loft using all clone profiles. Very happy with the level of control. I can manually roll the profile and the loft adjusts. Have to test this for animation purposes, but for roads for now it's awesome. I like how things in SI can be very rational.


One last question:
- How do you know the start and end point of a curve just by looking at it. Lately I have to doo a path constrain on a dummy geometry to find out. No visual cues?

I don't feel just a complete noob anymore.
Thanks! I'm hyper.

[probiner]

So no master yet but a lot more comfortable now.
Kevys Curve Tools helped a lot. rtRenamer as well.

Surface Constrain is quite nice for upvector control.


Anyway silly scene attached. Tweak Tool on the Curve to control the road path. On Local rotate on Z and Scale on X the 1D Red profiles and also Scale on the X the Blue profiles.

I just wished Deform by surface was easier to keep the original mesh proportions and just slide the object.

Might need to take time to try out your compounds Matheus just trying to find a UVless solution for now

Cheers