Splines

Yes, splines again.

I have asked before for these, but will ask again, as frustration with the splines as got the better of me.
For example, with "Spline vertex > Slide"

Control of spline tangent orientation(twist) at vertex(control points).
As it is now, we have automatic creation of the tangent orientation(twist) with no way of editing. At times, those orientations are anywhere they want to be, and if attempting to create anything other that a tube, in can be a waste of time/effort. Yes, you can add a "Twist" and attempt to control via "Twist modify curve", but that in itself is a nightmare.
Please add control of the tangents orientation(twist), so that I can select a vertex and rotate its orientation(twist).

Auto Naturalize.
I did ask for the ability to stop that, but the option was only ever added to "Tweak". That can be workable, but with no axis constraint, a need to keep changing view for accurate editing.
Another point, is that when editing "Modify curves", there is a need to keep exiting the main function to enable Tweak to adjust the curve, so it can be a case of keep changing tool/function for tweaking (otherwise, moving a vertex will cause auto naturalize, (unless it is a line list)), when there should be a way to stop auto naturalize without all the swapping about.

I thought I would post an example from Blender.

Default curve twist method is controlled via options of Tangent/Minimum/Z-up



viewing the curve, you can see (what appears to be) arrow heads along the curve, those shows direction and orientation(twist) of the curve.
You will also see, that while editing, all tangent handles are shown, it saves having to first select a point before selecting its handle.



To edit the orientation(twist), I select a point, use hotkey for function, and rotate the twist at that point. Interpolation is made between the points from that adjustment/edit.



For each point, there is also the option to set that specific point for handle type, and if it should be automatic (naturalized) or not. (the curve can be created and edited at the same time).

Update.

For the "Auto Naturalize", the options for that have been moved from "Spline Vertex > Tweak" to "Edit > Options > Spline Transform Options".
There are 2 options:-
1. Auto Naturalize Whole Spline
2. Auto Naturalize Selected Point
Both can be disabled to completely stop any "Auto Naturalize".

Those options now work on all splines in any Tool/function.

Already saving me time.


Many thanks to you IStonia for taking the time to implement that.

Try this one
http://www.digitalfossils.com/Download/NVil-Mar-17-14.rar

  * "Custom Tangent Mode" is added to spline "Tangent Tool". Custom tangents won't affect spline shape. They will be used for related mesh operations.
  * View > Display > Show Spline Tangent Flow.

Hi IStonia,

I have not had much time to test, but there are some issues.

The tangent direction and magnitude are controlled by the tangent handle. The extra control needed is just for the twist/orientation around the tangency. For example, for the splines, Y axis(tangency) points along the spline, the XZ plane is the twist plane. So when adjusting the "Twist", there should be a lock to make sure rotation is only around the Y(Tangent) axis. (In Blender they just show a dotted line from the control point(vertex) to the cursor and give feedback on rotation made).
When adjusting the twist, I suggest the handles should show, but the manipulator should be on the vertex selected, and rotation locked to [around the] tangent axis only. Maybe an option to set manipulator for twist adjustment?. Second thoughts, there should be no need for an option to change manipulator for twist, it should do that automatically when you enable custom "tangent twist". The options for handle selection could be grayed out.



Quick tests do show problems with interpolation(smooth transition) between vertex, but will test more and post result later.
The arrows for the flow, they appear to be erratic and not showing correctly. But will check more.

Many thanks for looking at this.

Hi IStonia,

I can now see what you have done. You have enabled (custom) changing of the direction and orientation(twist) of the tangents. Unfortunately, that makes it almost impossible to control and get accurate (and smooth flow) results. Please see my previous post concerning control of the twist.

I will add a couple of pics to show the problem.

I create a planer 3 point (naturalize) spline.
(I want to adjust the middle tangent)



I select the middle vertex, enable "Vertex tangent" Tool with option "Custom tangent mode".
Whatever I do with the manipulator on the tangent handle, move or rotate it, even a fraction, the tangent(flow indicator) on the vertex changes and points upwards.



After some time, I can get the tangent direction re-aligned with the spline, but that is on a simple planer spline. If it was a 3d spline, It would be extremely difficult without first adding a reference(for original tangency) from before it changed.


I wanted to test results using "Spline Vertex > Slide", but the results from Slide are still quite bad at times when using curve tangents on 3d splines.

Try this
http://www.digitalfossils.com/Download/NVil-Mar-22-14.rar

Two more options are added.

Hi IStonia,

On first check, yes, much better, I can now control the twists without loosing the tangency.

I have a couple of hours spare later, so will fully test, check results, and post back.

Many thanks.

Hi IStonia,

When adjusting the "Twist" on open splines, there appears to be an issue when attempting to rotate above 90 deg in either direction. If "Auto adjust tangent flow" is enabled, the twist (at selected vertex) will flip 180 degrees(when attempting to rotate past 90 deg). If "Auto adjust tangent flow" disabled, the flow on each side of the selected vertex being adjusted will flip.

When you can find time, could you please check.


I am not convinced that there is a need for a full "Custom tangent mode", only the need for the extra option to "Twist". What is your thinking behind that?

Try this one
http://www.digitalfossils.com/Download/NVil-Mar-24-14.rar

The "Auto adjust bitangent" is to ensure the bitangent of adjacent spline points' bitangents don't point to opposite directions. So you may see flipping when adjusting twist.

The twist is limited to 180deg on each vertex (if more, the twist reverses), but if that is a limitation, then OK.

It is looking quite good now. Much better control, and no problems with losing tangent from spline directions. I like how we can now adjust twist and the tangent direction with rotate manipulator on vertex.

Thank you very much for taking the time to implement.

Hi IStonia,

I forgot to mention the spelling mistake in the tangent popup. "nt" is missing off the end of "Out Tangent"(see pic above)
-------------------------------------
A bug came in at some time(before you added the twist option). If you attempt to "Spline Extrude" open splines, there is an "Unhandled Exception" (I will post error file if you cannot reproduce).


Thanks,

Check if fixed
http://www.digitalfossils.com/Download/NVil-Mar-26-14.rar

Bug is fixed, thank you.

Hi IStonia,

While still on this subject.

When the manipulator is set to "Orientation > Selection" and a Spline vertex is selected, the actual orientation the manipulator is set to, is the spline objects pivot orientation (Object orientation).

I find that to be incorrect.

Could you please verify?

Thanks,