OK I have found the good solution but I am totally perplex
My object is on the ground
The curve is on the ground

The axis on the left corner are the default current axis of the curve + object
I don't find any coherence between them and the good result axis found for have the object sliding perpendicular on the curve on the good position!
I must make many try / error for find good result, and I am not satisfy of that
I must miss something for an easy find!
(always with the same previous file uploaded)

Hi Pilou,

> if I take the same orientation of the orient function
> than my object that works on the top curve surface,
> that don't work for the single curve!

You mean snapping on to the edge curve instead of snapping on to the independent curve object?

Yes, that's normal to get different behavior between those cases - the edge curve knows that it is part of the surface and anything that snaps on to a surface aligns the target z axis frame to the surface normal. When you snap on to a curve that is not part of the surface it will instead align the z axis to the curve tangent.


> That is curious that we must take some different regulate for a
> curve who have same position except a move displacement

The difference is that one belongs to a surface, and so the direction is aligned to the surface - the other one that does not belong to the surface does not have a surface normal to align to and instead aligns to the curve tangent.


> In the file , I want move my object like your cone :)

Just put the view into a similar direction as what I shown above and then it will behave like that - here is an example with your object:



Is that what you want?

But what is the final position that you want this object to have? If I knew the final result that you were looking for it would be easier for me to give you some steps that would give you that result.


> I must find a tricky way for not have hesitate to choose
> the good orientation of the axe of the Orient tool!

Don't worry so much about what things look like while you just move the mouse around - just focus on the final spot where you wish to place the object, and if the position in that final place is reversed from what you need just click this checkbox here to flip it:



- Michael

Hi Pilou, I'm sorry but it is very difficult for me to understand what steps you are using just looking at your one single image there.

> OK I have found the good solution but I am totally perplex
> My object is on the ground

So there are 3 objects in your file, are you talking about this one here:



If so then can you show me what spot on the object you are clicking on to make the source frame?


> The curve is on the ground

Are you talking now about the independent curve object, or the surface edge curve, because you will get different behavior if you use those different ones.


Again, could you please show me the final result that you are looking for, because that is not clear to me yet.

Is this the result that you want to get here? :



If both objects you want to position are in the same plane, you may find it easier to use the Orient Line to Line tool instead of the full 3D orient. The orient line to line version is on this button here:



That tool is more simple because it doesn't involve orienting the full x,y,z axes between things, you instead draw 2 lines to do the orientation.

This works best when the lines are in the same plane, like in this case where you have both things you want to align on the world x/y plane.

So for Orient line to line you would pick the following points to orient your object (here I turned scaling mode to Scaling:none):



So using orient line to line, I picked the first 2 points on the object, the first one on the midpoint of the edge and the second one further along it to define the base line, then the target points on the curve, first target point on the curve to control the placement, and then the second point snapped on to the curve tangent to define rotation.

That is probably an easier tool for you to use for this case because it has less need to worry about which directions all the x,y,z axes are pointing at which you need to be aware of (and sometimes adjust to get what you want) for the full 3D axis orient tool.

- Michael

Hi Pilou, so maybe some of your confusion with the 3D orient tool is that you're focusing on edges of your base object, but by default the primary thing that is actually aligned to is surface normals if the object being snapped on to is made up of surfaces.

So for example placing the orientation picker x/y/z location to this spot here:



The default thing that will be aligned with is actually this surface here:



The yellow line here shows the surface normal direction of that yellow face:




So that's the direction that by default will get mapped to the target position's z axis, and if you place the target position on to a standalone curve, the target position z axis will align with the curve tangent.

If you wanted to align some other direction than that, you would need to adjust the base axis frame, you can do various things like rotate the an axis by 90 degrees around another axis until it has the orientation you want to use.

But instead you may find the other Orient Line To Line command as mentioned above to be easier for cases where you want to position 2 things that start out all in the same plane.

- Michael

Thx for the detailed informations

Sorry if i was not clear in my explanations
The object was not in the good orientation in my previous file :(
I was fumbling and deseperate to not find the good solution!
(so the false image and file! :)
(but thinking that is possible to start from any position to anotehr one
--> perpendicular abode the curve)
Object on the top curve surface is the result wanted

So what must be the deductive reasoning for ovoid to test all orientation of the tripod axis :)
Of course I will exam all your infos above!

Here the new file! :)
http://piloumaison.weebly.com/uploads/3/6/2/0/3620514/slide_on_curve1.3dm

Is that more clear? :)

Of course the line / line with no Scaling is cool but i will whish to slide on the curve for some reasons :)

Hi Pilou,

> Is that more clear? :)

A little bit... :)


> Of course the line / line with no Scaling is cool but
> i will whish to slide on the curve for some reasons :)

It is possible to get the slide along curve, but you have to position the source frame to the correct position so that it will map to the natural target location on the curve.

The main thing to focus on is that whatever direction the z axis is pointing towards in the source orientation, will get mapped to the curve tangent direction in the target placement, since when snapping on to a curve the axis is placed with the z axis along the curve's tangent.

So for example with your last image, if your source orientation is positioned with its z axis like this (z in red here):



When the target position is placed on to the curve, that same direction will be mapped to the curve tangent, here the curve tangent shown in red:




So the red line in the first image maps to the red line in the second image....

In other words, the z axis of the source position is what will end up matched to the z axis of the target position. Similarly the x axis of the source position matches to the xaxis of the target position and same with y.


The reason why it is mapped in this way for default positions is that it makes it easy to position a planar curve perpendicular to a different path curve.

But if the default mapping does not do what you want, you need to adjust the orientation by flipping some of the axis directions around instead of only using the default orientation.

My advice is to not worry so much about getting the "slide along curve" motion just by itself - instead try to focus more on what final position you want to get as the end result. If you are focused on the final position more it means you can do some axis rotations on the target position to get the final position how you need it.

I'm still not sure if you are able to get what you need now or not - doesn't the orient line to line tool give you an easier way to get the final position you wanted for your particular case?

- Michael

< So for example with your last image, if your source orientation is positioned with its z axis like this (z in red here):
This is my result of manually use the Function Orient! If you see on the image the little lift corner you will see the default orientation ;)


The line/line is perfect for one position on the curve !
(little trick) just take the first point on middle on the baseline objet, the second anywhere to the end line base object, and you will have easily the postion on the curve with a perpandicular helpers line ;)

And then call the normal orient for slide the object on the curve! Bingo!

But, now , i have learning by heart the tripod position for arrive on a curve // on the ground for win a using step function! :)

So now I am a little more strong for make video about the subject!
Thx for the help and sorry for my unprecise first image!

Just a question : does the last tripod of function "orient" position is memorised when you closed Moi?

And regulate the size of the tripod of the function Orient?
In the moi Ini?

and this one!
I have all disable Snaps except "On", (because I want slide on the curve) in any menus, in any options

But there is always trouble when I pass over the "ghost forms" of the original object position when I slide the object on the curve!!!
How avoid that?
If I make Alt, I am not more on the curve! :)

Hi Pilou,

> Just a question : does the last tripod of function "orient"
> position is memorised when you closed Moi?

No - in general points that you pick within some command are not remembered between sessions, and orient is no different than any other command in this regard.


> And regulate the size of the tripod of the function Orient?
> In the moi Ini?

No, there is not currently any setting for that in the moi.ini file - those line are scaled so that they will be a size of 150 pixels on the screen though, so they will maintain a constant size whether you're zoomed in or zoomed out.


- Michael

Hi Pilou,

> But there is always trouble when I pass over the
> "ghost forms" of the original object position when
> I slide the object on the curve!!!
> How avoid that?

You could move the original object off to the side somewhere so it wasn't directly on top of the area that you wanted to orient it on.

Or another possibility is to assign a name to your object and then while you are within the orient command you can go to the Scene browser Objects section and hide it and the wireframe outline of it will then be hidden.

- Michael

Thx for all these precisions