Hi

I have done something to my MoI , that now I can only extrude in the Z direction.

In Top view I draw a Straight Line in either X or Y , it will only extrude in Z. I restarted MoI same thing, I reset Cplane, still no change.

I have no idea what I have turned on or off, MoI V3 Nov Beta

Cheers, Steve

Hi Steve, it's because you're trying to extrude only single lines. A single line all by itself does not really define a unique plane, there are an infinite multitude of planes that go through it at different rotations.

When there is not a unique planarity to an object it will default to extrusion in the z axis - that's how it has always worked, it's not any setting that has been changed.

When there is no automatic plane that can be determined for an object you need to push the "Set dir" option if you want to change the direction of extrusion.

Lines along the x and y axis directions are particularly troublesome because not only do they not themselves define a single unique plane, but they're also simultaneously on the view planes of multiple ortho views as well, like a line along the xaxis direction is on both the Top view's drawing plane and also on the Front view's drawing plane at the same time.

- Michael

There are some things like booleans that do extrusion in them that use the relation of the line to the object being cut to determine an extrusion direction.

That's why a boolean with a line like these works:







But if you're just doing a regular extrusion of the line rather than using it as a cut there isn't a secondary object to help it pick which direction to go in.

I guess I could try something like look at what viewport you clicked in and if you clicked in the front view then make it go normal to that view...

Currently instead of using the "Set dir" you may want to instead just draw a little additional leg onto the line then that makes it define a single plane.

- Michael

Hi Michael,
The automatic "set normal" may be problematic in some cases, like where there is that ever so slight "out of plane" and then bad geometry can be inadvertantly made. I would have that as an "option" (Well, that adds UI). I think it best to have the set dir be the main thing to learn. It keeps the control and also forces direction in cases where it's not being paid attention to....

2 cents.

Hi Burr, but if you have something out of plane what difference is it whether you set the direction to what you thought is the plane normal or whether it is automatically set? Won't you get the same extrusion result in either case?

Currently for something that's not just a line but not planar it will calculate a "best fit" plane for it and use the closest world axis direction to that best fit plane as the direction.

So for example a curve like this which has an out of plane wiggle in the bottom area:



Will get this default extrusion direction of the world y axis direction:




This does not happen for lines though, there is not really the same concept of a "best fit" plane for just a single line, any plane tilted at any angle can contain the same line within it so there isn't any one plane that minimizes the overall distance of the curve to it. So determining an extrusion direction for a line is a different kind of a thing. It just uses the z axis for that case currently.


- Michael

Oh my bad. "Plane normal", which makes sense. I thought it meant "object normal". Currently, the CAM program I have has an "object normal" selection, which I rarely use for the stated reason. I set a cplane and then use the "Z" option. (CAM does have different circumstances to control)

As long as it was using one of the planar directions would be correct, then the "set dir" can be enabled if "you knew" you needed it to go somewhere specific.

Hi Burr, oh I guess you were talking about the case where the curve is actually planar within tolerance itself but at some angle to one of the main axis directions. You will get a default extrusion direction that follows the object's own plane normal in that case.

The one I showed above is for when the curve being extruded is not itself planar within tolerance.

Note that by having each object follow its own natural extrusion direction it allows things like this to work all in one extrusion step:




If it asked you for a single extrusion direction at the beginning of the extrude it would not be possible to get the "batch extrusion" result above from just one extrude anymore.

- Michael

Hi Burr,

> As long as it was using one of the planar directions would be correct, then the "set dir"
> can be enabled if "you knew" you needed it to go somewhere specific.

Sorry I got confused - I was thinking of the case where the object being extruded is not itself planar. For that case it does pick a world axis direction as the default rather than some skewed direction.

But if the object that you are extruding is itself planar within tolerance it will use that object plane direction as the default like you were thinking.

The more that objects use their own built in properties helps make things work with multiiple selection "batch mode" type stuff.

- Michael

If you have an object that's planar within tolerance but on some slightly angled plane, I'm not really so sure that making a world-axis extrusion from that really fully fixes the problem...

Probably the profile ought to be flattened in that case. But it's kind of hard to do that automatically because the question then becomes how much deviation do you allow before stopping the auto flattening from kicking in. If it kicks in too easily then you can't make something at a slight angle when that's what you actually wanted to do.

I've thought a little bit about having some more information in the properties panel for whether the current selection was planar or not.

- Michael

Hi Michael

Thanks for the answer, I can't believe that in over 1 year of playing with MoI, I never noticed this behaviour before :(

Got it. I've been really looking forward to the "extended properties panel". i think this will be many answers/wants in one...I DO think what we've been getting is more deserved, or warranted though...