So to learn Moi, I decided to design a 'blast rifle'. I made the outline from various intersecting lines, arcs, and splines, trimming and joining as I go. Then, I took the final stock outline, and tried 'extruding' it, and one part of the rifle stock comes out looking 'twisted'. The surface in that section also doesn't look curved, but 'flat' when rotated through some angles. I tried recreating the problem using a simpler outline, but have so far been unsuccessful.

Hmm, when I export into obj, and look at it in the subdivision preview, the generated polys look fine.

HI Crusoe - this is a display problem, your actual geometry is fine.

On certain "S" type shapes the display mesher can get confused and not add enough polygons. This doesn't happen on the export mesher because the export mesher does a much more careful job of analyzing the shape of the surface, but the tradeoff is the export mesher is much slower.

There is a setting you can turn on to fix this up - go to Options and check "Add detail to inflections":



That will increase the density of the display mesh in certain areas and give more detail to the display. I'm thinking of switching this to be on by default, the only reason it is not on is that it creates more polygons which can slow things down a bit on complex models.

- Michael

Hi Michael,

I'm seem to be having a problem with the "Extrude" in the 18 Jan version.
Being new to this, I'm not sure if it's just me (more than likely), a display setting or a bug??
I've already tried the "Add detail to inflections" with checked & unchecked, it made no difference.

Started trying out the new "Image" feature & it's great so far, which no doubt you'll add to & improve on.
Sketched out all of the birds outer shape with no problems, then Joined all lines together.
But I've run into a problem while trying to use the Extrude?
I've been able to Extrude the top section, but the bottom section doesn't seem to work properly??
Could you try the lower section & let me know? Extrude, with Caps checked, a distance of 0.5

regards Colin

Hi Colin, thanks for testing out the new image backgrounds. That's quite a long curve you've got there, you will probably like it once there is an undo for the last point built into curve drawing.

Anyway, there is one duplicated point in the long curve, at the end of it:



This one stacked up point is causing an error in the mechanism that determines inside versus outside of a shape. If you delete that one point (I have attached a version with it removed), it should then work ok.

It's unfortunate that stacked up points can cause problems since it is easy to snap them to each other... Eventually I hope that the geometry library that I'm using will be more tolerant of stacked up points, but it will probably be a while before that will happen.

- Michael

Hi Michael,

Thanks for that, I kind of figured it'd be something simple that I'd done!!
Especially as I could Extrude the top section with out any problems.
In future, I'll try to keep an eye out for those pesky duplicate points :)
Any advice on how I'd be able to track them down, should something similar happen again?

regards Colin

> Any advice on how I'd be able to track them down, should
> something similar happen again?

There isn't any especially easy way - for this one I went through and dragged each point to check. If you can drag a point away and then you see another one underneath it, then that's a stacked up point.

But a lot of times a stacked-up point will not have quite such a dramatic effect - sometimes it won't cause a problem until you try to do some kind of boolean or intersection operation in that area.

I wish I could just automatically process the curve to get rid of stacked-up points, but taking away a stacked-up point does change the shape of the curve in that area, so I'm kind of hesitant to do something automatically that changes the shape... Although I suppose I could just move it by a small amount like 0.01 units or something, that would have a pretty minimal change.

I guess that the way the points get stacked up is when you have 2 curves near each other and you drag the second-inside point and then it gets snapped on to the end of the other adjacent curve, I suppose it is also possible to detect this and not do the snap in this case, that could also help.

- Michael

How about for a curve, when you select "Show points" if it detects stacked up points, display their handles in red? If you show the stacked points, thats good enough.
And if it's too expensive to run all the time, a "Check for stacked points" command would be useful to have.

HI Crusoe,

re: Stacked points in red.

This is a great idea! I don't think it should be hard to do, I will see if I can give it a try tomorrow.

- Michael

In the next beta, when you have points stacked up, a red frame will appear around them. This sticks out pretty well so hopefully it will draw your attention to that point to unstack it. Here is what it looks like:



Thanks Crusoe for the great idea!

- Michael

Hi Michael,

That solution looks good to me :)
Much better idea than having to move each individual point to find the culprit.

regards Colin