Here’s a little problem I’ve been searching for a solution to for some time. Sorry if this has already been answered, but I couldn’t find it if it has.

When you have intersecting geometry, particularly with circles, I would like to know how to force SU to snap to the point that I want, vs the point it wants. For example, if you have a line that intersects with a circle, you have an endpoint, an intersection, a quadrant and a center snap point. Most of the snap points are generally easy to obtain… except the center point. Waffling the mouse around and around trying to persuade SU to find the center snap ultimately ends in frustration and/or drawing a new object just to get the center point. In many “other” CAD programs, you can override the snap to be picked by typing, or shift+right clicking to get a snap menu… allowing you to ONLY choose center points, etc. just for that command. Is this a SU thing, or am I just wishing?

To get the circle centerpoint you just need to first go over one of the circle’s segment endpoints .

Right… you hover over an end point, and both the end point and the center snap light up… you move away from the end point and the both disappear. You hover over the center of the circle, and nothing happens. How do you select the center snap, and not the end point snap when hovering over the end point to get the center?

Something is funky…I get center snaps quite easily:

more so because you just created the circle you were gonna look for the center point.

But I can usually find the center point after you hover over one of the endpoint of the circle as @ely862me said.

Maybe the circle has been modified and no longer is a circle?

Yes, there are various drawing operations that will “deconstruct” an arc so that SketchUp loses the metadata telling it the center and radius. You can see that this has happened if you click on an arc and you get just one edge. Once the metadata is gone, SketchUp can’t infer the center any more.

Thanks for all the replies. I guess it’s the lost metadata that is my issue. For example, when I draw a circle (which self-fills), then proximity to the filled area give me the center snap, as slbaumgartner illustrated above. However, once the fill is deleted – or, as is more often the case, when line geometry is imported from a .dwg (I use datums and/or circles as my base points to line up imported graphics), then the center snap is very difficult to obtain. I think my solution is to draw a new sketchup native circle over my imported target, snapping to the edge of it, and then I can easily obtain the center point. thanks again!! Cheers!

JP.

Hi SLB.

Some of us are new or intermediate to SU, we sometimes encounter problems that cannot be explained by simple circles. I like what you showed us but I’m sure it wasn’t anything like this that JPB was trying to explain. What you did is kind of really easy to replicate.

But if you do a circle and afterwards you create a tube from that same circle and then make it a component, if you do a second tube the same or another diameter and try to connect surfaces from one quadrant to the quadrant of the second tube, you won’t be able to select a snap point exactly at 90degrees (quadrant) to be able to align all tubes (circles with a length like a wire for example) to an adjacent tube. I tried a lot of things to get it to snap to quadrant and never found a way that SU would do it by itself right out of a new drawing.

So when we zoom on the surface of the circle at the end of the tube, we can see that the circle is made of multiple lines so none of them are at the 90degrees (quadrant) snap point. Which is pretty annoying. Like for the “Hover” thing. if the component is not selected and you use the move tool, when you hover over the center, the center snap point doesn’t come out. But when you hover any circle side points (none on the quadrant but at the end of a circle line around the circle) and then come back to the center, the center snap point appears. This is another annoying thing for me. I’ve used AutoCAD for many years and know it inside and out. I know I have to rewire my neurones to be able to use SU but sometimes, I need to go away to get the steam out. It is so frustrating. All of these are so simple things to fix. But I’m writing to you all because I’m sure you will be able to show some stuff I don’t know that will fix my problem. If not, it will answer my question about if the time spent on SU is worthwhile.

For now, I go to the Entity Info Tray and modify the number of segments to a 1000. Which will slow the process of drawing but it is the closest thing to what I need. For me it should be at the best resolution when we open a new drawing.

I’ll be waiting for your answers Guys.

Thanks.

I’m not certain that I understand what you are saying, so please bear with me.

You can find any number of topics on this and other discussion boards about how SketchUp’s geometry representation includes only finite straight edges and finite planar faces bounded by closed sequences of edges (“loops”). And about how SketchUp has no higher-order geometric objects such as real curves or curved surfaces that you can find in other parametric modeling applications. These facts are fundamental to how SketchUp was designed and how it works; adding real circles or things like NURBS would require a very deep rewrite of the entire thing, not just an easy extension or fix.

So, yes, there are shapes that SketchUp can only approximate and operations involving those shapes that it can’t perform exactly. It comes down to understanding what SketchUp can do within its approximation and toolset and adapting expectations to the best approximation available - which can usually be good enough for all practical purposes.

I assume by your talk about “quadrants” your goal is to create something akin to this:

If you look closely, you can see that those two cylinders actually touch along a side edge from one of the vertices of the end circle.

There are two things to realize in creating such a structure:

- Only the vertices of the circles lie on the mathematical abstract circle. There are no points on the rest of the abstract circle, so the SketchUp objects wouldn’t touch even if you could grab or snap there. So the only places you can make the cylinders “kiss” is along a face or edge.
- When you draw a SketchUp circle, the first click sets the center point and the second click sets the location of the first vertex of SketchUp’s polygon approximation. If that second click isn’t along an axis direction from the center, none of the circle’s vertices will be exactly on that axis (which is what I assume you mean by “quadrant”). When that’s the case indeed you can’t pick a vertex that is exactly on the quadrant because there is none. As you wrote, you can get closer by increasing the number of segments in the circle approximation, but you will never be exact and you will have made your model quite heavy.

For a lighter-weight model, you can address the problem in either of two ways. You can draw the original circle/cylinder carefully to make sure it is oriented the way you require, or you can use the rotate tool to reorient the circle/cylinder after the fact to bring it into alignment. Then if you move one circle by grabbing a vertex and moving to the snap at a vertex of the other, you will have them touching as closely as SketchUp can do:

this is possibly, your biggest mistake as only segment counts divisible by 12 will give you 4 x 90˚ selection points [cardinal points]…

normally when you select a ‘cardinal’ point with the ‘move’ tool the circle will ‘scale’ so you need to pre-select the face, then the point for a move…

it make more sense to position 12 segment circles and then up the edge count…

john