Aligning objects with each other

taz

I can't find any basic alignment tools (such as align centre, etc).

How do I align the centre of a square to the centre of a circle so that:

a: I could move a smaller square on top of a circle so that it is exactly central
b: I could start drawing the circle from the centre of the rectangle

I can get the inference to find the centre of an axis, but not the centre of two axes.

I'm using these shapes as simple examples, but it would be great to have a solution (preferably not involving scripts) that works with any shape in 2d or 3D.

Thanks

dedmin

http://forums.sketchucation.com/viewtopic.php?f=323&t=20233&hilit=align

Jean Lemire

Hi Taz, hi folks.

To get the center of an Arc, a Polygon or a Circle, hover the cursor over any endpoint on the curve untill you get a pop-up message stating "endpoint", then, move near where the center should be and you shall get a pop-up message stating "center".

To get the center of a square or a rectangle, hover on the midpoint of a side untill you get a pop-up message stating "midpoint". Immediately do the same with an adjacent side. Then, move near to where the center should be and you shall have a dual midpoint inference.

Once you have grabbed an item by the center of a face, you can place it over or under the center of the upper or lower face of another item, using another inferencing operation. If the object being moved is hiding the object on which you want to place it, you can switch to X-Ray mode to be able to see and inference geometries through objects.

These points as really important if you are to do easily some complex modeling with SketchUp (SU).

The first point to remember is that you can switch viewing mode even in the middle of any drawing, scaling, moving, rotating, etc, operation. Not only that, you can change scene, orbit, pan and zoom, etc.

The second point is multiple inferences. They are one of the most powerfull feature of SU but also the most underused, if not totally unknown by a lot of users, judging by the number of questions regarding modeling operations. Also, don't forget that you can lock inferences with the SHIFT key. This is also a powerfull feature of SU.

Of course, if you are not having success immediately with double inference or in getting the center of curves, you can mark these with a "Point at center" or get the center of a rectangle by adding a diagonal and using its center.

Just ideas.

taz

Thanks a lot folks

August

@jean lemire said:

To get the center of an Arc, a Polygon or a Circle, hover the cursor over any endpoint on the curve untill you get a pop-up message stating "endpoint", then, move near where the center should be and you shall get a pop-up message stating "center".

Hi Jean,

It's not working for me with a polygon. Obviously I'm missing something.

I have a shape that used to be a circle but isn't anymore. It's now a 240-sided polygon. I can right-click and convert it between polyline, polygon, curve, and exploded, but I cannot convert it to arc or circle and no matter what state it is in, I cannot get a popup saying "Center".

Jean, when you say "hover the cursor" I don't get any Endpoint popups if I just have the select tool, so I'm using the Line tool. What tool are you using?

I made sure the Extensions > Ruby Script Examples plugin is installed, but I don't get the Point At Center option in the context menu for the polygon. I do get it for arcs/circles.

If there were a Draw Perpendicular tool I would just cross a couple of diameters.

This is such a basic operation, yet it's stumping me tonight.

Suggestions appreciated.

Thanks,
August

TIG

You can only find the center of an arc/circle/original-polygon. Other curves that used to be these things have become just 'polylines' or plain 'lines' [edges], and so no auto-center-finding is now possible...
Except there are tricks - like drawing two guide-lines parallel and through two of the curve's full-sized segments, then rotating them about the segments' midpoints 90 degrees - then they'll intersect at the original arc's center...
Chris Fullmer also made a script to find the center-point of an 'exploded' arc... see this link http://forums.sketchucation.com/viewtopic.php?p=155504#p155504

Jean Lemire

Hi August, hi folks.

Like Tig wrote, if a curve (arc, circle or polygon) have been exploded, you cannot get the center of it with an inference and of course, the function allowing to get a "Point at center" will not work.

As for pop-up over endpoints, it shall work with any tool that can hook to an endpoint.

Maybe you have a video card driver problem.

Just ideas.

August

@tig said:

... Chris Fullmer also made a script to find the center-point of an 'exploded' arc... see this link http://forums.sketchucation.com/viewtopic.php?p=155504#p155504

Thanks TIG,

Chris' script is working great for me. It's also a very readable script for learning a little more Ruby. The function "cross" in it I assume is "cross product" which I remember as having something to do with vector math, so I'll have to look that up to fully follow the inside workings of it. But it's clear that it works by the same method as described for manually above -- create lines perpendicular to the centers of the two selected edges and place a point where they cross.

Thanks again,
August

TIG

vector1.cross(vector2) does indeed give a vector that's perpendicular to them.
As you say, most scripts actually replicate what you could do manually given enough time and effort - it's just that they can do it quickly and cleanly 'behind the scenes'...