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Measure arrows, vectors and axes

Posted: Sun Aug 25, 2013 3:19 pm
by Eriku
In some Blender jobs I need to draw lines and arrows for measure settings, for drawing an axis system, for discussing or demonstrating a vector problem etc.
But the arrows that I find in "Add/Empty" are too simple and there is very little room for adjustment, as far as I can see.

I would like the possibility to
** adjust width and length of the shaft and the arrowhead independently
** choose color of the arrow
** define an orthogonal right hand axis system with adjustment possibilities as above
** choose arrowhead in none, one or both ends of the shaft

Can this be made in Blender?
I would not be surprised, but so far I have not been able to find it.
I would appreciate some help in that direction.

Posted: Sun Aug 25, 2013 8:01 pm
by brasshat
What I do to achieve what you are looking to accomplish, is to create reference objects, for which I reserve layer 2. I will use anything that fits the purpose as a reference object, but is typically a cube mesh. I scale it to the length width and height needed, and rotate it as desired. I apply three different materials to the cube, one for the faces aligned to the xz, one for faces aligned with the yz, and one for faces aligned with the xz axes. When I need the reference object, I make layer 2 visible, when I no longer need it, I make it invisible again. When I no longer need the reference object I delete it from the working file.

I maintain my reference objects in a "refobj.blend" library file, importing them as needed, though a couple of items, like a center mark, are part of the default file.


Posted: Tue Aug 27, 2013 4:23 pm
by Eriku
Thank you, Brasshat!
Obviously I am not the only one that feels a need for the things I described. I do not quite understand your description, but you inspired me to build my own vector library. A bit clumsy, but better than nothing.

I will keep this thread open for a little while - maybe there is an "add-on" out there somewhere ...

Posted: Tue Aug 27, 2013 9:35 pm
by brasshat
I'll try again.

First, because empties in Blender can have the properties of size and rotation, they have axes so that the size and rotation of the empty can be determined. But they are really just place markers, and not really intended as measuring tools.

Now, when I had a need for measurements, I used specially created mesh objects to achieve the measurement. Suppose, for example, that I have and anchor point (point "A"), and that I want a second point (point "D") to be exactly 3.285 blender units from the anchor point, and I'm not fortunate enough that the location is on the X, Y, or Z axis relative to the anchor point.

To achieve this, I create a temporary object for measuring purposes. In this case, I might scale a cube to .025 x .025 x 3.285 blender units, and use one of the faces that is 3.285 long as a tool to move point "D" so that it is exactly 3.285 blender units from point "A", by locating one .25 long edge of the 3.285 face at point "A", and moving point "D" to the opposite .025 edge.

If I think I'm going to want this distance again in this project, I'll move it to an "attic" layer, so I can access it later. Otherwise, I'll delete the measuring cube when I'm done with it.

Maybe this is already what you have in your vector library, but as far as the capabilities you want to have with the empty, you can create a mesh object which has the properties you seek. Scale a cube object to the desired size, and extrude all six faces as the shaft, then apply the primitive of your choice (cone, uv sphere, cube, etc) to the end of each shaft. By assigning a vertex group to each shaft, and another vertex group to the the object at the end of each shaft, you will be able to scale the shafts and the ends independently. You can change the color by assigning a material to each shaft and end.


Posted: Wed Aug 28, 2013 12:31 pm
by Eriku
Thanks again - now I understand and I see the relevance of your method!
But I do not see that it covers my problem.
Let me too try again:

I want the possibility to graphically draw arrows and coordinate axes like those you can see in

and measure-lines and measure-arrows like those you can see in engineering drawings, see ... &FORM=IGRE

I have so far built coordinate axes and arrow shafts (as cylinders) and arrowheads (as cones) "by hand". The result looks acceptable, but it is a very clumsy, time consuming and tiresome method (and I still have not found out how to make the measure-lines). The result can be saved and reused by use of a library, but it is still very tedious to adapt to every specific case.
A built in facility for measure-lines and measure-arrows would expand the usability of Blender quite a lot, as I see it. I still belive that someone out there has an "add on" that fixes this ...
Note: "Design Aid" is quite another matter and that is not at all what I want - not at all!

Posted: Wed Aug 28, 2013 8:34 pm
by brasshat
OK. Seeing the illustrations to which you provide links, I find I misunderstood your intent. I thought you were looking for methods to gain precision in constructing objects in Blender, not looking to provide callouts and dimensions to objects.

I think what I'd do, if it were me, is to not use Blender for these elements you want to add. Instead what I'd do is to render the image of the object, save it, and then add the call outs and dimensions using another package. Unfortunately, I'm not in a position to make a recommendation as to which to use, because it is outside the area of my expertise.


Posted: Wed Aug 28, 2013 11:10 pm
by Eriku
OK, thanks again, Brasshat, for your interest and your efftort!
I will keep this thead open for some time ... just in case ...