Local/global coordinate systems

[periodic]

I have a thought about transformations. I have seen that it has been discussed before about transformations centers etc.

My idea is to extend the concept of a rotation center to actually be the objects local coordinate system. I would the like to be able to move rotate and transform that coordinate system, just like any other object. A simple button should let me modify either the object or its coordinate system.

This will give a number of benefits:

I when placing the origo of the object I say where I want the rotation to take place and also have the option to snap other objects to its origo.

Also rotating around origo can either cause the coordinate system to rotate with the object or the object is just rotated in the coordinate system.

Having a rotated coordinate system would allow me to drag an object along the coordinate system axises instead of along just the axises of a global coordinate system.

There should also be options to align the local coordinate system along other objects in the drawing, e.g. selecting two nodes and select the axis to align.

I guess there should still be options to transform an object around its bounding box center and so on.

I guess there could be an option to work with a modified global coordinate system as well. Like if I want to have all I draw rotated 45 degrees from the papers orientation.

There are probably a lot more things that can be done with this, so I am happy if other people will help out to fill in the holes.

I know this will in some ways raise the learning curve for some people. But on the other hand, the current system is just a subset of what could be done with local coordinate systems. So it could be an option to use inkscape in advanced or simple mode. But having worked with this type of modeling in 3D software I can tell that once mastered, it is a powerful tool and will make many things simpler.

Much of this functionality already exist in any descent 3D rendering software and I don't see the reason to not include it in a 2D drawing tool. After all it should be easier in 2D than in 3D.

At the moment I don't have time to draw some images of how I would like it to work. But if I get some response to this request I will sit down and draft a more complete suggestion.

[su_v (suv-lp)]

(Partially) related reports/feature requests (not an exhaustive list):
Bug #170347 “ability to set coordinate origin”
Bug #170498 “Rotate and Flip Canvas”
Bug #170674 “Select a new reference point for object coordinates (basepoint)”
Bug #171203 “Use viewBox to explicitly define a coordinate system”
Bug #171488 “User-defined coordinate system”
Bug #171826 “view/edit current transform decomposed into rotation/scale/.”
Bug #179309 “Add option to preserve scale/rotate/translate instead of converting to matrix()”
Bug #503014 “Provide Object Coordinate Support”
Bug #550916 “Precision Input Center”

Blueprint "Transformation anchors"
<https://blueprints.launchpad.net/inkscape/+spec/transformation-anchors>

Blurprint "Geometric & Tech Drawing"
<https://blueprints.launchpad.net/inkscape/+spec/tech-drawing>

Blueprint "User-definable Object-attached Guidelines and Points for Mutual Object Positioning and Aligning"
<https://blueprints.launchpad.net/inkscape/+spec/user-definable-object-attached-guidelines-and-points-for-mutual-object-positioning-and-aligning>

Inkscape Wiki: CAD
<http://wiki.inkscape.org/wiki/index.php/CAD>