Would be easy enough using an openGL overlay, like index visualiser does (by Crouch). The real interesting part is to measure between snappable elements on different objects, and to keep track of them so that you can have measurements that display face-on according to the 3dview orientation (if you want to make the measurement graphics renderable).
While I prefer AutoCAD for architectural stuff, and recently even Draftsight for 2D engineering stuff, it is becoming tempting to add a resemblance of this functionality to Blender myself. I have a few thoughts on the matter and some questions:
- be able to measure between 2 empties (linear)
- be able to measure between 3 empties (arc, angle ) …slightly tricky
- add anti-aliased openGL rendered dimensions as a render layer (ie, not geometry… it doesn’t look good).
- choose imperial / metric
- modify the (text / line / marker) sizes at runtime
- set precision
the first milestone would be
- [ ] can I render openGL/bgl output to a render layer, that scales and matches geometry with render dimensions