# Modeling objects using polar coordinates rather than cartesian coordinates?

To make several vertices co-planar, the usual way is to use Scale = 0 along some convenient axis, but sometimes there is no convenient axis, e.g in this case were I placed the vertices using polar coordinates:

How to make the selected vertices co-planar again after they have been a bit disturbed. The target plane contains the global Y axis and the average angular position of the selected set.

I understand I could rotate the vertices around Y, so that they are roughly aligned with Z, then use Scale X = 0. That's what I do, but I'm looking now for a more accurate and less fastidious method.

In a more general way, is there a method (I assume this would be a addon) to facilitate work when dealing with object constructed by angle-distance rather than distance-distance. For example a method which would allow to move the selected vertices radially by the same specific distance (e.g. move each vertex away by 2 cm from the center of the object) while keeping their angular position unchanged?

• Totally confused by this question.The picture suggests to me they are on a plane Y=0 (or some constant) I know what polar coordinates are, not sure how you placed vertices using them. If it was done using a script for example you could relocate them. using data. I have a spherical coordinates addon somewhere. In a script with the origin at center , if you wish to move a vert dl radially, v.co = (v.co.length + dl) * v.co.normalized() for each selected vertex. – batFINGER Jan 13 at 12:30
• @batFINGER: This is a ring-like shape turned around Y. It was constructed manually by a flat closed set of segments in the say X-Y plane. A Screw modifier was added to give some angular depth around Y (e.g. 10°) and an Array modifier (using an empty to set a rotation step of 10°). Both modifiers where applied so that the object can be altered for the non symmetrical elements. The changes are mostly dealing with adjusting the angular position (e.g. forcing altered elements to be on the same radial plane), or the distance to the center. – mins Jan 13 at 13:26
• Something like i.stack.imgur.com/Jcd7p.gif – batFINGER Jan 13 at 15:24
• @batFINGER. Yes (if the move distance is the same whatever the original distance from the center -- else it would be equivalent to a Scale with the pivot point at the center, the operation I actually use for the moment). If I have an initial python code, I think I could later add several functions, like aligning vertices along a radius. – mins Jan 13 at 17:13
• Uses code as shown in first comment. Each vert is dl further from the origin along its radial. eg moving 0.1 a vector that was length 1 is now 1.1 and 10 to 10.1, hence not the equivalent of scale. – batFINGER Jan 13 at 17:59