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jericsynrgy

Workflow: find a halfway point/nattering

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(R17)  This might be a bit of noobish nattering, but it'll help me, so maybe it'll help somebody else too: this brought up some simple stuff I should know how to do and so I'm asking here, hoping my approach is just not wrong-headed from the start:

 

For practice I'm modeling a turntable, and I have one symmetric bit I'm struggling with, it's a chunk of the tonearm gimble.  In my "design" it's about 60% of a thickish ring that has a crosspiece underneath that connects to the vertical pivot post of the tonearm.  The whole thing will be Sub'd to smooth it out.

In my first attempt I selected polys on the downward facing edge of the ring and extruded them, attempting to keep everything symmetrical.  (I'm not a fan of the symmetry OBJECT, being more used to a modeler with a symmetry MODE), than used Bridge to connect the two.  This didn't work well, and I could continue to natter but I'm simply backtracking and would like to restart, and the minor task that would make this easy peasy would be the ability to find the mid-point of the object, delete half of it, do the extrusion, and mirror it over.

Attached will be a picture:  how do I find the exact half-way point?  Can I make a bounding box, slice that in half, and use one-half to Boolean away the half I don't need of workpiece?

Thanks!
 

Gimble.jpg

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You could use the HUD. If you have turned on selected points, edges and polys you could use path select to select the edges along one side of the form, noting the total. Then just ctrl marquee deselect what looks like half, and see if the HUD reports half the number you noted earlier. But faster to just start again with a new cylinder / disc, which will arrive perfectly aligned to world center and you can use the slice options within them to adjust the slicing numerically...

 

Personally I'd get symmetry involved from the word go, but you can still use that in conjunction with slice to make sure you get a slice that happens evenly across an axis.

 

1139391999_Symmetryslice.thumb.gif.7c20059aeab7cef30a90ef313039b463.gif

 

CBR

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  • Thank you.  With such a very simple object, starting over is very viable strategy, but I'd also like to know- academically - how to determine the mid-point of arbitrary, possibly complex and/or organic mesh.

    FWIW, I haven't found a script that will, for example, generate a bounding box around arbitrary meshes.  For instance, in my stupidity, I didn't adjust the torus such that a division fell in a logical, useful place.

    In the GIF you posted, is that a LATHE occurring with

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    16 hours ago, jericsynrgy said:

    In the GIF you posted, is that a LATHE occurring with

     

    No, that's just a disc primitive (under symmetry) in which I am playing with the slice end parameter.

     

    16 hours ago, jericsynrgy said:

    but I'd also like to know- academically - how to determine the mid-point of arbitrary, possibly complex and/or organic mesh.

     

    If we're just talking about a single edge we can just use Mid Point Snap to instantly find the middle of it, but with whole organic meshes it's a slightly more oblique process..

     

    But let's think about this - the Coordinates Manager is very useful here in that it shows you scale dimensions based on the BOUNDING BOX around a mesh (you can even see those bounding boxes by setting display mode to Box), and the Object Axis of diligently created models should be exactly in the center of any object you create. And because you can also snap to the Axis, then that is often the fastest way of finding the middle of something - there is rarely a need to do it numerically. 

    But if we do need to know exact figures, then the Scale properties of the Coordinates Manager will tell you, and the half way point along any particular axis will be half the value displayed there (provided the CM is in Object Mode). That works really well UNLESS the polys in the object have become rotated off-axis, in which case the CM cannot know this, and its reports remain based on what the Object Axis is doing, so you need to be aware of that before relying on that method.

     

    Lastly, have  a look at the Measure and Construction Tool - this is not very intuitive, but once you've watched a Youtube video or 2 and understood the way it works it can be used (in conjunction with snapping) to accurately measure and set distances irrespective of poly or model rotation. However I would say in terms of practical day-to-day use you should almost never have to turn to this if your axes are just set correctly in your model !

     

    CBR

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    My eyeball assumed this (see pic) being your mid-point since it appears to be the edge-loop most aligned to the world axis. To double-check, all I did was count how many subdivisions you have in the arc, which is 48, then counted out 24 edge-loops from one side and my assumption was confirmed. Took less than 30 seconds.

     

    However, with this manual method there comes a few more steps needed in order to ensure that everything is aligned properly for symmetry.

    • First, delete the points that fall outside of the 24th loop.
    • Next, make sure the points where symmetry will occur are aligned to world:
      Select those points, look at the Size readout of the appropriate axis under the Coordinate Manager and zero it out if necessary. 
    • Set the object axis to the appropriate point for symmetry:
      Press L for axis edit mode, turn snapping on, move the axis to snap to the desired edges/points, press L again to exit axis editing.
    • Now you can put it under Symmetry.

     

    This is a great way to learn your way around C4D and manipulating objects. But if you want the fastest, cleanest way, then do Cerbera's ring with slice under symmetry from the start.

     

    midpoint.jpg.1e357eb6253dec73815851dd8865ec8d.jpg

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  • Thanks for everybody's assistance.

    One thing: this mesh is just a sub assembly of a (much) larger mechanism, so I was constructing off-axis for a reason.

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