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Re: gEDA-user: Specification of Rotations for Auto Assembly





Bert Timmerman wrote:
The right hand rule says: if you spread your first 3 fingers (starting with thumb) orthogonal to each other, thumb = X, point = Y, middle = Z ( or if you hook your fingers to indicate a rotation that will move X into Y, spreaded thumb poins to Z+). This is the basis for all math definition on vector operations in 2D and 3D, it defines the mathematically positive sense of rotation (CCW from above). All mechanical CAD systems and robotics controls adhere to this.
I gave this explanation, why I don't like the CS. It's clear to me that changing it while simple in principle would make files not backwards compatible and is
error prone.
So to define a rotation consistent with production, the first thing one must do is set up a proper 3D coordinate system.


As long as the internal coordinate system of pcb is consistent within the
code base, and the proper coordinate system is used for the exporter for
each purpose, then why change and have the risk of implementing (new)
errors.

When it works, don't fix it.
Defining a proper 3D coorinate system is sufficient for export filters in conjunction with rotation.
It wasn't necessarily meant to change the internal CS of pcb.



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