Sketcher CreateEllipseBy3Points/es

Descripción
Esta herramienta dibuja una elipse eligiendo tres puntos : (1) la periapsis (primer cruce del diámetro mayor con la elipse), (2) la apoapsis (segundo cruce del diámetro mayor con la elipse), (3) un punto en un lado del diámetro mayor (a) que define el radio menor (b). (c) es el centro resultante y (f) son los puntos focales.

Al iniciar la herramienta, el puntero del ratón cambia a una cruz blanca con un icono de elipse roja.



Utilización

 * Press the button.
 * First click in 3D view sets a point that defines the crossing of the major diameter with the ellipse (periapsis). Second click in 3D view sets a point that defines the crossing of the major diameter with the ellipse opposite to the center point (apoapsis). Third click sets a point on the ellipsis defining the minor radius.


 * After the third click, the ellipse is created, together with a set of construction geometry aligned to it (major diameter, minor diameter, two foci). The construction geometry can be manually deleted if not needed, and recreated later. See Internal Alignment Constraint and Sketcher Show Hide Internal Geometry.
 * Pressing or clicking the right mouse button cancels the function.

Peculiarities

 * Major and minor axes of ellipses are strict and cannot be swapped by resizing the ellipse. This is a consequence of the solver parametrization used (center (x,y), focus1 (x,y) and minor radius length (b)) and the same strict behavior of OpenCascade. The ellipse must be rotated to swap the axes.
 * Ellipse can function as a circle when its major and minor diameter lines are deleted, and one of the foci is constrained to coincide with the center. But radius constraint won't work on such a circle.
 * Moving the ellipse by edge is the same as moving ellipse's center.