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# Sketch symmetric constraint

## Sketch symmetric constraint

One of the improvements that should be made in sketch, is the symmetric constraint. Now it's only possible to create symmetrie by having an axis system, and applying the constraint only to vertices. it should be possible to do it to lines, arcs and circles.

1 Comment
14-Alexandrite

I've made a duplicate request, cause I haven't found this request yet. Solidworks does indeed apply symmetry to the endities, and not to the vertices, which is much better, since everytime we add a fillet, chamfer, or need to trim or extend a line, the simmetry constraints of the vertices get deleted. If we want to keep the simmetry, we have to use constrction geometry to try to maintaint the symmetry that existed previous to the trimming or extending odf the lines.

It should not be difficult to constraint the symmetry between entities. In the case of a line, what needs to be constrained is the angle, and a distance from an origin (of a point, or of a line). The endpoints should be free to be moved, or edited as necessary. In the case of the circles, besides constraining the center to be a mirror of the original one, the diameter should also be constrained to be equal. In the case of the arcs, it's the same, but do not constraint the endpoints, only the center and the radius.

We should also have the option to mirror around a "point" instead of a line only. This would guarantee that the mirrored entities would maintain a distance to the point, but would not constraint the angle of a line, for instance. This would allow to have centered rectangles wihtout the two crossed construction lines, since those construction lines get in the way when we want to add more geometry, for instance, we try to sketch something and there are equal dimensions, or paralell constrains added to any of those two crossed construction lines. It does not make sense, since the crossed construction lines should be used only to define the center of the rectangle, and nothing else. Mirroring geometry around a point would allow to remove those annyoing construction lines. In the case of the Centered rectangle, or any other polygon of the pallette, the system would draw a construction centepoint and the four lines with equal distance from each line to the center point. Two lines of the rectangle that are mirrored would behave like if there was an invisible circle and they both with be tangent to saaid invisible circle. We don't need the construction circle for nothing, it's the task of the solver to maintain the distance of each line to the center construction point. The other two lines of the rectangle, would similarly be tangent to another invisible construction circle, and the radius of this two circles is the distance that the solver would constrain, and the diameter of said two circles would define the width and length of the centered rectangle, with an additional constraint in the case of a rectangle to constraint two sets of paralell lines to be perpendicular to each other. Deleting that constraint, would give as a parallelogram. This would be much more useful than the current Centered rectangle, where in most cases we need to add fillets or chamfer, or add other lines that need to intersect part of the rectangle. And it would be much easier to rotate the geometry around the center point.