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Problem using scale

Posted: Tue Feb 15, 2011 12:11 am
by TerraD
I use QCAD V2.2.2.0 - Demo

I was easily able to create an object consisting of 4 arcs and 1 line and mirror this to have my full object. All lines I talk about are in layer 0.

However I do need several versions of this object - all slightly different in size. So I decided to use the scale feature. This works well as long as I use 'Keep proportions'.

However as soon as I try to scale x by 0.9 and y by 1.1 only the 2 lines get scaled and copied.

Am I really so unlucky to stumble with my first drawing over a bug or am I just making a mistake? Any idea for a workaround? .DXF available upon request.

I made a block out of my object, but a block only has one scale factor. So this does not help as well.

Except for this problem QCAD would idealy suit my needs (at least if my final output can be processed by a laser cuting machine) without being too complicated

Posted: Tue Feb 15, 2011 7:23 am
by andrew
Arcs can only be scaled proportionally at this point.

Unproportional scaling would have to convert the arcs into ellipse arcs or line segments and is not supported for now.

Posted: Tue Feb 15, 2011 9:53 am
by TerraD
Thank you for this answer.

As a workaround I tried to scale an ellipse and a polyline unproportionally. Neither works. Think I'l try a polygon and remove the segments not needed. Any other workaround I could try?

Think I'll purchase QCAD anyway - not being able to scale unproportionally will just cause me a lot of additional construction work.

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Proposal: A message 'not all of the selected entities can be scaled unproportional' would be helpful - or maybe a short note in the documentation.

Posted: Tue Feb 15, 2011 2:44 pm
by andrew
TerraD wrote:I tried to scale an ellipse and a polyline unproportionally. Neither works.
Polylines are even more problematic. Arc segments in polylines would have to become ellipse segments. However, polylines cannot (by CAD definition) contain ellipse segments. Either the polyline would have to be exploded into lines and ellipses or the ellipse segments would have to be interpolated with smaller arc or line segments.

We might look into ways of dealing with this for future QCAD versions.

If you can provide more information about what you are doing and why unproportional scaling is important for you, that will be helpful for future QCAD development. Thanks.