Rotating a line

[Acorn]

I might understand why the # works. Pressing the hash key shows the grid, so if hash is something to do with the grid, then typing hash plus the degrees tells the program to rotate relative to the grid (whether it is showing or not). Well ..it's a theory.

Sorry nothing at all like that, it was just a Xara whimsy. It didn't exist before v16.3.

Acorn

[ss-kalm]

Nearly all CAD systems use horizontal (right) as 0 degrees and rotate anti (counter) clockwise from there, so 90 is straight up 180 is left and 270 is straight down.

A line to indicate one minute would be 84 degrees.

[handrawn]

thanks keith I thought it might be that, but I don't use CAD; animation is different I guess

[gwpriester]

@ Mart, it really pisses me off, a vertical line should have a rotation of 0 (or 180) not -90 !!!

I would think the angle of rotation would be the original orientation of the line.

This does come in handy when I do some of my blended lines and shapes to create a spiral fill. Even though the start and end shapes start as vertical, the angle gets slightly changed for the start and end shape. So I can Ctrl select each shape and change the orientation. Not that it makes one bit of difference.

[Acorn]

Shapes and Text come with a natural zero-degree alignment on creation such that if you hold down the Ctrl key you can ensure a snap to 0^o.
Enter a rotation angle greater than 0.113^o and Xara turns it into a graphic - @Xara - thanks for that - this needs sorting!

A box has a start node top-left.
A circle/ellipse, top-centre.
A QuickShape is top and furthest left.
Something created with the Shape tool has an obvious start node.

Xara then decided to follow the two-dimensional cartesian coordinate plane system (along the road and up the stairs - X-Y axes).
When the axes are drawn according to the mathematical custom, the numbering goes counter-clockwise starting from the upper right ("north-east") quadrant.
0^o is aligned to point from the Origin to the right , along the X-axis.
Xara then added a counter-clockwise arc beside its Angle of rotation box.

Instead of 0 - 360^o, Xara chose to represent angles as 0 - 180^o for the top two quadrants and -180 - 0^o for the bottom two.
This allows a vertical flip with the change of sign. 0 - 360^o still is acceptable input as are any angle over 360^o, they are just calculated as modulo 360.

A Line has to have its initial orientation included as without that all lines would degenerate to the horizontal when they were set to 0^o.

Acorn

File:Polar_graph_paper.svg