Cursor constraint typed entry does not work

Rhino Rhino for Windows
1

Hi
V5

http://docs.mcneel.com/rhino/5/help/en-us/user_interface/cursor_constraints.htm

Angle constraint

Locks the next point will be placed at a specified angle relative to the last point.

To constrain to an angle
4 Type an angle at the command prompt in the format <angle and press Enter.

The cursor moves along a line at the specified angle.

NO IT DOESNT. well not for me anyway.

I select line tool, click start point, then type <47.457 and hit enter, draw the line in a north west direction which appears at that sort of angle (as rhino 0 is north) yet measure it afterwards at it isnt !.

have I overlooked something ?

it also will draw two other lines near vert and near horiz neither of which are 47.457 on anything.
Angle constraint fail.3dm (31.0 KB)
Steve

2

that may help to understand :wink:

3

Rhino ANGLE Zero is actually “East”… It starts along the X axis and rotates CCW with positive angles (right handed mathematical coordinate system).

–Mitch

4

Nope- zero is East, as is pretty standard I think.

-Pascal

5

Hi, I guess my school protractor is to blame, it had 0 straight up and went round to 90 both CCW and CW.

I have never in my head had east as zero.

Macromdeia Freehand when entering constrain 47 drew a line north west 47 deg to vert or horiz, one of the two.

Just tried it but no degree measuring tool to establish hrz or vert. Gosh how did I manage with no angle measuring device ?

On an RAF compass 0 was straight up.

bandits angels 15 vector 045 was north east !

I have always thought of up as base point.

why when it is natural to do so was east chosen ?

is there an option for altering base to north. I see there is in another cad prog.

Steve

6

From Wikipedia:

In a two-dimensional Cartesian coordinate system, an angle is typically defined by its two sides, with its vertex at the origin. The initial side is on the positive x-axis, while the other side or terminal side is defined by the measure from the initial side in radians, degrees, or turns. With positive angles representing rotations toward the positive y-axis and negative angles representing rotations toward the negative y-axis. When Cartesian coordinates are represented by standard position, defined by the x-axis rightward and the y-axis upward, positive rotations are anticlockwise and negative rotations are clockwise.