Creating Arcs

[honoluludesktop]

Anyone have problems with @entities.add_arc, and selection.add_arc ? I am using Acad's dxf definition of arc for starting, and ending angle, but am getting a circle, not an arc.

vector = Geom;;Vector3d.new 0,0,1  
@vector2 = Geom;;Vector3d.new 1,0,0  
@vector3 = vector.normalize! 
.
.
.
my_arc = @entities.add_arc [@entity[0],@entity[1],@entity[2]], @vector2, @vector3, @entity[3], @entity[4], @entity[5], 24

Am I too tired to see the obvious?-) Hanging it up, and going to bed.

[thomthom]

Check the data you are feeding the method.

[TIG]

There is only a entities.add_arc(...) method - there isn't one for 'selection'

[honoluludesktop]

Thanks tt, and oops about my own typo TIG. I meant to write status = entities.add_selection my_arc, where my_arc = @entities.add_arc [@entity[0],@entity[1],@entity[2]], @vector2, @vector3, @entity[3], @entity[4], @entity[5], 24.>_<

[honoluludesktop]

Finally got back to this, and checked data as suggested. I had to rotate the normalized z and x axis, and convert my data to radians. Too bad the API is not set up for beginners, or Architects:-) Now on to calculate the default number of line segments for arcs.

my_arc = @entities.add_arc [@entity[0]+@block_x,@entity[1]+@block_y,@entity[2]+@block_z], @vector2, @vector3, @entity[3], @entity[4]*(Math::PI/180), @entity[5]*(Math::PI/180), 24

[thomthom]

There are methods to convert between degrees and radians:
http://code.google.com/apis/sketchup/docs/ourdoc/numeric.html

From radians to degrees:
1.22.radians

From degrees to radians:
30.degrees

[honoluludesktop]

Well, I finally took the time to make this really work. Starting and finishing angles are measured in radians, measured counter clockwise from the +x axis. I needed to add 360 to the finishing angle.

When:
vector = Geom::Vector3d.new 0,0,1 @vector2 = Geom::Vector3d.new 1,0,0 @vector3 = vector.normalize!
The correct arc is drawn by:
my_arc = @entities.add_arc [@entity[0]+@block_x, @entity[1]+@block_y, @entity[2]+@block_z], @vector2, @vector3, @entity[3], (@entity[4]*Math::PI)/180, ((360+@entity[5])*Math::PI)/180

@block_? is the location of the block/group from the origin. When an entity, its value is 0.0, nothing.

Only problem now, is that the data from my Cad's DxfOut, and Acad's seems to be different. I have to check the spec. by their version numbers, but I can't believe they have changed that much.>_< But "Oh well", that's why I am writting this s*^&&y app.:-)

Addenda: I found this variable tags 210, 220, and 230 (extrusion direction) wherein my Cad's DxfOut is [0,0,-1], and the default Acad's is [0,0,1]. What's an extrusion direction?

Addenda: z=-1 in [x,y,z] seems to mean that the arc is mirrored around the world view origin. It appears that when z=1 in [x,y,z], the arc is mirrored on the y axis, and set by (see the green (-)) below:
my_arc = @entities.add_arc [%(#008000)[-]@entity[0]+@block_x, @entity[1]+@block_y, @entity[2]+@block_z], @vector2, @vector3, @entity[3], (@entity[4]*Math::PI)/180, ((360+@entity[5])*Math::PI)/180