Help adding arc in ruby script

[ktkoh]

I am currently working on a mortise tool script based on the dado tool of Woodwrk.rb and it is working fine for square end mortise but I also want to add the capability of round mortise that is made with a router.

This is the final section of the script that draws the mortise:

 po1=pt1.transform(backt) #Typical results (3.75,-0.5,0)
 po4=pt4.transform(backt) #Typical results (3.75,-0.25,0) 
 po2=pt2.transform(backt) #Typical results (0.25,-0.5,0)
 po3=pt3.transform(backt) #Typical results (0.25,-0.25,0)
 codef=@entity.definition
 cface=codef.entities.add_face po1,po2,po3,po4

 h=-1*@@depth	   
 cface.pushpull h
 Sketchup.active_model.commit_operation

What I need to do is add a curve (half circle) that connects p1 to p4 and p2 to p3
From the SU I see that this is the type of code that is needed and I know the centerpoints
radius but am not sure of the start and end vectors etc.

# Create a circle perpendicular to the normal or Z axis
vector = Geom;;Vector3d.new 0,0,1
vector2 = Geom;;Vector3d.new 1,0,0
vector3 = vector.normalize!
model = Sketchup.active_model
entities = model.active_entities
arccurve = entities.add_arc centerpoint, vector2, vector3, 10, 15, 35
UI.messagebox arccurve 

Your help would be appreciated
Keith

[TIG]

The start/end vectors are those from the centerpoint to the start/end points of the arc.
You have those points, so vec_start=start_point-centerpoint and vec_end=end_point-centerpoint will give these vectors.
You need to know which end is which so that the required part of the arc gets drawn...

[ktkoh]

TIG if I am reading your post correctly I define the vectors as shown?

vec_start=po1-centerpoint
vec_end=po4-centerpoint

Second question will the following statement pick the face that includes the radius on the ends between point1 and point4?

cface=codef.entities.add_face po1,po2,po3,po4

Thanks for your help
Keith

[thomthom]

@ktkoh said:

Second question will the following statement pick the face that includes the radius on the ends between point1 and point4?

cface=codef.entities.add_face po1,po2,po3,po4

That won't pick a face. It will create a new one. But it will return the newly created face.

[tomot]

arcs are not easy! ....here are some code sippits from a a ruby of mine, I hope this helps!

    x=0
    y=0
    z=0
    pi = 3.141592653589793  # 180 degree angle = pi radians
    vecz = Geom;;Vector3d.new(0, 0, 1)
    vecy = Geom;;Vector3d.new(0, 1, 0)     
    vecx = Geom;;Vector3d.new(1, 0, 0) 

# the 4 quadrants of a circle; are
#
#  pi, pi/2 | 0,pi/2
#  ---------+--------
# -pi/2,-pi | -pi/2,0
#
# the following, is an example using an arc statement incorporating the above definitions
# this arc is 90 degress, and lies in the 2nd quadrant
#
model.entities.add_arc([x+@dist, y+@dist, z], vecx, vecz, @d/2, 0, pi/2, @s)
#

[TIG]

It's often forgotten that you can specify angles in Ruby Sketchup in degrees directly, thus angle=180.degrees - no need to muddle on with PI and radians !

[thomthom]

tomot:
No need to define pi yourself as a variable. (first of all it'd make more sense to defined it as a constant)
But you have it already define in the math module: Math::PI

And you don't have to calculate the radian values yourself. The Numeric class has .degrees and .radians to do that for you. http://code.google.com/apis/sketchup/docs/ourdoc/numeric.html

model.entities.add_arc([x+@dist, y+@dist, z], vecx, vecz, @d/2, 0, 90.degrees, @s)

(whoop! TIG beat me to it... Except the PI part.)

[artmusicstudio]

hi,
is it also possible to draw a 3-point-arc in ruby? without defining a center?

i want to ad an arc along an edge, so the points would be (when edge is in y-direction):

arc_1 = 0,0,0
arc_2 = 0,y,0
arc_3 = x,y/2,0

is there a way?

thanx stan

[TIG]

@artmusicstudio said:

hi,
is it also possible to draw a 3-point-arc in ruby? without defining a center?

i want to ad an arc along an edge, so the points would be (when edge is in y-direction):

arc_1 = 0,0,0
arc_2 = 0,y,0
arc_3 = x,y/2,0

is there a way?

thanx stan
Yes of course, but it needs some trigonometry...
Find my 'Arc_By...' tools in the PluginsStore and see the RB inside the RBZ archive.
The RB include algorithms for making arcs in many ways...

[artmusicstudio]

hi tig, ok,
let's play with some formulas
thanx stan