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