Transformation.rotation help

s_k_e_t_c_h_y

Hi,
I can't get this to work quite right so I was hoping for some insight. The Transformation.rotation is a bit light on documentation in the API.

@unknownuser said:

Transformation.rotationSketchUp 6.0+
The rotation method is used to create a Transformation that does rotation about an axis.

The axis is defined by a point and a vector. The angle is given in radians.

Arguments:

point
A Point3d object.
vector
A Vector3d object.
angle
A numeric value, expressed in radians, that specifies the angle to rotate about the axis set by the second parameter.
Returns:

transformation
a new Transformation object

From what I understand the point will be in 3D, but the Vector has to only contain 1 Dimension (i.e. the axis you'll be rotating around such as [0,0,1] or [1,0,0]).

What I want to do is rotate to a vector in 3D, which is essentially 2 successive rotations around axes such as y then x. The problem is that the two rotations that equal my 3d vector's direction don't lead to a correct rotation, but if I do only one of the rotations each seems correct for its respective axis.

I have a feeling I may need to just enter my own transformation matrix, but I was hoping I could just do it with existing commands...thoughts?

To make it a bit clearer here is an image. I want to rotate and translate an object from a point (origin in this case) to the end of a vector. This requires a rotation in two planes and a translation...

You can do the rotations with one operation in SU so I'm presuming I'm just missing something...

Sketchy..

s_k_e_t_c_h_y

You can see how it is wrong....

Here is the code....


						p = Geom;;Point3d.new([0, 0, 0])    #Point of rotation	
						
						#Create a copy, but don't move it (it needs rotating first
						trans = Geom;;Transformation.translation([0,0,0])
						new_hub = @geodesic.entities.add_instance hub_def, trans
						
						#Create a vector pointing up the Z axis
						z_vec = Geom;;Vector3d.new [0, 0, 1]
						
						#Turn our target point into a vector
						cv = Geom;;Vector3d.new c[0], c[1], c[2]
						
						#Get the angle between the Z-axis and the vector
						angle = z_vec.angle_between cv
						
						#Create a rotation transform and rotate the object
						r1 = Geom;;Transformation.rotation(p, cv, angle)
						new_hub.transform!(r1)
						
						#Translate to final destination
						t = Geom;;Transformation.translation(c)
						new_hub.transform!(t)

renderiza

Hi,

The following example code aligns the object axis with line axis pretty close, its a little off but not by much...not sure why this happens.

Here is the code;

model = Sketchup.active_model
ents = model.active_entities
sel = model.selection

@rotx = 0
@roty = 0
@rotz = 0

#change to see diferent line rotations
edge = Sketchup.active_model.entities.add_line([0,0,0],[-400,700,200])

line = edge.line
lend = edge.end
lendp = lend.position

sel.each do |e|
    pi = Math.acos(-1)
    @rotx = Math;;acos(line[1].x)*(180/pi) #/
    @roty = Math;;acos(line[1].y)*(180/pi) #/
    @rotz = Math;;acos(line[1].z)*(180/pi) #/   
end

tobject = sel[0]


tr1 = Geom;;Transformation.rotation(ORIGIN, Y_AXIS, @rotz.degrees)
tr2 = Geom;;Transformation.rotation(ORIGIN, Z_AXIS, @rotx.degrees)
tr3 = Geom;;Transformation.new([lendp.x, lendp.y, lendp.z])

instance = ents.add_instance(tobject.definition, tr1)
instance = instance.transform!(tr2)
instance = instance.transform!(tr3)

Note: before running code you need to have a group selected.

fredo6

@s_k_e_t_c_h_y said:

To make it a bit clearer here is an image. I want to rotate and translate an object from a point (origin in this case) to the end of a vector. This requires a rotation in two planes and a translation...
[attachment=0:3fw9rw9b]rotation.png[/attachment:3fw9rw9b]

You can do the rotations with one operation in SU so I'm presuming I'm just missing something...

Sketchy..

I think you should try the Axis Transformation, which can do it in one go.
You have the Z direction (your vector), and you need to fix the X or Y direction in the plane normal to your vector (or let SU decide by simply using an axes system based on vec.axes.

Fredo

tt_su

What fredo said, Transformation.axes sounds like the method you want to use: http://www.sketchup.com/intl/en/developer/docs/ourdoc/transformation.php#axes