[solved] taking points at intervals from a line

fredo6

In general, interpolating points should be done with Geom.linear_combination
in your case, to create nb intermediate segments ( so nb+1 points, including first and last one)


def intermediate_points(pt1, pt2, nb)
   lpt = []
   for i in 0..nb
      ratio = 1.0 * i / nb
      lpt.push Geom.linear_combination(1 - ratio, pt1, ratio, pt2)
   end
   lpt
end

which you can write in a single line as well


(0..nb).to_a.collect { |i| r = 1.0 * i /nb ; Geom.linear_combination(1-r, pt1, r, pt2) }

Fredo

Dan Rathbun

@kyyu said:

You don't want to use a line. A line would have infinite length. Anyways, it's just seen as an array ( type "edge.line.class"). So the length of that array is always 2 elements in that array, which defines a line.

Yes. I am sorry Korbin, meant to use the second element from the line method (got rushed.)

I should have written:
vec = edge.line[1] not vec = edge.line

Also within a method, you dont need to use a global variable. Pass a reference to the line into the method as an argument. The argument name becomes a local reference (var) inside the method. (Do not get in the habit of using global vars. Its poor and lazy programming.)

<span class="syntaxdefault">def draw_vision_field</span><span class="syntaxkeyword">(</span><span class="syntaxdefault"> edge </span><span class="syntaxkeyword">)<br /></span><span class="syntaxdefault">  ents </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> Sketchup</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">active_model</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">active_entities<br />  vision_field </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">[</span><span class="syntaxstring">"test1"</span><span class="syntaxkeyword">,</span><span class="syntaxdefault"> </span><span class="syntaxstring">"test2"</span><span class="syntaxkeyword">,</span><span class="syntaxdefault"> </span><span class="syntaxstring">"test3"</span><span class="syntaxkeyword">,</span><span class="syntaxdefault"> </span><span class="syntaxstring">"test4"</span><span class="syntaxkeyword">,</span><span class="syntaxdefault"> </span><span class="syntaxstring">"test5"</span><span class="syntaxkeyword">]<br /></span><span class="syntaxdefault">  pt </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> edge</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">start</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">position<br />  puts pt<br />  vec </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> edge</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">line</span><span class="syntaxkeyword">[</span><span class="syntaxdefault">1</span><span class="syntaxkeyword">]</span><span class="syntaxdefault">       </span><span class="syntaxcomment"># fixed this <br /></span><span class="syntaxdefault">  vec</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">length </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> edge</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">length </span><span class="syntaxcomment"># added this<br /></span><span class="syntaxdefault">  puts vec<br />  num </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> vision_field</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">size </span><span class="syntaxkeyword">-</span><span class="syntaxdefault"> 1<br />  puts num<br />  seg </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> vec</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">length </span><span class="syntaxkeyword">/</span><span class="syntaxdefault"> num<br />  puts seg<br />  vec</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">length </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> seg<br />  vision_field</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">each_with_index </span><span class="syntaxkeyword">{|</span><span class="syntaxdefault">e</span><span class="syntaxkeyword">,</span><span class="syntaxdefault">i</span><span class="syntaxkeyword">|<br /></span><span class="syntaxdefault">    pt</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">offset</span><span class="syntaxkeyword">!(</span><span class="syntaxdefault">vec</span><span class="syntaxkeyword">)</span><span class="syntaxdefault"> if i </span><span class="syntaxkeyword">></span><span class="syntaxdefault"> 0<br />    ents</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">add_text</span><span class="syntaxkeyword">(</span><span class="syntaxdefault"> vision_field</span><span class="syntaxkeyword">[</span><span class="syntaxdefault">i</span><span class="syntaxkeyword">],</span><span class="syntaxdefault"> pt </span><span class="syntaxkeyword">)<br /></span><span class="syntaxdefault">  </span><span class="syntaxkeyword">}</span><span class="syntaxdefault"> <br />end<br /></span>

EDIT: edge.line[1] returns a unit vector, so we must add a statement to make vec the length of edge.

Dan Rathbun

@kdasilva said:

how can I get 10 Point3d's evenly spread out along this line that I can use as anchors for my text....

Divide the line by 9

<span class="syntaxdefault">arr</span><span class="syntaxkeyword">=[]<br /></span><span class="syntaxcomment"># load array with the txt values in order<br /></span><span class="syntaxdefault">pt  </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> edge</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">start</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">position<br />vec </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> edge</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">line</span><span class="syntaxkeyword">[</span><span class="syntaxdefault">1</span><span class="syntaxkeyword">]<br /></span><span class="syntaxdefault">vec</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">length </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> edge</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">length <br />num </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> dict</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">size</span><span class="syntaxkeyword">-</span><span class="syntaxdefault">1<br />seg </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> vec</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">length </span><span class="syntaxkeyword">/</span><span class="syntaxdefault"> num<br />vec</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">length </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> seg<br />arr</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">each_with_index </span><span class="syntaxkeyword">{|</span><span class="syntaxdefault">e</span><span class="syntaxkeyword">,</span><span class="syntaxdefault">i</span><span class="syntaxkeyword">|<br /></span><span class="syntaxdefault">  pt</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">offset</span><span class="syntaxkeyword">!(</span><span class="syntaxdefault">vec</span><span class="syntaxkeyword">)</span><span class="syntaxdefault"> if i</span><span class="syntaxkeyword">></span><span class="syntaxdefault">0<br />  entities</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">add_text</span><span class="syntaxkeyword">(</span><span class="syntaxdefault"> arr</span><span class="syntaxkeyword">[</span><span class="syntaxdefault">i</span><span class="syntaxkeyword">],</span><span class="syntaxdefault"> pt </span><span class="syntaxkeyword">)<br />}</span><span class="syntaxdefault"> </span>

EDIT: vec = edge.line[1] was vec = edge.line
Added: vec.length = edge.length as edge.line[1] returns a unit vector.

Dan Rathbun

@kyyu said:

You want to use the vector from the edge:

pt1 = edge.start.position
> pt2 = edge.end.position
> vec = Geom;;Vector3d.new [(pt2.x-pt1.x), (pt2.y-pt1.y), (pt2.z-pt1.z)]
> edge_length = vec.length

This is what I intended, but left off the index to the 2nd element.
edge.line[1] returns the unit vector for the edge, so:

vec = edge.line[1] vec.length = edge.length

kdasilva

Wow, thanks for all the help, and that fixed it up no problem.

Dan - I also got rid of all of the global variables...in some cases I used class variables I hope thats not bad coding...changes to a variable in one method needed to be consistent in other methods for some parts in the tool

(your all definitely getting a thank you foot note in my thesis!)

Cheers,
Korbin

Dan Rathbun

@kdasilva said:

also... where does the method each_with_index come from?

The method each_with_index() comes from the special mixin-module Enumerable, which is mixed into many other classes like String, Hash and Array.

On the Docs page for each class, it lists what other modules are "mixed-in" using the include() method, so therefore the caption Included.

And for Sketchup use the v 1.8.6 docs:
Core: http://www.ruby-doc.org/core-1.8.6/index.html

The Keywords apply to all branches and versions.
Keywords: http://www.ruby-doc.org/docs/keywords/1.9/

Dan Rathbun

@kdasilva said:

...in some cases I used class variables I hope thats not bad coding...changes to a variable in one method needed to be consistent in other methods for some parts in the tool

No that's proper programing.. (and what I do,) if the tool instance is a singleton instance (the only instance of the tool class that will be instantiated, which is usually the case,) ... then using class variables is fine.

If it's an instance of a class that will have more than one instance "live" at a time, then instance variables (beginning with only 1 @,) would be what you want to use. (That way each instance has it's own set of the variables.)

You can also use class constants (is place of global constants,) and local variables (in place of global variables.)

bilianb

@tig said:

pt=p.offset(vec, step)

Some help about the second argument \in API there is only one - vector\

Thanks

Dan Rathbun

@bilianb said:

@tig said:

pt=p.offset(vec, step)

Some help about the second argument \in API there is only one - vector\

Take another look, at offset() not offset!()

Point3d.offset

TIG

point.offset() returns a new point from 'point', offset as specified BUT
point.offset**!**() offsets the original 'point', as specified.

kyyu

Ah, thanks for all the tips, guys! The line[1] vector will be useful, as long you are after the forward edge direction. I tried to use it yesterday, but couldn't because the polyline direction did matter in my case. And the second argument in .offset(). I didn't realize there was a second argument and was scaling my vector, instead. Actually, I only recently realized you could scale a vector by vector.length= and had been doing it a harder way, before.

-Kwok