[solved] taking points at intervals from a line

kdasilva

Hello, I am trying to get my head around how I can collect 3DPoints from a edge my users enter for a tool

essentially, the user draws a line on that line I want to display text at equal intervals along it. The text is not constant, it is taken from an attribute dictionary.

What I am hung up on is splitting my edge. I am trying to use the .split method based on a fraction created by the number of attributes in the dictionary, however my math is failing me in the sense that once I do the first split, I cant seen to get another split evenly placed down the line. Is there an easier way to do this?

For example:

lets say the user creates a line from [0,0,0] to [100,100,0] and there are 10 attributes

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

Any help would be greatly appreciated!

Cheers
Korbin

Cleverbeans

To get the points you'll want the vector from Edge.start to Edge.end, then scale it by your factor and transform the start point by the scaled down vector to get you first point, then repeat on that new point until you're done. Here is some code.


def even_split(edge,splits)
	point = edge.start.position 
	vector = point.vector_to(edge.end.position)
	scale = Geom;;Transformation.scaling(1.0/splits)
	vector.transform!(scale)
	for i in 1...splits
		point.transform!(vector)
		edge = edge.split(point)
	end 
end

TIG

Let's call them p0 and p1
The distance between them...
dis=p0.distance(p1)
Let's assume we want to find a set of points at 1/n steps
step=dis/n
Then process and increment
vec=p0.vector_to(p1) pts=[p0] p=p0.clone (n-1).times{ pt=p.offset(vec, step) pts << pt p=pt.clone } pts << p1
You now have an array 'pts' of all points including the start and end ones and all intermediate ones as required...

kdasilva

@dan rathbun said:

@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<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>

I am trying my hardest to get this to work, unfortunately I have been unsuccessful thus far.....i put in:

def draw_vision_field
  vision_field = ["test1", "test2", "test3", "test4", "test5"]
  pt = $line.start.position
  puts pt
  vec = $line.line
  puts vec
  num = vision_field.size - 1
  puts num
  seg = vec.length / num
  puts seg
  vec.length = seg
  vision_field.each_with_index {|e,i|
    pt.offset!(vec) if i > 0
    $ents.add_text( vision_field[i], pt )
  } 
end

I just put a test array to print for now. I added the puts in order to try and debug, I am getting this error message regarding the length= function on a vector...also the last number before the word error (the vec.length /num ), weirdly enough is always 0, i removed the /num and it always prints as 2, no matter how long the line is i make)


(-350507.397831", 21906.712364", 0")
(-350507.397831", 21906.712364", 0")
(0.131501105216966, 0.991316023943281, 0.0)
4
0
Error; #<NoMethodError; undefined method `length=' for [Point3d(-350507, 21906.7, 0), Vector3d(0.131501, 0.991316, 0)];Array>
(eval);70;in `draw_vision_field'
(eval);55;in `draw_the_line'
(eval);28;in `onLButtonDown'
(eval);73

also... where does the method each_with_index come from? I can't find it in the sketchup api, and I could only find each_index in the ruby-doc http://www.ruby-doc.org/core/classes/Array.html#M000232

thanks for the help

korbin

kyyu

@kdasilva said:

<snip>
i removed the /num and it always prints as 2, no matter how long the line is i make)
<snip>

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.

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

@kdasilva said:

<snip>
also... where does the method each_with_index come from? I can't find it in the sketchup api, and I could only find each_index in the ruby-doc http://www.ruby-doc.org/core/classes/Array.html#M000232

thanks for the help

korbin

The sketchup api just documents, extra ruby Modules/Classes/methods for sketchup. It doesn't document the entire ruby language.

-Kwok

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