Dynamic slope for ground model

[AlexKDJ24]

Hello there, I am new to creating dynamic blocks and although I have been able to make simple ones, I cannot find a solution to this issue.

Want I want to do is create dynamic block that reads in two Z co-ordinates, measures the distances between them and returns a Gradient 1:xxx with a slope arrow. I can see how you read in the X and Y but not Z and likewise I can create a block with movable grips in X and Y but it does not seem to function in Z. Is this possible? Please can someone help.

[AlexKDJ24]

Or even an Lisp routine would do, but I was trying to be clever 😃

[MMcCall402]

I put together a sample to show how it could be done.  I used a construction line, an attribute with a field formula with other fields, and a polar parameter with a couple stretch actions to move things around.  The attribute formula takes info from the construction line, its length, end Z and start Z.  When the block is used its grips pick up the elevation of the objects they snap to.

[j.palmeL29YX]

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@AlexKDJ24 wrote:

... dynamic block that reads in two Z co-ordinates, 

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? "read coordinates" ?

Where are the Z-coordinates coming from? Do you want to type the values anywhere or do you want to measure an existing object (or two points) or ... ?

How shall the result look? Can you show us an example?

[AlexKDJ24]

That is awesome! thanks very much and for the quick response!

[AlexKDJ24]

Thanks again, but on a closer look, this is not giving the correct answer, for instance in the example you sent, the distance between the two points is 94.37 with a rise of 5.0, which should return a gradient of ~1:19 but it does not. It was very close to what I was looking for, but inaccurate.

[AlexKDJ24]

Thanks for your response Jürgen,

Sorry I was vague, I am trying to measure between two existing entities on a ground model, so similar to the previous answer, I am looking for a block which essentially measures itself. Snap one grip to one end of the surface / area (an existing entity) and snap another grip to another existing entity and the block works out the gradient as a 1:xxx fall with a directional arrow aligned to the block.

[AlexKDJ24]

Mark,

Looking at it again, the problem appears to be coming back to the issue I was having before, that the grips do not appear to pick up changes in Z (elevation) so when you alter the grips on the block it changes the length as intended, but not the change in height (z) therefore does not calculate correctly.

[j.palmeL29YX]

Dynamic block are designed for use in 2D only. So I'm afraid there is no way to get what you want. 

But with a little LISP you can write a tool which askes you for the two points and places the slope text between the two points as shown above. The disadvantage: you can not dynamically drag the points. If you change the geometry, you must delete the slope text and run the LISP again. 

If you can life with that handling I can show you tomorrow an appropriate LISP example (or, if you are in hurry, you shoud ask in the LISP forum).  

[MMcCall402]

It appears like it just as Jürgen says, dynamic blocks are only 2D.   I didn't pay enough attention to the values I was getting.

If you were using Civil 3D this would be very easy.  A simple slope label on a line object, done.

I was toying around with a dimension to see if it was possible to put a field in the dimension text what could access the start and end z values of the dimension.  No luck.   I did notice that you could put in a field for those properties of an associated line and calculate its slope and the dimension would follow the line because it was an associated dimension.

[AlexKDJ24]

Jürgen and Mark,

Thank you very much for your help. I was coming to the conclusion that perhaps it was only 2d.

But Jürgen, I would be very grateful if you could assist with a Lisp routine, that would work just as well. I have looked at lisp routines before, and use a few (premade) ones regularly, but am no good at coding.

thanks

Alex

[j.palmeL29YX · Accepted solution]

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@AlexKDJ24 wrote:

I would be very grateful if you could assist with a Lisp routine, 

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Attached a first rough draft of a LISP (after loading the .lsp file start with SLOPE). 

Obviously you calculate the X in the slope 1:X with horizontal distance divided by the vertical distance of the both points. I'd do it reciprocal - vertical distance divided by the horizontal distance. But that's your choice. You only need to change the line 

slope_num (/ delta_xy delta_z) 

to

slope_num (/ delta_z delta_xy)

(and choose an appropriate number of decimals 

slope_str (rtos slope_num 2 0) 

change to 

slope_str (rtos slope_num 2 3). 

Of course you can (should) refine this draft to your needs. 

(defun c:slope (/)
  (setq	p1	  (getpoint "\nFirst point: ")
	p2	  (getpoint "\nSecond point: ")
	p2_	  (list (car p2) (cadr p2) (caddr p1))
	delta_z	  (- (caddr p2) (caddr p1))
	delta_xy  (distance p1 p2_)
	angle_xy  (angle p1 p2_)
	halfway	  (polar p1 angle_xy (/ delta_xy 2))
	slope_num (/ delta_xy delta_z)
	slope_str (rtos slope_num 2 0)
	slope_txt (strcat "1:" slope_str)
  )
  (command "text"
	   "_J"
	   "_BC"
	   halfway
	   3.5
	   (/ (* 180 angle_xy) PI)
	   slope_txt
  )
  (princ)
)