Drawing A Polyline with AutoLISP 6

The DPLIP Function


This function is long. And it is also a little bit complicated. But you will understand the function. I hope.


Here is the function:


(defun-dplip-(et-sp-ss-/-e1-el-ip-p1-p2-p3-p4)
---(setq-el-(entget-et)
---------p1-(cdr-(assoc-10-el))
---------p2-(cdr-(assoc-11-el))
---)
---(setq-e1-(ssname-ss-0))
---(if-(equal-et-e1)
------(setq-e1-(ssname-ss-1))
---)
---(setq-el-(entget-e1)
---------p3-(cdr-(assoc-10-el))
---------p4-(cdr-(assoc-11-el))
---)
---(if-(or-(=-(angle-p1-p2)(angle-p1-p3))
-----------(=-(angle-p1-p2)-(angle-p2-p3))
-------)
------(setq-ip-p3)
------(setq-ip-p4)
---)
---(if-(=-(+-(distance-p1-sp)
-------------(distance-sp-ip)
----------)
----------(distance-p1-ip)
-------)
------(command-"pline"-p1
-----------------------"w"
-----------------------2.5
-----------------------2.5
-----------------------ip
-----------------------""
------)
------(command-"pline"-p2
-----------------------"w"
-----------------------2.5
-----------------------2.5
-----------------------ip
-----------------------""
------)
---)---
)


We give an entity to the function together with the selection point and the selection set that was found in the previous function.


Finding Two Points Of The Line


We want to find the two points of the entity. The entity is a line. This is how we find the two points of trhe line.


(setq-el-(entget-et)
p1-(cdr-(assoc-10-el))
p2-(cdr-(assoc-11-el))
)


Finding The Other Line


Another line is coming to the line that we have selected. We want to know what that line is. It is in the selection set.


There are two entities or two lines in the selection set. We take the first entity of the selection set.


We see if it is the same as the entity that was given to the function. If it is, then we take the second entity of the selection set.


Here are the programming lines:


(setq-e1-(ssname-ss-0))
(if-(equal-et-e1)
(setq-e1-(ssname-ss-1))
)


Now we have the line that is drawn against the line that has been selected. We find the points of that line. Here is how.


(setq-el-(entget-e1)
p3-(cdr-(assoc-10-el))
p4-(cdr-(assoc-11-el))
)


The Point On The Selected Line


Now we need to find what point is on the line that has been selected. We check the angles. Here is how it is done.


(if (or (= (angle p1 p2)(angle p1 p3))
(= (angle p1 p2)(angle p2 p3))
)
(setq ip p3)
(setq ip p4)
)


Now we know the two points of the line that has been selected. And we know the point of the other line that is on the line.


How The Polyline Is To Be Drawn


Now we must figure out how a polyline is to be drawn. We must figure out between what points the polyline must be drawn.


We know. The polyline is drawn to the point of the other line that is on the selected line. But from where is it drawn?


Is it drawn from point P1 or is it drawn from point P2. The points P1 and P2 are from the selected line.


It is quite simple to find out between what points the polyline must be drawn. We look at the distances.


There is the distance between P1 and the selection point and the distance between the selection point and the point of the other line.


If the total of those distances are the same as the distance between P1 and the point of the other line, then we know.


Then the polyline is drawn from point P1 to the point of the other line. Otehrwise it comes from point P2.


Here are the lines of the AutoLISP program.


(if (= (+ (distance p1 sp)
(distance sp ip)
)
(distance p1 ip)
)
(command "pline" p1
"w"
2.5
2.5
ip
""
)
(command "pline" p2
"w"
2.5
2.5
ip
""
)
)


Next Post


In the next post I'm going to talk about the main part of the AutoLISP program. And then I'm done talking about this AutoLISP program.


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Free AutoLISP Course


Sorry. This offer is only for my readers from Malaysia. I want to give an AutoLISP course to them. Free of charge.


I have more than 900 readers. The majority of them is from the USA. More than 500. But I also have readers from Malaysia. About 120.


I don't know what my readers from Malaysia are doing. Are they with an engineering firm or architecture? Or just interested in AutoLISP?


I offer them a free AutoLISP course. It works like this. You let me know if interested and I'll come to your place.


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