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Posted (edited)

Regards,

 

Does anyone know how to calculate points O1, O2, O3, O4 knowing coordinates P1, P2, P3, P4 and distances d1 , d2 , d3 ?

 

Offset.jpg

It's actually a section of pipe with different diameters.

 

Thanks in advance

Edited by Costinbos77
Posted

Just keep in mind that you will have to calculate the offset by moving the points perpendicular on original object.

 

Referring to the sketch below: if you know the points P1a and P2a, then you can calculate the angle of the line - see ANGLE function; next calculate P1b, respectively P2b using POLAR function, the offset distance and the calculated angle to which you will add 90 degrees. Do the same for the other side (take care of the side of offset).

 

offset_cost.gif

 

To get the intersection point for the two offsets, check INTERS function and use the four points you just calculated.

 

PS. Please check that on your sketch the point O1 cannot be obtained dirrectly by offset, it will require some extra constrains.

Posted

Thanks for the reply.

 

I'm particularly interested to O2 ,

because it is between two different distances: d1 and d2.

Posted

After you calculate the two offseted lines, use the INTERS function to get the O2 point.

Posted

Maybe this will make the matter clearer:

(setq dist1st 5.0
     dist2nd 7.5)

(setq pointP1 (getpoint)
     pointP2 (getpoint)
     pointP3 (getpoint))

(setq angle1st (angle pointP1 pointP2)
     angle2nd (angle pointP2 pointP3))

(setq pointO1  (polar pointP1 (+ angle1st (* 0.5 pi)) dist1st)
     pointO2a (polar pointP2 (+ angle1st (* 0.5 pi)) dist1st)
     pointO2b (polar pointP2 (+ angle2nd (* 0.5 pi)) dist2nd)
     pointO3  (polar pointP3 (+ angle2nd (* 0.5 pi)) dist2nd))

(setq pointO2 (inters pointO1 pointO2a pointO2b pointO3 nil))

(command "_LINE" "non" pointO1 "non" pointO2 "non" pointO3 "")

Posted

Thanks MSasu, I completed topic #1.

 

The idea presented is a bit laborious because I have several points type O2, O3, but good.

Posted

Check out draw walls.lsp or multiline.lsp you can work out parrallel lines with out inters.

 

I would paste code but its copyrited. It draws 2 or 4 lines.

3dhouse.jpg

Posted

I found some of what you said, thanks for the idea.

Posted

Thanks so much Lee.

Posted

Out of curiosity, is those were pipes with different diameters, how are you going to connect them at ends? Usually this is done with a diameter transition piece.

The solution showed above looks good on XoY, but please pay attention that there will be a gap on Z axis.

Posted (edited)

Picture attached is a theoretical section (longitudinal profile) along a pipeline: Results direction planimetric

(which is X in AutoCAD) and Z axis (which is Y in AutoCAD). In practice it will use a transition piece (reduction).

 

I have attached an example. View cloud areas!

Pipe Exemple.dwg

Edited by Costinbos77
Posted

I understand now. Thank you for the explanation.

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