Catia APT INFO

[bsharp]

I am trying to roll my own APT to G Code Post processor. What I am having trouble with is determining the direction of an arc. If the arc is parallel to a plane it is not a problem. The problems start when I have arc's at strange angles or crossing more than one quadrant. There is not a whole lot out there on the subject of the APT language. I could probably make it work if I understood it better.
This is a few line's from an APT file I am trying to translate.

INDIRV/ -0.86603, 0.50000, 0.00000
TLON,GOFWD/ (CIRCLE/ 0.86603, -0.50000, 0.75000,$
0.12500),ON,2,INTOF,$
(LINE/ 0.86603, -0.50000, 0.75000,$
0.80353, -0.60825, 0.75000)

I can figure out how to get the center and ending cords and build an arc.
But determining the direction is really getting me.
From what little I understand about the "INDRV" command I think it is sort of a direction vector.
If any of you know what this "INDRV" is or can some how figure out the direction of the arc from it please clue me in.

[Dan Falck]

bsharp,

You should look at a project called 'postp' on sourceforge for inspiration:
http://sourceforge.net/project/platf...group_id=85596

What you want to do has already been done in python.

Dan

[bsharp]

Thank's Dan.
But I got the arc problem figured out using Vector calculus. It nearly burnt out both sides of my brain doing it but I did it and it works slick. It will output a 360 deg arc regardless of orientation in the correct direction. I only have it working in the XY plane so far but now that I have one down the other two shouldn't be so painful.

[denjo]

this means 'in direction vector'.
it's been a long time but i used it quite a bit at mcdonnell douglas now known as boeing. we started using ncl software which will read apt. ncl gave us the graphic image we always wanted that we couldn't get using apt.

[denjo]

use 'GOLT or GORT' MEANING 'GO LEFT' or 'GO RIGHT' TO DETERMINE WHICH WAY TO MOVE THE TOOL. IT MAY ACTUALLY BE 'GOLFT' or 'GORGT'. CAN'T REMEMBER EXACTLY....LONG TIME AGO....WOW!!!

[denjo]

YOU'RE LOOKING FROM BEHIND THE TOOL AS IT IS MOVING FORWARD TO DETERMINE THE DIRECTION.

[denjo]

-TLON MEANS 'TOOL ON'
-THE CO-ORDINATES FOLLOWING 'INDIRV' IS THE VECTOR
-'GOFWD' MEANS GO FORWARD ALONG THE CIRCLE DEFINED(.125 IS THE RADIUS OR DIA.) ON LINE 2 WHICH BEGINS AT THE (INTOF)INTERSECTION OF THE DEFINED CO-ORDINATES WHICH FOLLOW.

HOPE THIS CLARIFIES.