Pt translation...

Can anyone point me to a good pt translation routine that translates a 3d
point given two 3d points as the translation vector.

TIA,

Devin

 

Got it...

(defun vector_translate ( pt v1 v2 / i j vec )
(setq
vec vector_2p v1 v2)
)
(if
vec
(setq
pt
(mapcar
'(lambda (i j)
(+ i J)
)
pt
vec
)
)
)
)



(defun :VECTOR_2P (pt1 pt2 / )
(if(equal pt1 pt2 1e-10)
nil
(mapcar (function (lambda (i j) (- j i))) pt1 pt2)
)
)

Devin

 

You can define a vector by simply subtracting the beginning point from the
end point. Then simply add that vector to the existing point to obtain the
new point.

(defun GetVector (startPoint endPoint)
(mapcar '- endPoint startPoint)
)

(defun MovePoint (vector point)
(mapcar '+ point vector)
)

(MovePoint (GetVector '(3 3 0) '(5 5 0)) '(1 2 0))
(3 4 0)

 

Simplification:
(defun vector_translate (pt v1 v2)
(mapcar '+ pt v1 (mapcar '- v2)))

 

Correction:
(defun vector_translate (pt v1 v2)
(mapcar '+ pt v2 (mapcar '- v1)))

 

Thanks Bobby,

That's very simple for me to understand. Which is what I need.

Devin

 

Thanks Luis,

Will that work for 3d points?

Devin

 

Wouldn't it be rather...

(defun vector_translate (pt v1 v2)
(mapcar '+ pt (mapcar '- v1 v2))
)

 

Correction...

(defun vector_translate (pt v1 v2)
(mapcar '+ pt (mapcar '- v2 v1))
)

 

Oops forgot to thank you for the simplification. I think it will actually
work better than what I had as it will work when the vector is (0,0,0).

Thanks,

Devin

 

That version would be as good as the one
I posted. My version uses negation rather than
subraction. Both versions should be equally fast.

 

O.K. my bad. Guess I should have tested it.

Thanks,

Devin