random points on sphere... just play :)

[teknomatika]

Lee,

I changed the routine to also draw the points so random in the plane Z.

My question is whether the variable range is well stated.

 

(defun pointsphere (c r / a b p )

(setq a (acos (1- (* 2.0 (LM:rand))))
         b (* (LM:rand) (+ pi pi))
	  ;;p (list (* r (sin a) (cos b)) (* r (sin a) (sin b)) 0.0);;original 2d points;;
         [color="red"]p (list (* r (sin a) (cos b)) (* r (sin a) (sin b)) (fix (1+ (* (LM:rand)range))));;change to 3d points[/color]
   )
   (entmake
       (list
          '(0 . "POINT")
           (cons 010 (mapcar '+ c p))
           (cons 062 (fix (1+ (* (LM:rand) 254))))
           (cons 210 p)
       )
   )
)

;; Rand  -  Lee Mac
;; PRNG implementing a linear congruential generator with
;; parameters derived from the book 'Numerical Recipes'

(defun LM:rand ( / a c m )
   (setq m   4294967296.0
         a   1664525.0
         c   1013904223.0
         $xn (rem (+ c (* a (cond ($xn) ((getvar 'date))))) m)
   )
   (/ $xn m)
)

;; ArcCosine  -  Lee Mac
;; Args: -1 <= x <= 1

(defun acos ( x )
   (if (<= -1.0 x 1.0)
       (atan (sqrt (- 1.0 (* x x))) x)
   )
)

(defun c:cirp ( / [color="red"]range[/color] c r x )
       
(if
       (and
           (setq x (getint "\nNumber of Points: "))
           (setq c (getpoint "\nCenter: "))
           (setq r (getdist  "\nRadius: " c))
		[color="red"](setq range (getint "\nRange Z Coords : "))[/color]
       )
	 (repeat x (pointsphere (trans c 1 0) r))
   )
   (princ)
)

[Lee Mac]

I changed the routine to also draw the points so random in the plane Z.

 

The points were already 3D, represented by spherical coordinates; you can vary the radius to generate random points inside the sphere:

 

    (setq a (acos (1- (* 2.0 (LM:rand))))
         b (* (LM:rand) (+ pi pi))
[color=red]          r (* (LM:rand) r)[/color]
         p (list (* r (sin a) (cos b)) (* r (sin a) (sin b)) (* r (cos a)))
   )

[teknomatika]

The points were already 3D, represented by spherical coordinates; you can vary the radius to generate random points inside the sphere:

 

    (setq a (acos (1- (* 2.0 (LM:rand))))
         b (* (LM:rand) (+ pi pi))
[color=red]          r (* (LM:rand) r)[/color]
         p (list (* r (sin a) (cos b)) (* r (sin a) (sin b)) (* r (cos a)))
   )

 

Lee,

Ah, ok. Had not seen this possibility.

However, my change corresponds to that i need: A definition of the maximum value of Z coordinates, and that the final result is in the form of a circular slice.

 

Tanks again!

[teknomatika]

The points were already 3D, represented by spherical coordinates; you can vary the radius to generate random points inside the sphere:

 

    (setq a (acos (1- (* 2.0 (LM:rand))))
         b (* (LM:rand) (+ pi pi))
[color=red]          r (* (LM:rand) r)[/color]
         p (list (* r (sin a) (cos b)) (* r (sin a) (sin b)) (* r (cos a)))
   )

 

Lee, greetings.

if possible, when you have availability, I would be grateful if you could integrate in this routine an option to be able to draw in a rectangular shape.

Thank you.

I'll be waiting.

[Lee Mac]

an option to be able to draw in a rectangular shape.

 

Simply generate random points in all three axes:

(defun c:test ( / d n x y z )
   (if
       (and
           (setq n (getint "\nNumber of Points: "))
           (setq d (getcorner '(0.0 0.0) "\nSpecify Base Dimensions: "))
           (setq z (getdist   '(0.0 0.0) "\nSpecify Height: "))
           (setq x (abs (car  d))
                 y (abs (cadr d))
           )
       )
       (repeat n (randrect x y z))
   )
   (princ)
)

(defun randrect ( x y z )
   (entmake (list '(0 . "POINT") (list 10 (* (LM:rand) x) (* (LM:rand) y) (* (LM:rand) z))))
)

;; Rand  -  Lee Mac
;; PRNG implementing a linear congruential generator with
;; parameters derived from the book 'Numerical Recipes'

(defun LM:rand ( / a c m )
   (setq m   4294967296.0
         a   1664525.0
         c   1013904223.0
         $xn (rem (+ c (* a (cond ($xn) ((getvar 'date))))) m)
   )
   (/ $xn m)
)

 

I'm sure you could have worked this out

[teknomatika]

Simply generate random points in all three axes:

(defun c:test ( / d n x y z )
   (if
       (and
           (setq n (getint "\nNumber of Points: "))
           (setq d (getcorner '(0.0 0.0) "\nSpecify Base Dimensions: "))
           (setq z (getdist   '(0.0 0.0) "\nSpecify Height: "))
           (setq x (abs (car  d))
                 y (abs (cadr d))
           )
       )
       (repeat n (randrect x y z))
   )
   (princ)
)

(defun randrect ( x y z )
   (entmake (list '(0 . "POINT") (list 10 (* (LM:rand) x) (* (LM:rand) y) (* (LM:rand) z))))
)

;; Rand  -  Lee Mac
;; PRNG implementing a linear congruential generator with
;; parameters derived from the book 'Numerical Recipes'

(defun LM:rand ( / a c m )
   (setq m   4294967296.0
         a   1664525.0
         c   1013904223.0
         $xn (rem (+ c (* a (cond ($xn) ((getvar 'date))))) m)
   )
   (/ $xn m)
)

 

I'm sure you could have worked this out

 

Lee,

I am most grateful for more this.

Even tried to get a solution, but my knowledge is still basic. But slowly ....

Tanks!