boids : floking & swarm & scool try

[bluatigro]

this i want to do a long time :
create a array of boid's that
togeter form a swarm or flock or scool

this can be used for sheep [ flock ] brids [ swarm ] and fish [ scool ]

i m not jet ready to code this

a flock , swarm or scool has 4 instruction's :
1 : steer to the midle swarm
2 : don't hit nabor's
3 : steer to the same direction of swarm
4 : some random stering

and in case of a predator :
5 : steer away from predator

until now i coded only rule 4 :

WindowWidth = DisplayWidth
WindowHeight = DisplayHeight
global winx , winy , pi , animalmax , state$
winx = WindowWidth
winy = WindowHeight
pi = atn( 1 ) * 4
animalmax = 20
state$ = "left right forwart"
dim a.angle( animalmax ) , a.state$( animalmax )  , a.tel( animalmax )
dim a.x( animalmax ) , a.y( animalmax )
nomainwin
open "boids sim" for graphics as #m
 #m "trapclose [quit]"
 for i = 0 to 36
   call sprite.clear 60 , 60
''    a1 = 0
''    b1 = 25
''    a2 = 10
''    b2 = -25
''    a3 = -10
''    b3 = -25
''    call rotate a1,b1 , i * pi / 18
''    call rotate a2,b2 , i * pi / 18
''    call rotate a3,b3 , i * pi / 18
''    call sprite.triangle a1 + 30 , b1 + 30 _
''    , a2 + 30 , b2 + 30 , a3 + 30 , b3 + 30 , "blue"
     call sprite.ellipse 30,30 , 30,30 _
     , "red" , "red" , 1
   a = 7
   b = 7
   call rotate a,b , i * pi / 18
   call sprite.ellipse a + 30 , b + 30 , 10 , 10 _
   , "black" , "white" , 1
   call sprite.ellipse a + 30 , b + 30 , 5 , 5 _
   , "black" , "black" , 1
   a = -7
   b = 7
   call rotate a,b , i * pi / 18
   call sprite.ellipse a + 30 , b + 30 , 10 , 10 _
   , "black" , "white" , 1
   call sprite.ellipse a + 30 , b + 30 , 5 , 5 _
   , "black" , "black", 1

   call sprite.getbmp "q" ; i
   anim$ = anim$ + " q" ; i
 next i
 for i = 0 to animalmax
   #m "addsprite animal_" ; i ; anim$
   a.x( i ) = range( 0 , winx - 60 )
   a.y( i ) = range( 0 , winy - 60 )
  dice = int( range( 0 , 36 ) )
   #m "spriteimage animal_" ; i ; " q" _
   ; dice
   a.angle( i ) = dice
   a.state$( i ) = "forwart"
   a.tel( i ) = int( range( 0 , 50 ) )
 next i
 #m "fill green"
 #m "getbmp bbmp 0 0 1 1"
 #m "background bbmp"
 timer 40 , [timer]
wait
[quit]
 close #m
end
[timer]
 scan
 for i = 0 to animalmax
    dx = 0
    dy = 1
    #m "spritexy? animal_" ; i ; " x y"
    select case a.state$( i )
      case "left"
        a.angle( i ) = ( a.angle( i ) + 1 ) mod 36
      case "right"
        a.angle( i ) = ( a.angle( i ) - 1 ) mod 36
      case else '' forwart
    end select
    #m "spriteimage animal_" ; i ; " q" ; a.angle( i )
    a.tel( i ) = a.tel( i ) - 1
    if a.tel <= 0 then
      a.tel( i ) = int( range( 10 , 70 ) )
      a.state$( i ) = word$( state$ , int( range( 1 , 4 ) ) )
    end if
    call rotate dx , dy , a.angle( i ) * pi / 18
    a.x( i ) = a.x( i ) + dx
    a.y( i ) = a.y( i ) + dy
    if a.x( i ) < 0 then a.x( i ) = winx - 60
    if a.x( i ) > winx - 60 then a.x( i ) = 0
    if a.y( i ) < 0 then a.y( i ) = winy - 60
    if a.y( i ) > winy - 60 then a.y( i ) = 0
    x = int( a.x( i ) )
    y = int( a.y( i ) )
    #m "spritexy animal_" ; i _
    ; " " ; x ; " " ; y
 next i
 #m "drawsprites"
wait

function range( low , high )
 range = rnd(0) * ( high - low ) +  low
end function

sub rotate byref k , byref l , r
 s = sin( r )
 c = cos( r )
 hk = k * c - l * s
 hl = k * s + l * c
 k = hk
 l = hl
end sub

function atan2( x , y )
 if y = 0 then
   if x > 0 then
     angle = pi / 2
   else
     if x < 0 then
       angle = 0 - pi / 2
     else
       atan2 = 20
       exit function
     end if
   end if
 end if
 if x < 0 then
   angle = atn( x / y ) + pi
 else
   angle = atn( x / y )
 end if
 if angle < 0-pi then
   angle = angle + pi * 2
 end if
 if angle > pi then
   angle = angle - pi * 2
 end if
 atan2 = angle
end function

''bluatigro 23 apr 2017
''sprite module

[sprite]
 global sprite.width , sprite.height
return

sub sprite.clear w , h
   #m "fill white"
   #m "goto 0 " ; h
   #m "size 1"
   #m "down"
   #m "color black"
   #m "backcolor black"
   #m "boxfilled " ; w ; " " ; h * 2
   #m "up"
   sprite.width = w
   sprite.height = h
end sub

sub swap byref a , byref b
 h = a
 a = b
 b = h
end sub

sub sprite.triangle x1 , y1 , x2 , y2 , x3 , y3 , clr$
 if y1 = y2 then y1 = y1 - 1e-10
 if y2 = y3 then y3 = y3 + 1e-10
 if y1 > y3 then
   call swap y1 , y3
   call swap x1 , x3
 end if
 if y1 > y2 then
   call swap y1 , y2
   call swap x1 , x2
 end if
 if y2 > y3 then
   call swap y2 , y3
   call swap x2 , y3
 end if
 #m "size 1"
 for i = y1 to y3
   a = x1 + ( x3 - x1 ) * (i-y1) / ( y3 - y1 )
   if i < y2 then
     b = x1 + ( x2 - x1 ) * (i-y1) / ( y2 - y1 )
   else
     b = x2 + ( x3 - x2 ) * (i-y2) / ( y3 - y2 )
   end if
 #m "color black"
 #m "down"
 #m "line " ; a ; " " ; i _
 ; " " ; b ; " " ; i
 #m "up"
 #m "color " ; clr$
 #m "down"
 #m "line " ; a ; " " ; i + sprite.height _
 ; " " ; b ; " " ; i + sprite.height
 #m "up"

 next i
 #m "flush"
end sub

sub sprite.rectangle x1,y1,x2,y2,clr$
 #m "goto " ; x1 ; " " ; y1
 #m "size 1"
 #m "color black"
 #m "backcolor black"
 #m "down"
 #m "boxfilled " ; x2 ; " " ; y2
 #m "up"
 #m "goto " ; x1 ; " " ; y1 + sprite.height
 #m "color " ; clr$
 #m "backcolor " ; clr$
 #m "down"
 #m "boxfilled " ; x2 ; " " ; y2 + 60
 #m "up"
end sub

sub sprite.ellipse x,y,dx,dy,clr$,bclr$,size
   #m "goto " ; x ; " " ; y
   #m "size " ; size
   #m "down"
   #m "color black"
   #m "backcolor black"
   #m "ellipsefilled " ; dx ; " " ; dy
   #m "up"
   #m "goto " ; x ; " " ; y + sprite.height
   #m "down"
   #m "color " ; clr$
   #m "backcolor " ; bclr$
   #m "ellipsefilled " ; dx ; " " ; dy
   #m "up"
end sub

sub sprite.pie x,y,dx,dy,a,b,clr$,bclr$,size
   #m "goto " ; x ; " " ; y
   #m "size " ; size
   #m "down"
   #m "color black"
   #m "backcolor black"
   #m "piefilled " ; dx ; " " ; dy _
   ; " " ; a ; " " ; b
   #m "up"
   #m "goto " ; x ; " " ; y + sprite.height
   #m "down"
   #m "color " ; clr$
   #m "backcolor " ; bclr$
   #m "piefilled " ; dx ; " " ; dy _
   ; " " ; a ; " " ; b
   #m "up"
end sub

sub sprite.line x1,y1 , x2,y2 , clr$ , size
 #m "color black"
 #m "size " ; size
 #m "down"
 #m "line " ; x1 ; " " ; y1 _
 ; " " ; x2 ; " " ; y2
 #m "up"
 #m "color " ; clr$
 #m "down"
 #m "line " ; x1 ; " " ; y1 + sprite.height _
 ; " " ; x2 ; " " ; y2 + sprite.height
 #m "up"
end sub

sub sprite.getbmp bmp$
 #m "getbmp " ; bmp$ ; " 0 0 " _
 ; sprite.width ; " " ; sprite.height * 2
end sub



error :
if i use the triangle code i get strage effect's

[B+]

Hi bluatigro,

I tried your code and those critters are cute! all it takes is a bubble with 2 eyes.

To me, they are just kind of floating around randomly?
The flocking and/or schooling is not apparent, maybe try having them flock and school around current mouse position?
Also scanning the code, I am not seeing detection of closeness of 1 critter to all the others, maybe I missed it?
Also it would be cool if the eyes were pointed into the direction they are moving.

[bluatigro]

@ b+ :
i did not jet implement the other code
i only build the random steer code
this is on the edge on what i can code

i want help whit the other stering rules

update :
i aperently did not post the last version
so here it is :

''bluatigro 24 apr 2018
''boid's sim

WindowWidth = DisplayWidth
WindowHeight = DisplayHeight
global winx , winy , pi , animalmax , state$
winx = WindowWidth
winy = WindowHeight
pi = atn( 1 ) * 4
animalmax = 20
state$ = "left right forwart"
dim a.angle( animalmax ) , a.state$( animalmax )  , a.tel( animalmax )
dim a.x( animalmax ) , a.y( animalmax )
nomainwin
open "boids sim" for graphics as #m
 #m "trapclose [quit]"
 for i = 0 to 36
   call sprite.clear 60 , 60
''    a1 = 0
''    b1 = 25
''    a2 = 10
''    b2 = -25
''    a3 = -10
''    b3 = -25
''    call rotate a1,b1 , i * pi / 18
''    call rotate a2,b2 , i * pi / 18
''    call rotate a3,b3 , i * pi / 18
''    call sprite.triangle a1 + 30 , b1 + 30 _
''    , a2 + 30 , b2 + 30 , a3 + 30 , b3 + 30 , "blue"
     call sprite.ellipse 30,30 , 30,30 _
     , "red" , "red" , 1
   a = 7
   b = 7
   call rotate a,b , i * pi / 18
   call sprite.ellipse a + 30 , b + 30 , 10 , 10 _
   , "black" , "white" , 1
   call sprite.ellipse a + 30 , b + 30 , 5 , 5 _
   , "black" , "black" , 1
   a = -7
   b = 7
   call rotate a,b , i * pi / 18
   call sprite.ellipse a + 30 , b + 30 , 10 , 10 _
   , "black" , "white" , 1
   call sprite.ellipse a + 30 , b + 30 , 5 , 5 _
   , "black" , "black", 1

   call sprite.getbmp "q" ; i
   anim$ = anim$ + " q" ; i
 next i
 for i = 0 to animalmax
   #m "addsprite animal_" ; i ; anim$
   a.x( i ) = range( 0 , winx - 60 )
   a.y( i ) = range( 0 , winy - 60 )
  dice = int( range( 0 , 36 ) )
   #m "spriteimage animal_" ; i ; " q" _
   ; dice
   a.angle( i ) = dice
   a.state$( i ) = "forwart"
   a.tel( i ) = int( range( 0 , 50 ) )
 next i
 #m "fill green"
 #m "getbmp bbmp 0 0 1 1"
 #m "background bbmp"
 #m "when characerInput [key]"
 #m "setfocus"
 timer 40 , [timer]
wait
[key]
 key$ = right$( Inkey$ , 1 )
 if key$ <> chr$( _VK_ESCAPE ) then wait
[quit]
 close #m
end
[timer]
 scan
 for i = 0 to animalmax
    dx = 0
    dy = 1
    #m "spritexy? animal_" ; i ; " x y"
    select case a.state$( i )
      case "left"
        a.angle( i ) = ( a.angle( i ) + 1 ) mod 36
      case "right"
        a.angle( i ) = ( a.angle( i ) - 1 ) mod 36
      case else '' forwart
    end select
    #m "spriteimage animal_" ; i ; " q" ; a.angle( i )
    a.tel( i ) = a.tel( i ) - 1
    if a.tel <= 0 then
      a.tel( i ) = int( range( 10 , 70 ) )
      a.state$( i ) = word$( state$ , int( range( 1 , 4 ) ) )
    end if
    call rotate dx , dy , a.angle( i ) * pi / 18
    a.x( i ) = a.x( i ) + dx
    a.y( i ) = a.y( i ) + dy
    if a.x( i ) < 0 then a.x( i ) = winx - 60
    if a.x( i ) > winx - 60 then a.x( i ) = 0
    if a.y( i ) < 0 then a.y( i ) = winy - 60
    if a.y( i ) > winy - 60 then a.y( i ) = 0
    x = int( a.x( i ) )
    y = int( a.y( i ) )
    #m "spritexy animal_" ; i _
    ; " " ; x ; " " ; y
 next i
 #m "drawsprites"
wait

function range( low , high )
 range = rnd(0) * ( high - low ) +  low
end function

sub rotate byref k , byref l , r
 s = sin( r )
 c = cos( r )
 hk = k * c - l * s
 hl = k * s + l * c
 k = hk
 l = hl
end sub

function atan2( x , y )
 if y = 0 then
   if x > 0 then
     angle = pi / 2
   else
     if x < 0 then
       angle = 0 - pi / 2
     else
       atan2 = 20
       exit function
     end if
   end if
 end if
 if x < 0 then
   angle = atn( x / y ) + pi
 else
   angle = atn( x / y )
 end if
 if angle < 0-pi then
   angle = angle + pi * 2
 end if
 if angle > pi then
   angle = angle - pi * 2
 end if
 atan2 = angle
end function

''bluatigro 23 apr 2017
''sprite module

[sprite]
 global sprite.width , sprite.height
return

sub sprite.clear w , h
   #m "fill white"
   #m "goto 0 " ; h
   #m "size 1"
   #m "down"
   #m "color black"
   #m "backcolor black"
   #m "boxfilled " ; w ; " " ; h * 2
   #m "up"
   sprite.width = w
   sprite.height = h
end sub

sub swap byref a , byref b
 h = a
 a = b
 b = h
end sub

sub sprite.triangle x1 , y1 , x2 , y2 , x3 , y3 , clr$
 if y1 = y2 then y1 = y1 - 1e-10
 if y2 = y3 then y3 = y3 + 1e-10
 if y1 > y3 then
   call swap y1 , y3
   call swap x1 , x3
 end if
 if y1 > y2 then
   call swap y1 , y2
   call swap x1 , x2
 end if
 if y2 > y3 then
   call swap y2 , y3
   call swap x2 , y3
 end if
 #m "size 1"
 for i = y1 to y3
   a = x1 + ( x3 - x1 ) * (i-y1) / ( y3 - y1 )
   if i < y2 then
     b = x1 + ( x2 - x1 ) * (i-y1) / ( y2 - y1 )
   else
     b = x2 + ( x3 - x2 ) * (i-y2) / ( y3 - y2 )
   end if
 #m "color black"
 #m "down"
 #m "line " ; a ; " " ; i _
 ; " " ; b ; " " ; i
 #m "up"
 #m "color " ; clr$
 #m "down"
 #m "line " ; a ; " " ; i + sprite.height _
 ; " " ; b ; " " ; i + sprite.height
 #m "up"

 next i
 #m "flush"
end sub

sub sprite.rectangle x1,y1,x2,y2,clr$
 #m "goto " ; x1 ; " " ; y1
 #m "size 1"
 #m "color black"
 #m "backcolor black"
 #m "down"
 #m "boxfilled " ; x2 ; " " ; y2
 #m "up"
 #m "goto " ; x1 ; " " ; y1 + sprite.height
 #m "color " ; clr$
 #m "backcolor " ; clr$
 #m "down"
 #m "boxfilled " ; x2 ; " " ; y2 + 60
 #m "up"
end sub

sub sprite.ellipse x,y,dx,dy,clr$,bclr$,size
   #m "goto " ; x ; " " ; y
   #m "size " ; size
   #m "down"
   #m "color black"
   #m "backcolor black"
   #m "ellipsefilled " ; dx ; " " ; dy
   #m "up"
   #m "goto " ; x ; " " ; y + sprite.height
   #m "down"
   #m "color " ; clr$
   #m "backcolor " ; bclr$
   #m "ellipsefilled " ; dx ; " " ; dy
   #m "up"
end sub

sub sprite.pie x,y,dx,dy,a,b,clr$,bclr$,size
   #m "goto " ; x ; " " ; y
   #m "size " ; size
   #m "down"
   #m "color black"
   #m "backcolor black"
   #m "piefilled " ; dx ; " " ; dy _
   ; " " ; a ; " " ; b
   #m "up"
   #m "goto " ; x ; " " ; y + sprite.height
   #m "down"
   #m "color " ; clr$
   #m "backcolor " ; bclr$
   #m "piefilled " ; dx ; " " ; dy _
   ; " " ; a ; " " ; b
   #m "up"
end sub

sub sprite.line x1,y1 , x2,y2 , clr$ , size
 #m "color black"
 #m "size " ; size
 #m "down"
 #m "line " ; x1 ; " " ; y1 _
 ; " " ; x2 ; " " ; y2
 #m "up"
 #m "color " ; clr$
 #m "down"
 #m "line " ; x1 ; " " ; y1 + sprite.height _
 ; " " ; x2 ; " " ; y2 + sprite.height
 #m "up"
end sub

sub sprite.getbmp bmp$
 #m "getbmp " ; bmp$ ; " 0 0 " _
 ; sprite.width ; " " ; sprite.height * 2
end sub



[B+]

Ah, well that explains it!

I think I will give it a go myself, without sprites for testing. It might be interesting...

[B+]

Here is some code for early test to get the critters pointed at the mouse (and where they will heading):

'Mouse school early test.txt for JB 2.0 B+ 2018-04-24

'from: star mouse chaser.bas 01 - back to JB
'from: star mouse chaser.bas for SmallBASIC 0.12.0 2015-11-09 MGA/B+
'from: code is based on code: mouse chaser by tsh73
'for the Just Basic contest, November 2008, I am 7 years late
'AND Combined with (mostly from here):
'Arrow test.txt for Just Basic v1.01 [B+=MGA] 2017-05-09

NoMainWin
global xmax, ymax, pi, mx, my
xmax = 1200 : ymax = 700 : pi = acs(-1)

WindowWidth = xmax + 8
WindowHeight = ymax + 32
UpperLeftX = 100
UpperLeftY = 40
Open "Mouse school early test" For Graphics_nsb_nf As #g
#g "trapclose quit"
#g "setfocus"
#g "when leftButtonUp lButtonUp"
#g "when characterInput charIn"
#g "when mouseMove move"
#g "down"
#g "fill black"
#g "color yellow"

na = 200
dim x(na), y(na)
for i = 1 to na
   x(i) = rand(0, xmax)
   y(i) = rand(0, ymax)
next

while 1
   scan
   #g "cls"
   #g "fill black"
   for i = 1 to na
       ra = atan2(my-y(i), mx-x(i)) '  + pi kind of interesting too
       call arrow x(i), y(i), ra, .2*sqr((mx-x(i))^2 + (my-y(i))^2)
   next
   #g "flush"
   call pause 1000
wend
wait

'---------------- windows setup calls

sub quit H$
   close #H$
   end
end sub

sub lButtonUp H$, mx, my  'must have handle and mouse x,y
   call quit H$
end sub

sub charIn H$, c$
   call quit H$
end sub

sub move H$, MouseX, MouseY
   mx = MouseX
   my = MouseY
end sub

'--------------- important subs for this program

sub arrow x0, y0, rAngle, distance
   x2 = x0 - .1 * distance * cos(rAngle - .25 * pi)
   y2 = y0 - .1 * distance * sin(rAngle - .25 * pi)
   #g "line ";x0;" ";y0;" ";x2;" ";y2
   x2 = x0 - .1 * distance * cos(rAngle + .25 * pi)
   y2 = y0 - .1 * distance * sin(rAngle + .25 * pi)
   #g "line ";x0;" ";y0;" ";x2;" ";y2
   x2 = x0 - distance * cos(rAngle)
   y2 = y0 - distance * sin(rAngle)
   #g "line ";x0;" ";y0;" ";x2;" ";y2
   for i = .8 * distance to distance step 3
       x1 = x0 - i * cos(rAngle)
       y1 = y0 - i * sin(rAngle)
       x2 = x1 - .1 * distance * cos(rAngle - .25 * pi)
       y2 = y1 - .1 * distance * sin(rAngle - .25 * pi)
       #g "line ";x1;" ";y1;" ";x2;" ";y2
       x2 = x1 - .1 * distance * cos(rAngle + .25 * pi)
       y2 = y1 - .1 * distance * sin(rAngle + .25 * pi)
       #g "line ";x1;" ";y1;" ";x2;" ";y2
   next
end sub

Function atan2(y,x) 'thanks Andy Amaya
   'atan2 is a function which determines the angle between points
   'x1, y1 and x2, y2. The angle returned is in radians
   'The angle returned is always in the range of
   '-PI to PI radians (-180 to 180 degrees)
   '==============================================================
   'NOTE the position of Y and X arguments
   'This keeps atan2 function same as other language versions
   '==============================================================
  If x = 0 Then
      If y < 0 Then
           atan2 = -1.5707963267948967
       Else
           atan2 = 1.5707963267948967
       End If
  Else
      chk = atn(y/x)
      If x < 0 Then
          If y < 0 Then
               chk = chk - 3.1415926535897932
           Else
               chk = chk + 3.1415926535897932
           End If
      End If
       atan2 = chk
  End If
End Function

'----------------- supplementary handy subs

sub pause mil   'tsh version has scan built-in
   t0 = time$("ms")
   while time$("ms") < t0 + mil : scan : wend
end sub

function rand(lo, hi)
   rand = int((hi - lo + 1) * rnd(0)) + lo
end function

I will probably be using tsh73 stuff from mouse chaser later.

[B+]

When on the move, they sure bunch up fast!

'Mouse school bunching critters.txt for JB 2.0 B+ 2018-04-24

'from: star mouse chaser.bas 01 - back to JB
'from: star mouse chaser.bas for SmallBASIC 0.12.0 2015-11-09 MGA/B+
'from: code is based on code: mouse chaser by tsh73
'for the Just Basic contest, November 2008, I am 7 years late
'AND Combined with
'Arrow test.txt for Just Basic v1.01 [B+=MGA] 2017-05-09

NoMainWin
global xmax, ymax, pi, mx, my
xmax = 1200 : ymax = 700 : pi = acs(-1)

WindowWidth = xmax + 8
WindowHeight = ymax + 32
UpperLeftX = 100
UpperLeftY = 40
Open "Mouse school" For Graphics_nsb_nf As #g
#g "trapclose quit"
#g "setfocus"
#g "when leftButtonUp lButtonUp"
#g "when characterInput charIn"
#g "when mouseMove move"
#g "down"
#g "fill black"
#g "color yellow"

na = 100
dim x(na), y(na), v(na)
for i = 1 to na
   x(i) = rand(0, xmax)
   y(i) = rand(0, ymax)
   v(i) = rand(100, 500)
next

while 1
   scan
   #g "cls"
   #g "fill black"
   for i = 1 to na
       d = sqr((mx - x(i))^2 + (my - y(i))^2)
       ra = atan2(my - y(i), mx - x(i)) '  + pi kind of interesting too
       call critter x(i), y(i), ra, .05 * d
       x(i) = x(i) + .05 * v(i) * cos(ra)
       y(i) = y(i) + .05 * v(i) * sin(ra)
   next
   #g "flush"
   call pause 100
wend
wait

'---------------- windows setup calls

sub quit H$
   close #H$
   end
end sub

sub lButtonUp H$, mx, my  'must have handle and mouse x,y
   call quit H$
end sub

sub charIn H$, c$
   call quit H$
end sub

sub move H$, MouseX, MouseY
   mx = MouseX
   my = MouseY
end sub

'--------------- important subs for this program

sub critter x, y, ra, s
   #g "color black"
   #g "backcolor darkgreen"
   #g "place ";x;" ";y;"; circlefilled ";s
   x1 = x + .75*s * cos(ra - pi/9)
   y1 = y + .75*s * sin(ra - pi/9)
   x2 = x + .75*s * cos(ra + pi/9)
   y2 = y + .75*s * sin(ra + pi/9)
   #g "color white"
   #g "backcolor white"
   #g "place ";x1;" ";y1;"; circlefilled ";.25*s
   #g "place ";x2;" ";y2;"; circlefilled ";.25*s
   x3 = x1 + .125 * s * cos(ra)
   y3 = y1 + .125 * s * sin(ra)
   x4 = x2 + .125 * s * cos(ra)
   y4 = y2 + .125 * s * sin(ra)
   #g "color black"
   #g "backcolor black"
   #g "place ";x3;" ";y3;"; circlefilled ";.125*s
   #g "place ";x4;" ";y4;"; circlefilled ";.125*s
end sub

sub arrow x0, y0, rAngle, distance
   x2 = x0 - .1 * distance * cos(rAngle - .25 * pi)
   y2 = y0 - .1 * distance * sin(rAngle - .25 * pi)
   #g "line ";x0;" ";y0;" ";x2;" ";y2
   x2 = x0 - .1 * distance * cos(rAngle + .25 * pi)
   y2 = y0 - .1 * distance * sin(rAngle + .25 * pi)
   #g "line ";x0;" ";y0;" ";x2;" ";y2
   x2 = x0 - distance * cos(rAngle)
   y2 = y0 - distance * sin(rAngle)
   #g "line ";x0;" ";y0;" ";x2;" ";y2
   for i = .8 * distance to distance step 3
       x1 = x0 - i * cos(rAngle)
       y1 = y0 - i * sin(rAngle)
       x2 = x1 - .1 * distance * cos(rAngle - .25 * pi)
       y2 = y1 - .1 * distance * sin(rAngle - .25 * pi)
       #g "line ";x1;" ";y1;" ";x2;" ";y2
       x2 = x1 - .1 * distance * cos(rAngle + .25 * pi)
       y2 = y1 - .1 * distance * sin(rAngle + .25 * pi)
       #g "line ";x1;" ";y1;" ";x2;" ";y2
   next
end sub

Function atan2(y,x) 'thanks Andy Amaya
   'atan2 is a function which determines the angle between points
   'x1, y1 and x2, y2. The angle returned is in radians
   'The angle returned is always in the range of
   '-PI to PI radians (-180 to 180 degrees)
   '==============================================================
   'NOTE the position of Y and X arguments
   'This keeps atan2 function same as other language versions
   '==============================================================
  If x = 0 Then
      If y < 0 Then
           atan2 = -1.5707963267948967
       Else
           atan2 = 1.5707963267948967
       End If
  Else
      chk = atn(y/x)
      If x < 0 Then
          If y < 0 Then
               chk = chk - 3.1415926535897932
           Else
               chk = chk + 3.1415926535897932
           End If
      End If
       atan2 = chk
  End If
End Function

'----------------- supplementary handy subs

sub pause mil   'tsh version has scan built-in
   t0 = time$("ms")
   while time$("ms") < t0 + mil : scan : wend
end sub

function rand(lo, hi)
   rand = int((hi - lo + 1) * rnd(0)) + lo
end function


[tsh73]

Well, making size proportional distance to mouse makes some strange effects
They move away - like far far away, in distant galaxy long time ago
But on mouse move they suddenly gets BIGGER

[B+]

Apr 24, 2018 20:55:48 GMT tsh73 said:

Well, making size proportional distance to mouse makes some strange effects
They move away - like far far away, in distant galaxy long time ago
But on mouse move they suddenly gets BIGGER

Well hopefully we can turn that frown upside down. I gave the critters constant radius and have code to keep them separated temporarily.
Looking about as I envisioned it.
'Mouse school critters separated.txt for JB 2.0 B+ 2018-04-24

'from: star mouse chaser.bas 01 - back to JB
'from: star mouse chaser.bas for SmallBASIC 0.12.0 2015-11-09 MGA/B+
'from: code is based on code: mouse chaser by tsh73
'for the Just Basic contest, November 2008, I am 7 years late
'AND Combined with
'Arrow test.txt for Just Basic v1.01 [B+=MGA] 2017-05-09
' Thanks to STxAxTIC at QB64 for method to separate particles
' Give critters constant radius

NoMainWin
global xmax, ymax, pi, mx, my
xmax = 1200 : ymax = 700 : pi = acs(-1)

WindowWidth = xmax + 8
WindowHeight = ymax + 32
UpperLeftX = 100
UpperLeftY = 40
Open "Mouse school" For Graphics_nsb_nf As #g
#g "trapclose quit"
#g "setfocus"
#g "when leftButtonUp lButtonUp"
#g "when characterInput charIn"
#g "when mouseMove move"
#g "down"
#g "fill black"
#g "color yellow"

na = 30
dim x(na), y(na), v(na), r(na)
for i = 1 to na
   x(i) = rand(0, xmax)
   y(i) = rand(0, ymax)
   v(i) = rand(5, 20)
   r(i) = rand(5, 20)
next

while 1
   scan
   #g "cls"
   #g "fill black"
   for i = 1 to na
       'radian angle to mouse
       ra = atan2(my - y(i), mx - x(i)) '  + pi kind of interesting too
       'draw it
       call critter x(i), y(i), ra, r(i)

       'separate critters for next frame and further down i line
       FOR j = i + 1 TO na
           scan

           ' The following is STATIC's adjustment of ball positions if overlapping
           ' before calcultion of new positions from collision
           ' Displacement vector and its magnitude.  Thanks STxAxTIC !
           nx = x(j) - x(i)
           ny = y(j) - y(i)
           nm = SQR(nx ^ 2 + ny ^ 2)
           IF nm < 10 + r(i) + r(j) THEN
               nx = nx / nm
               ny = ny / nm

               ' Regardless of momentum exchange, separate the balls along the lone connecting them.
               WHILE nm < 10 + r(i) +r(j)
                   scan
                   flub = 10 '  massively increased for JB to speed up code

                   x(j) = x(j) + flub * nx
                   y(j) = y(j) + flub * ny

                   x(i) = x(i) - flub * nx
                   y(i) = y(i) - flub * ny

                   nx = x(j) - x(i)
                   ny = y(j) - y(i)
                   nm = SQR(nx ^ 2 + ny ^ 2)
                   nx = nx / nm
                   ny = ny / nm
               wend
           end if
       next
       x(i) = x(i) +  v(i) * cos(ra)
       y(i) = y(i) +  v(i) * sin(ra)
   next
   #g "flush"
   call pause 100
wend
wait

'---------------- windows setup calls

sub quit H$
   close #H$
   end
end sub

sub lButtonUp H$, mx, my  'must have handle and mouse x,y
   call quit H$
end sub

sub charIn H$, c$
   call quit H$
end sub

sub move H$, MouseX, MouseY
   mx = MouseX
   my = MouseY
end sub

'--------------- important subs for this program

sub critter x, y, ra, s
   #g "color black"
   #g "backcolor darkgreen"
   #g "place ";x;" ";y;"; circlefilled ";s
   x1 = x + .75*s * cos(ra - pi/9)
   y1 = y + .75*s * sin(ra - pi/9)
   x2 = x + .75*s * cos(ra + pi/9)
   y2 = y + .75*s * sin(ra + pi/9)
   #g "color white"
   #g "backcolor white"
   #g "place ";x1;" ";y1;"; circlefilled ";.25*s
   #g "place ";x2;" ";y2;"; circlefilled ";.25*s
   x3 = x1 + .125 * s * cos(ra)
   y3 = y1 + .125 * s * sin(ra)
   x4 = x2 + .125 * s * cos(ra)
   y4 = y2 + .125 * s * sin(ra)
   #g "color black"
   #g "backcolor black"
   #g "place ";x3;" ";y3;"; circlefilled ";.125*s
   #g "place ";x4;" ";y4;"; circlefilled ";.125*s
end sub

sub arrow x0, y0, rAngle, distance
   x2 = x0 - .1 * distance * cos(rAngle - .25 * pi)
   y2 = y0 - .1 * distance * sin(rAngle - .25 * pi)
   #g "line ";x0;" ";y0;" ";x2;" ";y2
   x2 = x0 - .1 * distance * cos(rAngle + .25 * pi)
   y2 = y0 - .1 * distance * sin(rAngle + .25 * pi)
   #g "line ";x0;" ";y0;" ";x2;" ";y2
   x2 = x0 - distance * cos(rAngle)
   y2 = y0 - distance * sin(rAngle)
   #g "line ";x0;" ";y0;" ";x2;" ";y2
   for i = .8 * distance to distance step 3
       x1 = x0 - i * cos(rAngle)
       y1 = y0 - i * sin(rAngle)
       x2 = x1 - .1 * distance * cos(rAngle - .25 * pi)
       y2 = y1 - .1 * distance * sin(rAngle - .25 * pi)
       #g "line ";x1;" ";y1;" ";x2;" ";y2
       x2 = x1 - .1 * distance * cos(rAngle + .25 * pi)
       y2 = y1 - .1 * distance * sin(rAngle + .25 * pi)
       #g "line ";x1;" ";y1;" ";x2;" ";y2
   next
end sub

Function atan2(y,x) 'thanks Andy Amaya
   'atan2 is a function which determines the angle between points
   'x1, y1 and x2, y2. The angle returned is in radians
   'The angle returned is always in the range of
   '-PI to PI radians (-180 to 180 degrees)
   '==============================================================
   'NOTE the position of Y and X arguments
   'This keeps atan2 function same as other language versions
   '==============================================================
  If x = 0 Then
      If y < 0 Then
           atan2 = -1.5707963267948967
       Else
           atan2 = 1.5707963267948967
       End If
  Else
      chk = atn(y/x)
      If x < 0 Then
          If y < 0 Then
               chk = chk - 3.1415926535897932
           Else
               chk = chk + 3.1415926535897932
           End If
      End If
       atan2 = chk
  End If
End Function

'----------------- supplementary handy subs

sub pause mil   'tsh version has scan built-in
   t0 = time$("ms")
   while time$("ms") < t0 + mil : scan : wend
end sub

function rand(lo, hi)
   rand = int((hi - lo + 1) * rnd(0)) + lo
end function


[bluatigro]

update :
added a predator
the predator does not move jet
made function's of stering rules
so i can test then 1 by 1

see the report after the function cal on how wel they work

rem :
random.walk is not a stering rule

''bluatigro 24 apr 2018
''boid's sim

WindowWidth = DisplayWidth
WindowHeight = DisplayHeight
global winx , winy , pi , animalmax , state$
winx = WindowWidth
winy = WindowHeight
pi = atn( 1 ) * 4
animalmax = 20
state$ = "left right forwart"
dim a.angle( animalmax ) , a.state$( animalmax )  , a.tel( animalmax )
dim a.x( animalmax ) , a.y( animalmax ) , ry( animalmax ) , dist( animalmax )
nomainwin
open "boids sim" for graphics as #m
 #m "trapclose [quit]"
 for i = 0 to 36
   call sprite.clear 60 , 60
''    a1 = 0
''    b1 = 25
''    a2 = 10
''    b2 = -25
''    a3 = -10
''    b3 = -25
''    call rotate a1,b1 , i * pi / 18
''    call rotate a2,b2 , i * pi / 18
''    call rotate a3,b3 , i * pi / 18
''    call sprite.triangle a1 + 30 , b1 + 30 _
''    , a2 + 30 , b2 + 30 , a3 + 30 , b3 + 30 , "blue"
     call sprite.ellipse 30,30 , 30,30 _
     , "blue" , "blue" , 1
   a = 10
   b = 10
   call rotate a,b , i * pi / 18
   call sprite.ellipse a + 30 , b + 30 , 15 , 15 _
   , "black" , "white" , 1
   call sprite.ellipse a + 30 , b + 30 , 7 ,7 _
   , "black" , "black" , 1
   a = -10
   b = 10
   call rotate a,b , i * pi / 18
   call sprite.ellipse a + 30 , b + 30 , 15 , 15 _
   , "black" , "white" , 1
   call sprite.ellipse a + 30 , b + 30 , 7 , 7 _
   , "black" , "black", 1

   call sprite.getbmp "q" ; i
   anim$ = anim$ + " q" ; i
   call sprite.clear 60 , 60
''    a1 = 0
''    b1 = 25
''    a2 = 10
''    b2 = -25
''    a3 = -10
''    b3 = -25
''    call rotate a1,b1 , i * pi / 18
''    call rotate a2,b2 , i * pi / 18
''    call rotate a3,b3 , i * pi / 18
''    call sprite.triangle a1 + 30 , b1 + 30 _
''    , a2 + 30 , b2 + 30 , a3 + 30 , b3 + 30 , "blue"
   call sprite.ellipse 30,30 , 30,30 _
   , "red" , "red" , 1
   a = 10
   b = 13
   call rotate a,b , i * pi / 18
   call sprite.ellipse a + 30 , b + 30 , 15 , 15 _
   , "black" , "white" , 1
   call sprite.ellipse a + 30 , b + 30 , 7 , 7 _
   , "black" , "black" , 1
   a = -10
   b = 13
   call rotate a,b , i * pi / 18
   call sprite.ellipse a + 30 , b + 30 , 15 , 15 _
   , "black" , "white" , 1
   call sprite.ellipse a + 30 , b + 30 , 7 , 7 _
   , "black" , "black", 1

   call sprite.getbmp "p" ; i
   pred$ = pred$ + " p" ; i
 next i
 for i = 0 to animalmax
   #m "addsprite animal_" ; i ; anim$
   a.x( i ) = range( 0 , winx - 60 )
   a.y( i ) = range( 0 , winy - 60 )
  dice = int( range( 0 , 36 ) )
   #m "spriteimage animal_" ; i ; " q" _
   ; dice
   a.angle( i ) = dice
   a.state$( i ) = "forwart"
   a.tel( i ) = int( range( 0 , 50 ) )
   ry( i ) = i
 next i
 #m "addsprite predator " ; pred$
 #m "spritexy predator 100 100"
 #m "fill darkgreen"
 #m "getbmp bbmp 0 0 1 1"
 #m "background bbmp"
 #m "when characterInput [key]"
 #m "setfocus"
 timer 40 , [timer]
wait
[key]
 key$ = right$( Inkey$ , 1 )
 if key$ <> chr$( _VK_ESCAPE ) then wait
[quit]
 close #m
end
[timer]
 scan
 for i = 0 to animalmax
   dx = 0
   dy = 1
   dangle = 0
''    dangle = random.walk( i )              ''not jet good
''    dangle = dangle + dont.hit.nabor( i )  ''gives crash
''    dangle = dangle + steer.to.center( i ) ''not jet good
   dangle = dabgle + steer.as.others( i ) ''works
   dangle = dangle + steer.random( i )    ''works
''    dangle = dangle + avoid.predator( i )  ''not jet good

   a.angle( i ) = a.angle( i ) + dangle
   no = int2( a.angle( i ) )
   if no < 0 then no = no + 36
   #m "spriteimage animal_" ; i ; " q" ; no
   call rotate dx , dy , a.angle( i ) * pi / 18
   a.x( i ) = a.x( i ) + dx
   a.y( i ) = a.y( i ) + dy
   if a.x( i ) < 0 then a.x( i ) = winx - 60
   if a.x( i ) > winx - 60 then a.x( i ) = 0
   if a.y( i ) < 0 then a.y( i ) = winy - 60
   if a.y( i ) > winy - 60 then a.y( i ) = 0
   x = int( a.x( i ) )
   y = int( a.y( i ) )
   #m "spritexy animal_" ; i ; " " ; x ; " " ; y
 next i
 #m "drawsprites"
wait
function random.walk( i )
 a.tel( i ) = a.tel( i ) - 1
 if a.tel( i ) < 0 then
   a.tel( i ) = range( 5 , 18 )
   a.state$( i ) = word$( state$ , int( range( 1 , 4 ) ) )
 end if
 uit = 0
 select case a.state$( i )
   case "left"
     uit = 1
   case "right"
     uit = -1
   case else
 end select
 random.walk = uit
end function
''stering rules
function avoid.predator( i )
 i.x = a.x( i )
 i.y = a.y( i )
 #m "spritexy? predator p.x p.y"
 hoek = atan2( p.x - i.x , p.y - i.y ) / pi * 18
 q = hoek - a.angle( i )
 if q < 0 then q = q + 36
 d = length( p.x - i.x , p.y - i.y ) + 1
 if d < 90 then
   if q < 9 then
     uit = 2 / d
   end if
   if q > 27 then
     uit = -2 / d
   end if
 end if
 avoid.predator = uit
end function
function steer.random( i )
 steer.random = range( -1 , 1 )
end function
function steer.as.others( i )
 i.a = a.angle( i )
 uit = 0
 for j = 0 to animalmax
   j.a = a.angle( j )
   uit = uit + ( j.a - i.a ) mod 36
 next j
 steer.as.others = uit / animalmax / 36
end function
function steer.to.center( i )
 i.x = a.x( i )
 i.y = a.y( i )
 swarm.x = 0
 swarm.y = 0
 for j = 0 to animalmax
   swarm.x = swarm.x + a.x( j )
   swarm.y = swarm.y + a.y( j )
 next j
 swarm.x = swarm.x / animalmax
 swarm.y = swarm.y / animalmax
 hoek = atan2( swarm.x - i.x , swarm.y - i.y ) / pi * 18
 i.a = a.angle( i )
 q = hoek - i.a
 if q < 0 then q = q + 36
 if q < 18 then
   uit = -2
 else
   uit = 2
 end if
 steer.to.center = uit
end function
function dont.hit.nabor( i )
 i.x = a.x( i )
 i.y = a.y( i )
 for j = 0 to animalmax
   j.x = a.x( j )
   j.y = a.y( j )
   dist( j ) = length( i.x - j.x , i.y - j.y )
 next j
 for high = 1 to animalmax
   for low = 0 to high - 1
     if dist( ry( high ) ) < dist( ry( low ) ) then
       help = ry( high )
       ry( high ) = ry( low )
       ry( low ) = help
     end if
   next low
 next high
 b = a.angle( ry( 0 ) )
 uit = 0
 for j = 1 to 5
   a = int2( animal.angle( ry( 0 ) , ry( j ) ) / pi * 36 )
   if b < a then
     uit = uit - 1 / j
   end if
   if b > a then
     uit = uit + 1 / j
   end if
 next j
 dont.hit.nabor = uit
end function
''end stering rules
function animal.angle( a1 , a2 )
 angle = atan2( a.x( a2 ) - a.x( a1 ) , a.y( a2 ) - a.y( a1 ) )
end function
function length( x , y )
 length = sqr( x ^ 2 + y ^ 2 )
end function
function range( low , high )
 range = rnd(0) * ( high - low ) +  low
end function
function int2( x )
 if sign( x ) = -1 then x = x + 1
 int2 = int( x )
end function
function sign( x )
 uit = 0
 if x < 0 then uit = -1
 if x > 0 then uit = 1
 sign = uit
end function
sub rotate byref k , byref l , r
 s = sin( r )
 c = cos( r )
 hk = k * c - l * s
 hl = k * s + l * c
 k = hk
 l = hl
end sub

function atan2( x , y )
 if y = 0 then
   if x > 0 then
     angle = pi / 2
   else
     if x < 0 then
       angle = 0 - pi / 2
     else
       atan2 = 20
       exit function
     end if
   end if
 end if
 if x < 0 then
   angle = atn( x / y ) + pi
 else
   angle = atn( x / y )
 end if
 if angle < 0-pi then
   angle = angle + pi * 2
 end if
 if angle > pi then
   angle = angle - pi * 2
 end if
 atan2 = angle
end function

''bluatigro 23 apr 2017
''sprite module

[sprite]
 global sprite.width , sprite.height
return

sub sprite.clear w , h
   #m "fill white"
   #m "goto 0 " ; h
   #m "size 1"
   #m "down"
   #m "color black"
   #m "backcolor black"
   #m "boxfilled " ; w ; " " ; h * 2
   #m "up"
   sprite.width = w
   sprite.height = h
end sub

sub swap byref a , byref b
 h = a
 a = b
 b = h
end sub

sub sprite.triangle x1 , y1 , x2 , y2 , x3 , y3 , clr$
 if y1 = y2 then y1 = y1 - 1e-10
 if y2 = y3 then y3 = y3 + 1e-10
 if y1 > y3 then
   call swap y1 , y3
   call swap x1 , x3
 end if
 if y1 > y2 then
   call swap y1 , y2
   call swap x1 , x2
 end if
 if y2 > y3 then
   call swap y2 , y3
   call swap x2 , y3
 end if
 #m "size 1"
 for i = y1 to y3
   a = x1 + ( x3 - x1 ) * (i-y1) / ( y3 - y1 )
   if i < y2 then
     b = x1 + ( x2 - x1 ) * (i-y1) / ( y2 - y1 )
   else
     b = x2 + ( x3 - x2 ) * (i-y2) / ( y3 - y2 )
   end if
 #m "color black"
 #m "down"
 #m "line " ; a ; " " ; i _
 ; " " ; b ; " " ; i
 #m "up"
 #m "color " ; clr$
 #m "down"
 #m "line " ; a ; " " ; i + sprite.height _
 ; " " ; b ; " " ; i + sprite.height
 #m "up"

 next i
 #m "flush"
end sub

sub sprite.rectangle x1,y1,x2,y2,clr$
 #m "goto " ; x1 ; " " ; y1
 #m "size 1"
 #m "color black"
 #m "backcolor black"
 #m "down"
 #m "boxfilled " ; x2 ; " " ; y2
 #m "up"
 #m "goto " ; x1 ; " " ; y1 + sprite.height
 #m "color " ; clr$
 #m "backcolor " ; clr$
 #m "down"
 #m "boxfilled " ; x2 ; " " ; y2 + 60
 #m "up"
end sub

sub sprite.ellipse x,y,dx,dy,clr$,bclr$,size
   #m "goto " ; x ; " " ; y
   #m "size " ; size
   #m "down"
   #m "color black"
   #m "backcolor black"
   #m "ellipsefilled " ; dx ; " " ; dy
   #m "up"
   #m "goto " ; x ; " " ; y + sprite.height
   #m "down"
   #m "color " ; clr$
   #m "backcolor " ; bclr$
   #m "ellipsefilled " ; dx ; " " ; dy
   #m "up"
end sub

sub sprite.pie x,y,dx,dy,a,b,clr$,bclr$,size
   #m "goto " ; x ; " " ; y
   #m "size " ; size
   #m "down"
   #m "color black"
   #m "backcolor black"
   #m "piefilled " ; dx ; " " ; dy _
   ; " " ; a ; " " ; b
   #m "up"
   #m "goto " ; x ; " " ; y + sprite.height
   #m "down"
   #m "color " ; clr$
   #m "backcolor " ; bclr$
   #m "piefilled " ; dx ; " " ; dy _
   ; " " ; a ; " " ; b
   #m "up"
end sub

sub sprite.line x1,y1 , x2,y2 , clr$ , size
 #m "color black"
 #m "size " ; size
 #m "down"
 #m "line " ; x1 ; " " ; y1 _
 ; " " ; x2 ; " " ; y2
 #m "up"
 #m "color " ; clr$
 #m "down"
 #m "line " ; x1 ; " " ; y1 + sprite.height _
 ; " " ; x2 ; " " ; y2 + sprite.height
 #m "up"
end sub

sub sprite.getbmp bmp$
 #m "getbmp " ; bmp$ ; " 0 0 " _
 ; sprite.width ; " " ; sprite.height * 2
end sub



[bluatigro]

update :
i added a red circle
in this circle the blue boid's shoot steer away from the predator
they do not seem to react on the red predator
and sometimes they stick to the predator
so avoid.predator() has error

WHERE DO THESE STRIPES COME FROM ?


''bluatigro 24 apr 2018
''boid's sim

WindowWidth = DisplayWidth
WindowHeight = DisplayHeight
global winx , winy , pi , animalmax , state$
winx = WindowWidth
winy = WindowHeight
pi = atn( 1 ) * 4
animalmax = 20
state$ = "left right forwart"
dim a.angle( animalmax ) , a.state$( animalmax )  , a.tel( animalmax )
dim a.x( animalmax ) , a.y( animalmax ) , ry( animalmax ) , dist( animalmax )
nomainwin
open "boids sim" for graphics as #m
 #m "trapclose [quit]"
 for i = 0 to 36
   call sprite.clear 60 , 60
''    a1 = 0
''    b1 = 25
''    a2 = 10
''    b2 = -25
''    a3 = -10
''    b3 = -25
''    call rotate a1,b1 , i * pi / 18
''    call rotate a2,b2 , i * pi / 18
''    call rotate a3,b3 , i * pi / 18
''    call sprite.triangle a1 + 30 , b1 + 30 _
''    , a2 + 30 , b2 + 30 , a3 + 30 , b3 + 30 , "blue"
     call sprite.ellipse 30,30 , 30,30 _
     , "blue" , "blue" , 1
   a = 10
   b = 10
   call rotate a,b , i * pi / 18
   call sprite.ellipse a + 30 , b + 30 , 15 , 15 _
   , "black" , "white" , 1
   call sprite.ellipse a + 30 , b + 30 , 7 ,7 _
   , "black" , "black" , 1
   a = -10
   b = 10
   call rotate a,b , i * pi / 18
   call sprite.ellipse a + 30 , b + 30 , 15 , 15 _
   , "black" , "white" , 1
   call sprite.ellipse a + 30 , b + 30 , 7 , 7 _
   , "black" , "black", 1

   call sprite.getbmp "q" ; i
   anim$ = anim$ + " q" ; i
   call sprite.clear 60 , 60
''    a1 = 0
''    b1 = 25
''    a2 = 10
''    b2 = -25
''    a3 = -10
''    b3 = -25
''    call rotate a1,b1 , i * pi / 18
''    call rotate a2,b2 , i * pi / 18
''    call rotate a3,b3 , i * pi / 18
''    call sprite.triangle a1 + 30 , b1 + 30 _
''    , a2 + 30 , b2 + 30 , a3 + 30 , b3 + 30 , "blue"
   call sprite.ellipse 30,30 , 30,30 _
   , "red" , "red" , 1
   a = 10
   b = 13
   call rotate a,b , i * pi / 18
   call sprite.ellipse a + 30 , b + 30 , 15 , 15 _
   , "black" , "white" , 1
   call sprite.ellipse a + 30 , b + 30 , 7 , 7 _
   , "black" , "black" , 1
   a = -10
   b = 13
   call rotate a,b , i * pi / 18
   call sprite.ellipse a + 30 , b + 30 , 15 , 15 _
   , "black" , "white" , 1
   call sprite.ellipse a + 30 , b + 30 , 7 , 7 _
   , "black" , "black", 1

   call sprite.getbmp "p" ; i
   pred$ = pred$ + " p" ; i
 next i
 for i = 0 to animalmax
   #m "addsprite animal_" ; i ; anim$
   a.x( i ) = range( 0 , winx - 60 )
   a.y( i ) = range( 0 , winy - 60 )
  dice = int( range( 0 , 36 ) )
   #m "spriteimage animal_" ; i ; " q" _
   ; dice
   a.angle( i ) = dice
   a.state$( i ) = "forwart"
   a.tel( i ) = int( range( 0 , 50 ) )
   ry( i ) = i
 next i
 #m "addsprite predator " ; pred$
 #m "spritexy predator 100 100"
 #m "fill darkgreen"
 #m "goto 130 130"
 #m "color red"
 #m "size 5"
 #m "down"
 #m "circle 130"
 #m "up"
 #m "getbmp bbmp 0 0 " ; winx ; " " ; winy
 #m "background bbmp"
 #m "when characterInput [key]"
 #m "setfocus"
 timer 40 , [timer]
wait
[key]
 key$ = right$( Inkey$ , 1 )
 if key$ <> chr$( _VK_ESCAPE ) then wait
[quit]
 close #m
end
[timer]
 scan
 for i = 0 to animalmax
   dx = 0
   dy = 1
   dangle = 0
''    dangle = random.walk( i ) ''not jet good
''    dangle = dangle + dont.hit.nabor( i ) ''gives crash
''    dangle = dangle + steer.to.center( i ) ''not jet good
''    dangle = dangle + steer.as.others( i ) ''works
''    dangle = dangle + steer.random( i )    ''works
   dangle = dangle + avoid.predator( i )  ''not jet good

   a.angle( i ) = a.angle( i ) + dangle
   no = int2( a.angle( i ) )
   if no < 0 then no = no + 36
   #m "spriteimage animal_" ; i ; " q" ; no
   call rotate dx , dy , a.angle( i ) * pi / 18
   a.x( i ) = a.x( i ) + dx
   a.y( i ) = a.y( i ) + dy
   if a.x( i ) < 0 then a.x( i ) = winx - 60
   if a.x( i ) > winx - 60 then a.x( i ) = 0
   if a.y( i ) < 0 then a.y( i ) = winy - 60
   if a.y( i ) > winy - 60 then a.y( i ) = 0
   x = int( a.x( i ) )
   y = int( a.y( i ) )
   #m "spritexy animal_" ; i ; " " ; x ; " " ; y
 next i
 #m "drawsprites"
wait
function random.walk( i )
 a.tel( i ) = a.tel( i ) - 1
 if a.tel( i ) < 0 then
   a.tel( i ) = range( 5 , 18 )
   a.state$( i ) = word$( state$ , int( range( 1 , 4 ) ) )
 end if
 uit = 0
 select case a.state$( i )
   case "left"
     uit = 1
   case "right"
     uit = -1
   case else
 end select
 random.walk = uit
end function
function avoid.predator( i )
 i.x = a.x( i )
 i.y = a.y( i )
 #m "spritexy? predator p.x p.y"
 hoek = atan2( p.x - i.x , p.y - i.y )
 if hoek = 20 then exit function
 hoek = hoek * 18 / pi
 q = hoek - a.angle( i )
 if q < 0 then q = q + 36
 d = length( p.x - i.x , p.y - i.y ) + 1
 if d < 130 then
   if q < 9 then
     uit = 10 / d
   end if
   if q > 27 then
     uit = -10 / d
   end if
 end if
 avoid.predator = uit
end function
function steer.random( i )
 steer.random = range( -1 , 1 )
end function
function steer.as.others( i )
 i.a = a.angle( i )
 uit = 0
 for j = 0 to animalmax
   j.a = a.angle( j )
   uit = uit + ( j.a - i.a ) mod 36
 next j
 steer.as.others = uit / animalmax / 36
end function
function steer.to.center( i )
 i.x = a.x( i )
 i.y = a.y( i )
 swarm.x = 0
 swarm.y = 0
 for j = 0 to animalmax
   swarm.x = swarm.x + a.x( j )
   swarm.y = swarm.y + a.y( j )
 next j
 swarm.x = swarm.x / animalmax
 swarm.y = swarm.y / animalmax
 hoek = atan2( swarm.x - i.x , swarm.y - i.y )
 if hoek = 20 then exit function
 hoek = hoek * 18 / pi
 i.a = a.angle( i )
 q = hoek - i.a
 if q < 0 then q = q + 36
 if q < 18 then
   uit = -2
 else
   uit = 2
 end if
 steer.to.center = uit
end function
function dont.hit.nabor( i )
 i.x = a.x( i )
 i.y = a.y( i )
 for j = 0 to animalmax
   j.x = a.x( j )
   j.y = a.y( j )
   dist( j ) = length( i.x - j.x , i.y - j.y )
 next j
 for high = 1 to animalmax
   for low = 0 to high - 1
     if dist( ry( high ) ) < dist( ry( low ) ) then
       help = ry( high )
       ry( high ) = ry( low )
       ry( low ) = help
     end if
   next low
 next high
 b = a.angle( ry( 0 ) )
 uit = 0
 for j = 1 to 5
   a = int2( animal.angle( ry( 0 ) , ry( j ) ) / pi * 36 )
   if b < a then
     uit = uit - 1 / j
   end if
   if b > a then
     uit = uit + 1 / j
   end if
 next j
 dont.hit.nabor = uit
end function
function animal.angle( a1 , a2 )
 angle = atan2( a.x( a2 ) - a.x( a1 ) _
 , a.y( a2 ) - a.y( a1 ) )
end function
function length( x , y )
 length = sqr( x ^ 2 + y ^ 2 )
end function
function range( low , high )
 range = rnd(0) * ( high - low ) +  low
end function
function int2( x )
 if sign( x ) = -1 then x = x + 1
 int2 = int( x )
end function
function sign( x )
 uit = 0
 if x < 0 then uit = -1
 if x > 0 then uit = 1
 sign = uit
end function
sub rotate byref k , byref l , r
 s = sin( r )
 c = cos( r )
 hk = k * c - l * s
 hl = k * s + l * c
 k = hk
 l = hl
end sub

function atan2( x , y )
 if y = 0 then
   if x > 0 then
     angle = pi / 2
   else
     if x < 0 then
       angle = 0 - pi / 2
     else
       atan2 = 20
       exit function
     end if
   end if
 end if
 if x < 0 then
   angle = atn( x / y ) + pi
 else
   angle = atn( x / y )
 end if
 if angle < 0 - pi then
   angle = angle + pi * 2
 end if
 if angle > pi then
   angle = angle - pi * 2
 end if
 atan2 = angle
end function

''bluatigro 23 apr 2017
''sprite module

[sprite]
 global sprite.width , sprite.height
return

sub sprite.clear w , h
   #m "fill white"
   #m "goto 0 " ; h
   #m "size 1"
   #m "down"
   #m "color black"
   #m "backcolor black"
   #m "boxfilled " ; w ; " " ; h * 2
   #m "up"
   sprite.width = w
   sprite.height = h
end sub

sub swap byref a , byref b
 h = a
 a = b
 b = h
end sub

sub sprite.triangle x1 , y1 , x2 , y2 , x3 , y3 , clr$
 if y1 = y2 then y1 = y1 - 1e-10
 if y2 = y3 then y3 = y3 + 1e-10
 if y1 > y3 then
   call swap y1 , y3
   call swap x1 , x3
 end if
 if y1 > y2 then
   call swap y1 , y2
   call swap x1 , x2
 end if
 if y2 > y3 then
   call swap y2 , y3
   call swap x2 , y3
 end if
 #m "size 1"
 for i = y1 to y3
   a = x1 + ( x3 - x1 ) * (i-y1) / ( y3 - y1 )
   if i < y2 then
     b = x1 + ( x2 - x1 ) * (i-y1) / ( y2 - y1 )
   else
     b = x2 + ( x3 - x2 ) * (i-y2) / ( y3 - y2 )
   end if
 #m "color black"
 #m "down"
 #m "line " ; a ; " " ; i _
 ; " " ; b ; " " ; i
 #m "up"
 #m "color " ; clr$
 #m "down"
 #m "line " ; a ; " " ; i + sprite.height _
 ; " " ; b ; " " ; i + sprite.height
 #m "up"

 next i
 #m "flush"
end sub

sub sprite.rectangle x1,y1,x2,y2,clr$
 #m "goto " ; x1 ; " " ; y1
 #m "size 1"
 #m "color black"
 #m "backcolor black"
 #m "down"
 #m "boxfilled " ; x2 ; " " ; y2
 #m "up"
 #m "goto " ; x1 ; " " ; y1 + sprite.height
 #m "color " ; clr$
 #m "backcolor " ; clr$
 #m "down"
 #m "boxfilled " ; x2 ; " " ; y2 + 60
 #m "up"
end sub

sub sprite.ellipse x,y,dx,dy,clr$,bclr$,size
   #m "goto " ; x ; " " ; y
   #m "size " ; size
   #m "down"
   #m "color black"
   #m "backcolor black"
   #m "ellipsefilled " ; dx ; " " ; dy
   #m "up"
   #m "goto " ; x ; " " ; y + sprite.height
   #m "down"
   #m "color " ; clr$
   #m "backcolor " ; bclr$
   #m "ellipsefilled " ; dx ; " " ; dy
   #m "up"
end sub

sub sprite.pie x,y,dx,dy,a,b,clr$,bclr$,size
   #m "goto " ; x ; " " ; y
   #m "size " ; size
   #m "down"
   #m "color black"
   #m "backcolor black"
   #m "piefilled " ; dx ; " " ; dy _
   ; " " ; a ; " " ; b
   #m "up"
   #m "goto " ; x ; " " ; y + sprite.height
   #m "down"
   #m "color " ; clr$
   #m "backcolor " ; bclr$
   #m "piefilled " ; dx ; " " ; dy _
   ; " " ; a ; " " ; b
   #m "up"
end sub

sub sprite.line x1,y1 , x2,y2 , clr$ , size
 #m "color black"
 #m "size " ; size
 #m "down"
 #m "line " ; x1 ; " " ; y1 _
 ; " " ; x2 ; " " ; y2
 #m "up"
 #m "color " ; clr$
 #m "down"
 #m "line " ; x1 ; " " ; y1 + sprite.height _
 ; " " ; x2 ; " " ; y2 + sprite.height
 #m "up"
end sub

sub sprite.getbmp bmp$
 #m "getbmp " ; bmp$ ; " 0 0 " _
 ; sprite.width ; " " ; sprite.height * 2
end sub



[B+]

Hmm... all the new code is crossed out?

I noticed a red critter, predator in previous code but no reactions by other critters which just flow over the screen one side to opposite, random wiggling.

Bluatigro, you might be having trouble getting angles correctly because the normal or standard way to use arc tan for two points is to use the y difference on top, the numerator, and the x difference below as the denominator. But depending how you set things up the opposite might work.

I would try a vastly simplified study of getting the angles between two circles and moving them closer or repelling each other before adding all the other complications. This is what I tried to demo with the arrows code.

[B+]

Here is Mouse school with left mouse clicking toggling predator/prey modes:
''Mouse school critter attract or repell.txt for JB 2.0 B+ 2018-04-26

'from: star mouse chaser.bas 01 - back to JB
'from: star mouse chaser.bas for SmallBASIC 0.12.0 2015-11-09 MGA/B+
'from: code is based on code: mouse chaser by tsh73
'for the Just Basic contest, November 2008, I am 7 years late
'AND Combined with
'Arrow test.txt for Just Basic v1.01 [B+=MGA] 2017-05-09
' Thanks to STxAxTIC at QB64 for method to separate particles
' Give critters constant radius

NoMainWin
global xmax, ymax, pi, mx, my, predatorMode
xmax = 1200 : ymax = 700 : pi = acs(-1)

WindowWidth = xmax + 8
WindowHeight = ymax + 32
UpperLeftX = 100
UpperLeftY = 40
Open "Mouse school -       left click mouse to toggle mouse as predator / prey" For Graphics_nsb_nf As #g
#g "trapclose quit"
#g "setfocus"
#g "when leftButtonUp lButtonUp"
#g "when characterInput charIn"
#g "when mouseMove move"
#g "down"
#g "fill blue"
#g "color yellow"

na = 30
dim x(na), y(na), v(na), r(na)
for i = 1 to na
   x(i) = rand(0, xmax)
   y(i) = rand(0, ymax)
   v(i) = rand(5, 20)
   r(i) = rand(5, 20)
next
predatorMode = 0
while 1
   scan
   #g "cls"
   #g "fill blue"
   if predatorMode then
       #g "color brown"
       #g "backcolor darkred"
   else
       #g "color white"
       #g "backcolor green"
   end if
   #g "place ";mx;" ";my;"; circlefilled ";40
   for i = 1 to na
       'radian angle to mouse
       ra = atan2(my - y(i), mx - x(i)) '  + pi kind of interesting too
       'draw it
       call critter x(i), y(i), ra, r(i)

       'separate critters for next frame and further down i line
       FOR j = i + 1 TO na
           scan

           ' The following is STATIC's adjustment of ball positions if overlapping
           ' before calcultion of new positions from collision
           ' Displacement vector and its magnitude.  Thanks STxAxTIC !
           nx = x(j) - x(i)
           ny = y(j) - y(i)
           nm = SQR(nx ^ 2 + ny ^ 2)
           IF nm < 10 + r(i) + r(j) THEN
               nx = nx / nm
               ny = ny / nm

               ' Regardless of momentum exchange, separate the balls along the lone connecting them.
               WHILE nm < 10 + r(i) +r(j)
                   scan
                   flub = 10 '  massively increased for JB to speed up code

                   x(j) = x(j) + flub * nx
                   y(j) = y(j) + flub * ny

                   x(i) = x(i) - flub * nx
                   y(i) = y(i) - flub * ny

                   nx = x(j) - x(i)
                   ny = y(j) - y(i)
                   nm = SQR(nx ^ 2 + ny ^ 2)
                   nx = nx / nm
                   ny = ny / nm
               wend
           end if
       next
       if predatorMode then
           x(i) = x(i) +  v(i) * cos(ra+pi)
           y(i) = y(i) +  v(i) * sin(ra+pi)
       else
           x(i) = x(i) +  v(i) * cos(ra)
           y(i) = y(i) +  v(i) * sin(ra)
       end if
   next
   #g "flush"
   call pause 100
wend
wait

'---------------- windows setup calls

sub quit H$
   close #H$
   end
end sub

sub lButtonUp H$, mx, my  'must have handle and mouse x,y
   if predatorMode then predatorMode = 0 else predatorMode = 1
end sub

sub charIn H$, c$
   call quit H$
end sub

sub move H$, MouseX, MouseY
   mx = MouseX
   my = MouseY
end sub

'--------------- important subs for this program

sub critter x, y, ra, s
   #g "color black"
   #g "backcolor darkgreen"
   #g "place ";x;" ";y;"; circlefilled ";s
   if predatorMode then
       x1 = x + .75*s * cos(ra - pi/9 + pi)
       y1 = y + .75*s * sin(ra - pi/9 + pi)
       x2 = x + .75*s * cos(ra + pi/9 + pi)
       y2 = y + .75*s * sin(ra + pi/9 + pi)
   else
       x1 = x + .75*s * cos(ra - pi/9)
       y1 = y + .75*s * sin(ra - pi/9)
       x2 = x + .75*s * cos(ra + pi/9)
       y2 = y + .75*s * sin(ra + pi/9)
   end if
   #g "color white"
   #g "backcolor white"
   #g "place ";x1;" ";y1;"; circlefilled ";.25*s
   #g "place ";x2;" ";y2;"; circlefilled ";.25*s
   if predatorMode then
       x3 = x1 + .125 * s * cos(ra + pi)
       y3 = y1 + .125 * s * sin(ra + pi)
       x4 = x2 + .125 * s * cos(ra + pi)
       y4 = y2 + .125 * s * sin(ra + pi)
   else
       x3 = x1 + .125 * s * cos(ra)
       y3 = y1 + .125 * s * sin(ra)
       x4 = x2 + .125 * s * cos(ra)
       y4 = y2 + .125 * s * sin(ra)
   end if
   #g "color black"
   #g "backcolor black"
   #g "place ";x3;" ";y3;"; circlefilled ";.125*s
   #g "place ";x4;" ";y4;"; circlefilled ";.125*s
end sub

sub arrow x0, y0, rAngle, distance
   x2 = x0 - .1 * distance * cos(rAngle - .25 * pi)
   y2 = y0 - .1 * distance * sin(rAngle - .25 * pi)
   #g "line ";x0;" ";y0;" ";x2;" ";y2
   x2 = x0 - .1 * distance * cos(rAngle + .25 * pi)
   y2 = y0 - .1 * distance * sin(rAngle + .25 * pi)
   #g "line ";x0;" ";y0;" ";x2;" ";y2
   x2 = x0 - distance * cos(rAngle)
   y2 = y0 - distance * sin(rAngle)
   #g "line ";x0;" ";y0;" ";x2;" ";y2
   for i = .8 * distance to distance step 3
       x1 = x0 - i * cos(rAngle)
       y1 = y0 - i * sin(rAngle)
       x2 = x1 - .1 * distance * cos(rAngle - .25 * pi)
       y2 = y1 - .1 * distance * sin(rAngle - .25 * pi)
       #g "line ";x1;" ";y1;" ";x2;" ";y2
       x2 = x1 - .1 * distance * cos(rAngle + .25 * pi)
       y2 = y1 - .1 * distance * sin(rAngle + .25 * pi)
       #g "line ";x1;" ";y1;" ";x2;" ";y2
   next
end sub

Function atan2(y,x) 'thanks Andy Amaya
   'atan2 is a function which determines the angle between points
   'x1, y1 and x2, y2. The angle returned is in radians
   'The angle returned is always in the range of
   '-PI to PI radians (-180 to 180 degrees)
   '==============================================================
   'NOTE the position of Y and X arguments
   'This keeps atan2 function same as other language versions
   '==============================================================
  If x = 0 Then
      If y < 0 Then
           atan2 = -1.5707963267948967
       Else
           atan2 = 1.5707963267948967
       End If
  Else
      chk = atn(y/x)
      If x < 0 Then
          If y < 0 Then
               chk = chk - 3.1415926535897932
           Else
               chk = chk + 3.1415926535897932
           End If
      End If
       atan2 = chk
  End If
End Function

'----------------- supplementary handy subs

sub pause mil   'tsh version has scan built-in
   t0 = time$("ms")
   while time$("ms") < t0 + mil : scan : wend
end sub

function rand(lo, hi)
   rand = int((hi - lo + 1) * rnd(0)) + lo
end function


[B+]

Oh hey! I decided to look up boid, thinking bluatigro might be trying for bird, I ran into this almost immediately:
www.youtube.com/watch?v=GUkjC-69vaw

and the one right after too, (not any more)
www.youtube.com/watch?v=QbUPfMXXQIY

cool!

Boid Rules (these can be turned on or off, so you get all kinds of variations of "behavior"):
1. Avoid barriers / obstacles 
2. Head in same direction as your "radial" group
3. Head or Group towards "center of gravity" so to speak
4. Space out while grouping, don't get too close or overlap.

I was using mouse position as centering / obstacle toggle.

In video's I liked how they formed particular groups, not just one big one around mouse position.

[bluatigro]

b+ :
i m not trying to hunt the mouse
but i m trying that the swarm steers itself
it is looking like what i want

[B+]

Ha! Now that I've seen the videos, I know what I want which is probably closer to what you have in mind too!

I also want to see if I could work it out myself before looking for help.

I did do a thing with dots moving around randomly and drawing lines to each other if they were within a certain distance of each other.
These connected points are the groupings I think that are needed for boid watching.

PS I called the snippets: Networking xxx, I made several versions. I will look into translating to JB.