Spiral

[balaporte]

This came out of teaching myself to use sin and cosine for 2D rotation, and draws a rotating spiral on the screen. I had a version that used Kevin's fat line code to make the spiral thicker the farther away it was from the center, but I can't find that now. I'll post it later if I find it.

Use the right and left arrow keys to change the direction of the spiral rotation, and ESC to exit.

PlayBASIC Code: [Select]

sw = 1024
sh = 768
sd = 32
fullscreen = Yes

OpenScreen sw,sh,sd,fullscreen + 1

setfps 60

; VARIABLES

Type spiraltype
   cx#
   cy#
   x#
   y#
   visible
EndType

spiralcount = 1080

Dim spiral(2,spiralcount) As spiraltype

For a = 1 To spiralcount Step 2
   inc b
   spiral(1,b).visible = yes
   spiral(1,b).cx# = sw/2
   spiral(1,b).cy# = sh/2
   spiral(1,b).x# = cos(a*3)*a
   spiral(1,b).y# = sin(a*3)*a
next a

; 2D scale
for a = 1 to b
   spiral(1,a).x# = spiral(1,a).x# * 0.75
   spiral(1,a).y# = spiral(1,a).y# * 0.75
next a

rotspeed# = 3

angle# = rotspeed#

; 2D rotate
for a = 1 to b
   x# = spiral(1,a).x#
   y# = spiral(1,a).y#
   spiral(1,a).x# = x#*cos(angle#)-y#*sin(angle#)
   spiral(1,a).y# = x#*sin(angle#)+y#*cos(angle#)
next a

; MAIN LOOP

repeat
   
   if rightkey() then angle# = rotspeed# :flushkeys
   if leftkey() then angle# = neg(rotspeed#) :flushkeys
   
   for a = 1 to b
      x# = spiral(1,a).x#
      y# = spiral(1,a).y#
      spiral(1,a).x# = x#*cos(angle#)-y#*sin(angle#)
      spiral(1,a).y# = x#*sin(angle#)+y#*cos(angle#)
   next a   
      
   ; DISPLAY

   cls rgb(255,0,0)

   print fps()

   ink rgb(0,0,0)

   lockbuffer

   for a = 1 to b
      if a < b 
         x1# = spiral(1,a).cx# + spiral(1,a).x#
         y1# = spiral(1,a).cy# + spiral(1,a).y#
         x2# = spiral(1,a+1).cx# + spiral(1,a+1).x#
         y2# = spiral(1,a+1).cy# + spiral(1,a+1).y#
         line x1#, y1#, x2#, y2#
      endif
   next a

   unlockbuffer
   
   sync
      
until esckey()

[monkeybot]

nice

[kevin]

yes, it's very nice..  hypnotic even  ;)


Here's a bit of tweak

PlayBASIC Code: [Select]

sw = 1024
sh = 768
sd = 32
fullscreen = Yes

OpenScreen sw,sh,sd,fullscreen + 1

;setfps 60

; VARIABLES

Type spiraltype
   cx#
   cy#
   x#
   y#
   visible
EndType

spiralcount = 1080

Dim spiral(2,spiralcount) As spiraltype

For a = 1 To spiralcount Step 2
   inc b
   spiral(1,b).visible = yes
   spiral(1,b).cx# = sw/2
   spiral(1,b).cy# = sh/2
   spiral(1,b).x# = cos(a*3)*a
   spiral(1,b).y# = sin(a*3)*a
next a

; 2D scale
for a = 1 to b
   spiral(1,a).x# = spiral(1,a).x# * 0.75
   spiral(1,a).y# = spiral(1,a).y# * 0.75
next a

rotspeed# = 3

angle# = rotspeed#

; 2D rotate
for a = 1 to b
   x# = spiral(1,a).x#
   y# = spiral(1,a).y#
   spiral(1,a).x# = x#*cos(angle#)-y#*sin(angle#)
   spiral(1,a).y# = x#*sin(angle#)+y#*cos(angle#)
next a

; MAIN LOOP
   ink rgb(0,0,0)


repeat
   
   ; Do the Clear here since it's an async fill
   ; so the gpu fills the backdrop while the rotation code does the work.   So they occur together.
   ; 
   cls rgb(255,0,0)
   if rightkey() then angle# = rotspeed# :flushkeys
   if leftkey() then angle# = neg(rotspeed#) :flushkeys

   
   ca#=cos(angle#)
   sa#=sin(angle#)
   
   for a = 1 to b
      x# = spiral(1,a).x#
      y# = spiral(1,a).y#
      spiral(1,a).x# = x#*ca#-y#*sa#
      spiral(1,a).y# = x#*sa#+y#*ca#
   next a   
      
   ; DISPLAY

   print fps()


   lockbuffer

   a=1
   x1# = spiral(1,a).cx# + spiral(1,a).x#
   y1# = spiral(1,a).cy# + spiral(1,a).y#
   for a = 2 to b
         x2# = spiral(1,a).cx# + spiral(1,a).x#
         y2# = spiral(1,a).cy# + spiral(1,a).y#
         line x1#, y1#, x2#, y2#
         x1#=x2#
         y1#=y2#
   next a

   unlockbuffer

   sync
until esckey()

[balaporte]

That makes sense...thanks. I liked the version using your fat line code better, so I'll redo that one and post.

[monkeybot]

i did it another way.
rather quick and dirty,its well past my bedtime. :)

PlayBASIC Code: [Select]

; PROJECT : Project1
; AUTHOR  : monkeybot
; CREATED : 24/02/2011
; ---------------------------------------------------------------------
explicit on
local rad#
openscreen 800,600,32,1
local sw=GetScreenWidth()
local sh=GetScreenHeight()
local x#=400
local y#=300
local c#=0
local w,q,oldx#,oldy#,a
local x2#=100
local y2#=100
;setfps (60)
do
   rad#=sw
   
   cls
   print str$(fps())
   oldx#=x#+(sin(w)*rad#)
   oldy#=y#+(cos(w)*rad#)
   lockbuffer
   for q=a to a+(360*(sh)/68); step 2
      w=WrapAngle (q)
      if x#>0 and x#<sw and y#>0 and y#<sh 
         x2#=x#+(sin(w)*rad#)
         y2#=y#+(cos(w)*rad#)
         line oldx#,oldy#,x2#,y2#
         oldx#=x2#
         oldy#=y2#
      endif
      rad#=rad#-0.25
   next 
   unlockbuffer
   a+=8   
   if a>360 then a=0
   sync
loop
waitkey