Another animation

[tenochtitlanuk]

One of those fun things which take rather longer than you expect!

Saw on the 'net an animation that is basically like a Moire pattern- two overlapping fans rotating.  Screen grab ( static) below.

My immediate thought was to generate one 'fan'...

... and then superpose a second one using Xor drawing. Then repeat at various phases.

BUT I'D FORGOTTEN- LB's xor-plotting doesn't work when you drawbmp an image onto a graphic window!

So I tried it making each fan blade with LINES drawn by me via the Bresenham routine previously on Forum.

Result- not surprisingly when you think about it- was messy and incorrect..

Then the light dawned. Result as below. Have put the code on my website

PS You can of course CONTRArotate the two 'fans'. As above both are clockwise.

PS Don't stare at this too long!!

[Rod]

yes, a few seconds is enough, any longer and The Mad Hatter pops out the screen followed by Alice.

[tenochtitlanuk]

Remids me of what I remember of the Sixties... perhaps the contra-rotating one will help you unwind...

[tsh73]

Well, I was able to draw it with native PIEFILLED
And RULE XOR
(though I admit I use smaller scale)
nomainwin

WindowWidth = 350
WindowHeight = 390
open "XOR animation" for graphics_nsb_nf as #gr
#gr "home; down; posxy cx cy"
#gr "trapclose [quit]"

'#gr "circle 30"
'#gr "go 20"
#gr "color white"
#gr "backcolor black"
#gr "rule XOR"

pi=acs(-1)
aa=0    'radians
while 1
   x=cx+60*cos(aa)
   y=cy+60*sin(aa)
   #gr "place ";x;" ";y
   for a = 0 to 350 step 15    'degrees
       #gr "piefilled 200 200 ";a+d;" ";7
       scan
   next

   x=cx+60*cos(aa+pi)
   y=cy+60*sin(aa+pi)
   #gr "place ";x;" ";y
   for a = 0 to 350 step 15
       #gr "piefilled 200 200 ";a+d;" ";7
       scan
   next

   timer 50, [nxt]
   wait
[nxt]
   timer 0
   #gr "cls"
   d=(d+1) mod 15
   aa=aa+1/57/5
wend


wait

[quit]
   timer 0
   close #gr
   end


It got a quirk, though
after I go to menu Run|Kill basic programs, I see previous runs as it does not finish properly
I got it in LB 4.5.1, 4.04, JB 2.0
But in JB 1.01 it says "No programs to kill" - in that older version, program exits cleanly(?).

[tsh73]

Sorry cannot resist
Now it is resizable
nomainwin

'WindowWidth = 350
'WindowHeight = 390
WindowWidth = 500
WindowHeight = 540
'WindowWidth = 1000
'WindowHeight = 1000
open "Resize me! XOR animation" for graphics_nsb as #gr
#gr "home; down; posxy cx cy"
#gr "trapclose [quit]"

'#gr "circle 30"
'#gr "go 20"
#gr "color white"
#gr "backcolor black"
#gr "rule XOR"

pi=acs(-1)
aa=0    'radians
r=min(cx, cy)*0.35
R=int(2*min(cx, cy))/1.6
while 1
   x=cx+r*cos(aa)
   y=cy+r*sin(aa)
   #gr "place ";x;" ";y
   for a = 0 to 350 step 15    'degrees
       #gr "piefilled ";R;" ";R;" ";a+d;" ";7
       scan
   next

   x=cx+r*cos(aa+pi)
   y=cy+r*sin(aa+pi)
   #gr "place ";x;" ";y
   for a = 0 to 350 step 15
       #gr "piefilled ";R;" ";R;" ";a+d;" ";7
       scan
   next

   timer 50, [nxt]
   wait
[nxt]
   timer 0
   #gr "cls"
   d=(d+1) mod 15
   aa=aa+1/57/5
   #gr "home; down; posxy cx cy"
   r=min(cx, cy)*0.35
   R=int(2*min(cx, cy))/1.6
wend


wait

[quit]
   timer 0
   close #gr
   end




[Brandon Parker]

A slightly different take on the version posted by Anatoly...

NoMainWin

WindowWidth = 650
WindowHeight = 690
Open "Resize me! XOR Animation" For graphics_nsb As #gr
#gr "Home; Down; PosXY xLoc yLoc"
#gr "TrapClose quit"
#gr "Color White"
#gr "Rule XOR"
width = Int(2 * Min(xLoc, yLoc))/1.6
height = Int(2 * Min(xLoc, yLoc))/1.6
separation = Min(xLoc, yLoc) * 0.15
pi = Acs(-1)
aa = 0
aa2 = aa + pi

   While isWndOpen("#gr")
       Scan
       #gr "Rule XOR"
       #gr "BackColor Black"
       x1=xLoc+separation*cos(aa)
       y1=yLoc+separation*sin(aa)
       x2=xLoc+separation*cos(aa2)
       y2=yLoc+separation*sin(aa2)
       For a = 0 to 350 Step 15    'degrees
           #gr "Place ";x1;" ";y1
           #gr "PieFilled ";width;" ";height;" ";a+d;" ";7
           #gr "Place ";x2;" ";y2
           #gr "PieFilled ";width;" ";height;" ";a+d;" ";7
       Next a

       #gr "Flush currentFrame"
       result = LockWindowUpdate(_NULL)
       #gr "Redraw currentFrame"
       result = Sleep(250)
       result = LockWindowUpdate(Hwnd(#gr))

       #gr "Rule OVER"
       #gr "BackColor White"
       For a = 0 to 350 Step 15    'degrees
           #gr "Place ";x1;" ";y1
           #gr "PieFilled ";width;" ";height;" ";a+d;" ";7
           #gr "Place ";x2;" ";y2
           #gr "PieFilled ";width;" ";height;" ";a+d;" ";7
       Next a
       #gr "DelSegment currentFrame"
       d = (d + 1) Mod 15
       aa = aa + 1/57/5
       aa2 = aa + pi
       #gr "Home; Down; PosXY xLoc yLoc"
       width = Int(2 * Min(xLoc, yLoc))/1.6
       height = Int(2 * Min(xLoc, yLoc))/1.6
       separation = Min(xLoc, yLoc) * 0.15

   Wend
End

   Sub quit handle$
       Close #handle$
       End
   End Sub

   Function Sleep(milliseconds)
       CallDLL #kernel32, "Sleep", milliseconds    As long, _
                                   ret             As void
   End Function

   Function isWndOpen(handle$)
       On Error GoTo [Error]
           isWndOpen = Hwnd(#handle$)
       [Error]
   End Function

   Function LockWindowUpdate(hWnd)
       CallDLL #user32, "LockWindowUpdate", hWnd               As ulong, _
                                            LockWindowUpdate   As long
   End Function


{:0)

Brandon Parker