sugar dissolve

[tsh73]

Along code posted by Bluatigro at LB forum

'along 'suger lump desolve sim try' by Bluatigro
'tsh73, jun 2019
'   JB hardcore
'   We ain't need no stinkin' API
'   LOL
'       just store points in array
nomainwin
open "sugar dessolve" for graphics_nsb_nf as #gr
#gr "down"
#gr "fill black"
#gr "trapclose [quit]"

#gr "home"
#gr "posxy  cx cy"

'look at values
'#gr "\";cx;" ";cy
dim e(cx*2, cy*2)
x1 = int(cx*2/3)
y1 = int(cy*2/3)

#gr "place ";x1;" ";y1
#gr "boxfilled ";2*x1;" ";2*y1

for x = x1 to 2*x1-1
   for y = y1 to 2*y1-1
       e(x,y) =1
   next
next

'time test. Shows array filled instantly
'#gr "place ";cx;" ";cy
'#gr "circle ";30

#gr "rule xor"  'so pixel is inverted in single op (no color change needed)
k = 0
while 1
   x=int(rnd(0)*(2*cx-2))+1  'not to get out of array e
   y=int(rnd(0)*(2*cy-2))+1
   dx=int(rnd(0)*3)-1
   dy=int(rnd(0)*3)-1
   'print dx, dy   'really -1 0 1
   c1=e(x,y)
   c2=e(x+dx, y+dy)

   if c1 <> c2 then    'only if color changes
       e(x,y)=c2
       e(x+dx, y+dy)=c1
       'because of XOR it is inverted
       #gr "set ";x;" ";y
       #gr "set ";x+dx;" ";y+dy
   end if

   k = k+1
   if k  mod 1000 = 0 then
       scan
       #gr "discard"
   end if
wend

wait

[quit]
close #gr
end