[bb] Voronoi map by Yasha [ 1+ years ago ]

[BlitzBot]

Title : Voronoi map
Author : Yasha
Posted : 1+ years ago

Description : This function returns a greyscale image of a Voronoi cell diagram. This is mainly useful for making procedural terrains more interesting/gameplay friendly, although it also looks pretty cool.

Update: To make the image tile use

Code Select Expand

Function WrapDist(x,y,px,py)
dx = Abs(x-px)
dy = Abs(y-py)
If dx > width/2 Then dx = width-dx
If dy > height/2 Then dy = height-dy
Return Sqr( dx*dx + dy*dy )
End Function

...to get the values of dist1#, dist2#, dist3#. [/i]

Code :

Code (blitzbasic) Select Expand

Function voronoi(fx,fy,f,d=100,minh#=0,alpha#=1,seed=-1) ;Creates a voronoi map. Size, no. features, feature density,
;min. cutoff, brightness, RNDseed
Local img=CreateImage(fx,fy)
Local imgw=fx-1
Local imgh=fy-1
Local map=CreateBank((f+1)*12) ;Rather confused sub for an array
Local maxdist#,dist1#,dist2#,dist3#,temp#
Local rs,x,y,nn,px,py,pd,op,opx,opy,np,h

If seed>-1 Then rs=RndSeed():SeedRnd seed

SetBuffer ImageBuffer(img)
LockBuffer ImageBuffer(img)

For p=1 To f
PokeInt(map,p*12,Rand(0,imgw))
PokeInt(map,p*12+4,Rand(0,imgh))
If d<100 Then PokeInt(map,p*12+8,Rand(1,100))
Next

For x=0 To imgw
For y=0 To imgh
dist1#=0
dist2#=0
For nn=1 To f
px=PeekInt(map,nn*12):py=PeekInt(map,nn*12+4)
dist1=(x-px)*(x-px)+(y-py)*(y-py)
dist2=(x-opx)*(x-opx)+(y-opy)*(y-opy)
If dist1<dist2
op=nn
opx=PeekInt(map,nn*12)
opy=PeekInt(map,nn*12+4)
EndIf
Next
temp=(x-opx)*(x-opx)+(y-opy)*(y-opy)
If temp>maxdist Then maxdist=temp
Next
Next

maxdist=Sqr(Floor(maxdist))
op=1:np=1

For x=0 To imgw
For y=0 To imgh
dist1#=0
dist2#=0
dist3#=0
For nn=1 To f ;Identify nearest two neighbours
px=PeekInt(map,nn*12):py=PeekInt(map,nn*12+4)
dist1=(x-px)*(x-px)+(y-py)*(y-py)

opx=PeekInt(map,op*12):opy=PeekInt(map,op*12+4)
npx=PeekInt(map,np*12):npy=PeekInt(map,np*12+4)
dist2=(x-opx)*(x-opx)+(y-opy)*(y-opy)
dist3=(x-npx)*(x-npx)+(y-npy)*(y-npy)

If dist3<dist2 Then op=np:dist2=dist3
If dist1<dist2 Then np=op:op=nn
If op=np Then np=nn
If dist1>dist2 And dist1<dist3 Then np=nn
Next

opx=PeekInt(map,op*12):opy=PeekInt(map,op*12+4)
npx=PeekInt(map,np*12):npy=PeekInt(map,np*12+4)
h=Sqr((x-opx)*(x-opx)+(y-opy)*(y-opy))
h=Sqr((x-npx)*(x-npx)+(y-npy)*(y-npy))-h

h=(h/(maxdist)-minh)*(1/(1-minh))*(255*alpha)
If h<0 Then h=0
If h>(255*alpha) Then h=(255*alpha)
If PeekInt(map,op*12+8)>d Then h=0 ;Edits out (100-d)% of nodes
WritePixelFast(x,y,h Or (h Shl 8) Or (h Shl 16))
Next
Next

UnlockBuffer ImageBuffer(img)
SetBuffer BackBuffer()
FreeBank map

If seed>-1 Then SeedRnd rs
Return img

End Function

Comments : none...