… aka “When the Creator misplaces a parenthesis”. :)

So my first attempt to write a program to generate random but pleasing landforms for my Sim on a Stick did not go quite as expected.

Bit spikey, for instance.

But then I found a misplaced parenthesis! And things got better.

I think I am liking the algorithm…

For the curious, here is the basic (recursive, self-similar) routine, in everyone’s favorite language: Python. (Squished down to fit in the weblog here, not guaranteed to compile as-is.)

def fill_in_terrain(t,lowx,lowy,maxx,maxy): ''' Takes the input terrain, where the low-by-max ''' ''' corners are already filled in, and fills in ''' ''' everything inside those corners, by the ''' ''' Magic of Recursion. ''' if maxx-lowx<2: return t if maxy-lowy<2: return t xmid = int((lowx+maxx)/2) ymid = int((lowy+maxy)/2) hscale = (maxx - lowx) * HSCALE # first the corners if t[lowx][ymid] is None: t[lowx][ymid] = (t[lowx][lowy] + t[lowx][maxy]) / 2 + hscale - math.floor(2*hscale*random.random()) if t[maxx][ymid] is None: t[maxx][ymid] = (t[maxx][lowy] + t[maxx][maxy]) / 2 + hscale - math.floor(2*hscale*random.random()) if t[xmid][lowy] is None: t[xmid][lowy] = (t[lowx][lowy] + t[maxx][lowy]) / 2 + hscale - math.floor(2*hscale*random.random()) if t[xmid][maxy] is None: t[xmid][maxy] = (t[lowx][maxy] + t[maxx][maxy]) / 2 + hscale - math.floor(2*hscale*random.random()) # then the center if t[xmid][ymid] is None: t[xmid][ymid] = (t[lowx][ymid]+t[maxx][ymid] + t[xmid][lowy]+[xmid][maxy])/4 + hscale - math.floor(2*hscale*random.random()) # and recurse on the four quadrants t = fill_in_terrain(t,lowx,lowy,xmid,ymid) t = fill_in_terrain(t,lowx,ymid,xmid,maxy) t = fill_in_terrain(t,xmid,lowy,maxx,ymid) t = fill_in_terrain(t,xmid,ymid,maxx,maxy) return t def get_terrain(x,y): ''' returns an [x][y] array of floats representing a terrain; ''' ''' range unpredictable ''' ''' x and y ought to be powers of two, for best results. ''' ''' oh, and equal I suppose ''' answer = [ [None for a in range(y+1)] for b in range(x+1) ] answer[0][0] = 0 answer[x][0] = 0 answer[0][y] = 0 answer[x][y] = 0 answer = fill_in_terrain(answer,0,0,x,y) return answer

Fun that all these pretty hills and things come out of that little bit of (also pretty) code…

Filed under: Other worlds, pictures, scripting | Tagged: OpenSim, python, randomness, terrain | 2 Comments »