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# Random heightmaps?

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Hello. I''m making a game similar to Worms, only in 3D, and for that I''ve been looking for ways to create random heightmaps on-the-fly to be used by the terrain engine (TrueVision 3D). Do any of you know where I could find a piece of code (preferrably in Visual Basic or C/C++) or small standalone utility that would generate a random heightmap and then store it in grayscale image file? Thanks in advance

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Look for a program called ''Wilbur'', or read up on something called ''Perlin noise''. All your questions will be answered.

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Why not just write your own? It really isn''t that hard. Something like this could work:

  #include #include //For Rand()//Used to "wrap" points around the bitmap#define Pnt(x,y) map[((y+SizeY)%SizeY)*SizeX+ (x+SizeX)%SizeX]void SmoothMap(short SizeX, short SizeY, char *map){ short tx,ty; short rx,ry; short nVal; //new value! for (ty=0;ty!=SizeY;++ty) { for (tx=0;tx!=SizeY;++ty) {//Gets 9 points +/- rand(-5,5); nVal = Pnt(tx,ty) + Pnt(tx-1,ty) + Pnt(tx+1,ty) + Pnt(tx,ty-1) + Pnt(tx,ty+1) + Pnt(tx-1,ty-1) + Pnt(tx+1,ty-1) + Pnt(tx+1,ty+1) + Pnt(tx-1,ty+1) + rand()%11-5; nVal = nVal/9; if (nVal<0) nVal = 0; else if (nVal > 255) nVal = 255; Pnt(tx,ty) = nVal; } }}void CreateRandomHeightMap(short SizeX, short SizeY, char *outfile, unsigned char Smooths){ FILE *out; unsigned char *hMap; unsigned long tSize; short tx,ty; tSize = SizeX*SizeY; hMap = new unsigned char[tSize]; tSize=0; for (ty=0;ty!=SizeY;++ty) { for (tx=0;tx!=SizeX;++tx) { hMap[tSize]=rand()%256; //0-255! ++tSize; } }/*Now we have a random height map... but it''s not smooth at all!So, lets smooth it out a bit!*/for (tx=0;tx!=Smooths;++tx) SmoothMap(SizeX,SizeY,map); //Smooth map out *smooths* timesout = fopen(outfile,"wb");putw(SizeX,out); //Output SizeXputw(SizeY,out); //Output SizeYtSize=0;for (ty=0;ty!=SizeY;++ty){ for (tx=0;tx!=SizeX;++tx) { putc(map[tSize],out); //Put out char! ++tSize; }}fclose(out);delete hMap;}

You can even use this at runtime, or create a file to be loaded, etc, etc.

Billy - BillyB@mrsnj.com

ps. I typed this completely in this little text window, so it may contain some errors, but this is a "simple" random terrain generator + smoother.

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Perlin noise could do the trick: http://freespace.virgin.net/hugo.elias/models/m_perlin.htm

So could something simpler to program like the fault algorithm. The fault algorithm works like this: Generate two random points. These define a line. Randomly decide whether to make one side "high" or the other "low." Then add a small constant to all points on the "high" side and subtract it from all points on the "low" side. Repeat a thousand or so times. Done.

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And remember, rand() is horribly repetitive in its lower bits, so don''t do rand()%11-5, use the more significant bits instead.

Though on second thought, maybe that''s actually ok for terrain.

-scott

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