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mandelbulb http://www.volumesoffun.com/phpBB3/viewtopic.php?f=18&t=319 
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Author:  zprg [ Sun Jan 22, 2012 2:41 pm ] 
Post subject:  mandelbulb 
hey heres a code for mandelbulb (took from: http://www.treblig.org/3dbrot/3dbrot.c with maths from http://www.skytopia.com/project/fractal/mandelbulb.html ) Code: const unsigned int size=256; #define RANGE 1.2 const double xlow=RANGE; const double xhigh=RANGE; const double ylow=RANGE; const double yhigh=RANGE; const double zlow=RANGE; const double zhigh=RANGE; const unsigned int maxiterations=80; const double mandpow=8.0; double r; double valInRange(double low, double high, unsigned int size, unsigned int off) { return low+((highlow)/(double)size)*(double)off; } unsigned int doPoint(double cx, double cy, double cz) { // program from http://www.treblig.org/3dbrot/3dbrot.c double x,y,z; double newx,newy,newz; double theta,phi,rpow; //double r; unsigned int i; x=0.0; y=0.0; z=0.0; for(i=0;(i<maxiterations) && ((x*x+y*y+z*z) < 2.0);i++) { /* These maths from http://www.skytopia.com/project/fractal/mandelbulb.html */ r = sqrt(x*x + y*y + z*z ); theta = atan2(sqrt(x*x + y*y) , z); phi = atan2(y,x); rpow = pow(r,mandpow); newx = rpow * sin(theta*mandpow) * cos(phi*mandpow); newy = rpow * sin(theta*mandpow) * sin(phi*mandpow); newz = rpow * cos(theta*mandpow); x=newx+cx; y=newy+cy; z=newz+cz; } return i; } void createMandelbulb(PolyVox::SimpleVolume<PolyVox::Material8>& volData) { PolyVox::Material8 uValue=1; //This threelevel for loop iterates over every voxel in the volume for (int z = 0; z < volData.getWidth(); z++) { double fz=valInRange(zlow, zhigh, size, z); for (int y = 0; y < volData.getHeight(); y++) { double fy=valInRange(ylow, yhigh, size, y); for (int x = 0; x < volData.getDepth(); x++) { double fx=valInRange(xlow, xhigh, size, x); unsigned int val=doPoint(fx,fy,fz); //printf("%i ",val); if (val>=maxiterations1) { uValue=r*12; //for example use r for material volData.setVoxelAt(x, y, z, uValue); } } } } } ... createMandelbulb(volData); ... Example size 128 
Author:  David Williams [ Mon Jan 23, 2012 4:36 pm ] 
Post subject:  Re: mandelbulb 
Very nice! Reminds me of some work I did testing the Menger Sponge, though I didn't make any screenshots of that. Fractals are great for generating data to use with PolyVox. It would be interesting to have a whole game world built in this way... 
Author:  zprg [ Fri Nov 02, 2012 3:25 pm ] 
Post subject:  Re: mandelbulb 
now i tried mandelbulb instead of cubicsurfaceextractor with surfaceextractor and the smooth look has its own charme: 
Author:  milliams [ Fri Nov 02, 2012 4:05 pm ] 
Post subject:  Re: mandelbulb 
Very nice. This would make a very good stress test of the PolyVox surface extractors for benchmarking. 
Author:  David Williams [ Sat Nov 03, 2012 8:10 am ] 
Post subject:  Re: mandelbulb 
Yep, I like it! I also discovered the Mandelbox recently and thought that would make a good test for just how far we can push PolyVox. I'll try to give it a go once the Gameplay3D integration has come a bit further. 
Author:  David Williams [ Sun Mar 17, 2013 8:14 pm ] 
Post subject:  Re: mandelbulb 
As you might have seen in this thread I've finally made a version of the Mandelbulb myself now. I haven't actually tried loading it into PolyVox/Cubiquity yet but I already have a question. How did you choose what colour each voxel should be? For each voxel I am storing the number of iterations which were required for the fractal to converge (so it's a greyscale image). I can imagine this could be mapped to a colour gradient which would look great if you cut the volume in half, but I'm not sure it helps if you view the volume from the outside? I assume you had to choose a threshold for how many iterations represented a solid and how many represented empty space. Let's say the threshold is 100... doesn't that mean that all voxels on the surface will have a value of 100 and so will all be the same colour? Maybe you used a different approach such as computing the distance from the centre of the fractal to the voxel, and then using this to determine the colour? 
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