Warp <war### [at] tagpovrayorg> wrote:
> Woody <nomail@nomail> wrote:
> > [-- text/plain, encoding 8bit, charset: iso-8859-1, 117 lines --]
>
> > Warp <war### [at] tagpovrayorg> wrote:
> > > Woody <nomail@nomail> wrote:
> > > > What do I need to do to modify the program code shown below, so that the first
> > > > line of the data file, instead of taking 3 parameters (Size of each
dimension),
> > > > takes 4 arguments (Size of each of the three dimensins + bit resolution type).
> > > > Where the bit resolution type is 8, 16 or 32bit.
> > >
> > >   It requires quite some modifications because writing the larger integrals
> > > is slightly more complicated, but this should do it:
> > >
> > > //---------------------------------------------------------------------
> > > #include <iostream>
> > > #include <fstream>
> > > #include <vector>
> > > #include <string>
> > > #include <cstdio>
> > > #include <cassert>
> > >
> > > template<typename Int_t>
> > > void writeIntValue(Int_t value, std::ostream& os)
> > > {
> > >     for(unsigned byteInd = sizeof(Int_t); byteInd-- > 0;)
> > >         os << (unsigned char)((value >> (byteInd * 8)) & 0xFF);
> > > }
> > >
> > > template<typename Int_t>
> > > void createDF3(std::istream& is, std::ostream& os,
> > >                size_t xSize, size_t ySize, size_t zSize)
> > > {
> > >     std::vector<Int_t> data(xSize*ySize*zSize, 0);
> > >
> > >     while(true)
> > >     {
> > >         size_t x, y, z, value;
> > >         is >> x >> y >> z >> value;
> > >         if(!is) break;
> > >         const size_t ind = x + y*xSize + z*xSize*ySize;
> > >         if(ind < data.size())
> > >             data[ind] = Int_t(value);
> > >     }
> > >
> > >     for(size_t i = 0; i < data.size(); ++i)
> > >         writeIntValue(data[i], os);
> > > }
> > >
> > > int main(int argc, char* argv[])
> > > {
> > >     // Limit the size of the df3 dimensions (safeguard against invalid input).
> > >     // Maximum df3 size will be SIZE_LIMIT*SIZE_LIMIT*SIZE_LIMIT.
> > >     const size_t SIZE_LIMIT = 256;
> > >
> > >     typedef unsigned char Int8_t;
> > >     typedef unsigned short Int16_t;
> > >     typedef unsigned int Int32_t;
> > >     assert(sizeof(Int16_t) == 2);
> > >     assert(sizeof(Int32_t) == 4);
> > >
> > >     if(argc < 2)
> > >     {
> > >         std::cout << "Usage: " << argv[0] << " <files>\n";
> > >         return 0;
> > >     }
> > >
> > >     for(int i = 1; i < argc; ++i) // for each input file
> > >     {
> > >         std::ifstream is(argv[i]);
> > >         if(!is.good())
> > >         {
> > >             std::cerr << "Couldn't open ";
> > >             std::perror(argv[i]);
> > >             continue;
> > >         }
> > >
> > >         size_t xSize, ySize, zSize, bits;
> > >         is >> xSize >> ySize >> zSize >> bits;
> > >         if(xSize > SIZE_LIMIT || ySize > SIZE_LIMIT || zSize > SIZE_LIMIT ||
> > >            (bits != 8 && bits != 16 && bits != 32))
> > >         {
> > >             std::cout << "Skipping " << argv[i] << " (invalid input)\n";
> > >             continue;
> > >         }
> > >
> > >         std::string filename = argv[i];
> > >         size_t ind = filename.find_last_of('.');
> > >         if(ind != filename.npos) filename.resize(ind);
> > >         filename += ".df3";
> > >         std::ofstream os(filename.c_str(), std::ios::binary);
> > >
> > >         char header[6];
> > >         header[0] = xSize/256; header[1] = xSize%256;
> > >         header[2] = ySize/256; header[3] = ySize%256;
> > >         header[4] = zSize/256; header[5] = zSize%256;
> > >         os.write(header, 6);
> > >
> > >         switch(bits)
> > >         {
> > >           case 8: createDF3<Int8_t>(is, os, xSize, ySize, zSize); break;
> > >           case 16: createDF3<Int16_t>(is, os, xSize, ySize, zSize); break;
> > >           case 32: createDF3<Int32_t>(is, os, xSize, ySize, zSize); break;
> > >         }
> > >
> > >         std::cout << argv[i] << " -> " << filename << std::endl;
> > >     }
> > > }
> > > //---------------------------------------------------------------------
> > >
> > > --
> > >                                                           - Warp
>
> > So does this always use 255 as the max voxel value regardless of the bit
> > resolution?
>
> > How does 255 (besides being 256 minus 1) relate to the bit resolution?
>
>   Where do you see a 255 in the program?
>
>   The maximum value for each voxel is dependent on the bit size. If you
> are eg. using 16 bits, the maximum value is 65535.
>
> --
>                                                           - Warp

I suppose I was seeing 255 from the sample I posted at
http://news.povray.org/4799ff49%40news.povray.org and was thinking that 255 was
the maximum.

Thanks Again for your help. :)


-Jeff

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