write_pgm.h

// write_pgm.h
// (c)2019 Bram Stolk

#if 0
static void write_pgm( FILE*f, scalar* im, int sz )
{
	const size_t datasz = (size_t) ( sz * sz );
	unsigned char* data = ( unsigned char* ) malloc( datasz );
	scalar* reader = im;
	unsigned char* writer = data;
	for ( int y=0; y<sz; ++y )
		for ( int x=0; x<sz; ++x )
		{
			const int v = (int) ( 255.99999f * (*reader++) );
			*writer++ = (unsigned char) v;
		}
	fprintf( f, "P5\n%d %d\n255\n", sz, sz );
	fwrite( data, datasz, 1, f );
	free( data );
}
#endif

static unsigned char viridis[256][3] = 
{
  68,1,84,
  68,2,85,
  68,3,87,
  69,5,88,
  69,6,90,
  69,8,91,
  70,9,92,
  70,11,94,
  70,12,95,
  70,14,97,
  71,15,98,
  71,17,99,
  71,18,101,
  71,20,102,
  71,21,103,
  71,22,105,
  71,24,106,
  72,25,107,
  72,26,108,
  72,28,110,
  72,29,111,
  72,30,112,
  72,32,113,
  72,33,114,
  72,34,115,
  72,35,116,
  71,37,117,
  71,38,118,
  71,39,119,
  71,40,120,
  71,42,121,
  71,43,122,
  71,44,123,
  70,45,124,
  70,47,124,
  70,48,125,
  70,49,126,
  69,50,127,
  69,52,127,
  69,53,128,
  69,54,129,
  68,55,129,
  68,57,130,
  67,58,131,
  67,59,131,
  67,60,132,
  66,61,132,
  66,62,133,
  66,64,133,
  65,65,134,
  65,66,134,
  64,67,135,
  64,68,135,
  63,69,135,
  63,71,136,
  62,72,136,
  62,73,137,
  61,74,137,
  61,75,137,
  61,76,137,
  60,77,138,
  60,78,138,
  59,80,138,
  59,81,138,
  58,82,139,
  58,83,139,
  57,84,139,
  57,85,139,
  56,86,139,
  56,87,140,
  55,88,140,
  55,89,140,
  54,90,140,
  54,91,140,
  53,92,140,
  53,93,140,
  52,94,141,
  52,95,141,
  51,96,141,
  51,97,141,
  50,98,141,
  50,99,141,
  49,100,141,
  49,101,141,
  49,102,141,
  48,103,141,
  48,104,141,
  47,105,141,
  47,106,141,
  46,107,142,
  46,108,142,
  46,109,142,
  45,110,142,
  45,111,142,
  44,112,142,
  44,113,142,
  44,114,142,
  43,115,142,
  43,116,142,
  42,117,142,
  42,118,142,
  42,119,142,
  41,120,142,
  41,121,142,
  40,122,142,
  40,122,142,
  40,123,142,
  39,124,142,
  39,125,142,
  39,126,142,
  38,127,142,
  38,128,142,
  38,129,142,
  37,130,142,
  37,131,141,
  36,132,141,
  36,133,141,
  36,134,141,
  35,135,141,
  35,136,141,
  35,137,141,
  34,137,141,
  34,138,141,
  34,139,141,
  33,140,141,
  33,141,140,
  33,142,140,
  32,143,140,
  32,144,140,
  32,145,140,
  31,146,140,
  31,147,139,
  31,148,139,
  31,149,139,
  31,150,139,
  30,151,138,
  30,152,138,
  30,153,138,
  30,153,138,
  30,154,137,
  30,155,137,
  30,156,137,
  30,157,136,
  30,158,136,
  30,159,136,
  30,160,135,
  31,161,135,
  31,162,134,
  31,163,134,
  32,164,133,
  32,165,133,
  33,166,133,
  33,167,132,
  34,167,132,
  35,168,131,
  35,169,130,
  36,170,130,
  37,171,129,
  38,172,129,
  39,173,128,
  40,174,127,
  41,175,127,
  42,176,126,
  43,177,125,
  44,177,125,
  46,178,124,
  47,179,123,
  48,180,122,
  50,181,122,
  51,182,121,
  53,183,120,
  54,184,119,
  56,185,118,
  57,185,118,
  59,186,117,
  61,187,116,
  62,188,115,
  64,189,114,
  66,190,113,
  68,190,112,
  69,191,111,
  71,192,110,
  73,193,109,
  75,194,108,
  77,194,107,
  79,195,105,
  81,196,104,
  83,197,103,
  85,198,102,
  87,198,101,
  89,199,100,
  91,200,98,
  94,201,97,
  96,201,96,
  98,202,95,
  100,203,93,
  103,204,92,
  105,204,91,
  107,205,89,
  109,206,88,
  112,206,86,
  114,207,85,
  116,208,84,
  119,208,82,
  121,209,81,
  124,210,79,
  126,210,78,
  129,211,76,
  131,211,75,
  134,212,73,
  136,213,71,
  139,213,70,
  141,214,68,
  144,214,67,
  146,215,65,
  149,215,63,
  151,216,62,
  154,216,60,
  157,217,58,
  159,217,56,
  162,218,55,
  165,218,53,
  167,219,51,
  170,219,50,
  173,220,48,
  175,220,46,
  178,221,44,
  181,221,43,
  183,221,41,
  186,222,39,
  189,222,38,
  191,223,36,
  194,223,34,
  197,223,33,
  199,224,31,
  202,224,30,
  205,224,29,
  207,225,28,
  210,225,27,
  212,225,26,
  215,226,25,
  218,226,24,
  220,226,24,
  223,227,24,
  225,227,24,
  228,227,24,
  231,228,25,
  233,228,25,
  236,228,26,
  238,229,27,
  241,229,28,
  243,229,30,
  246,230,31,
  248,230,33,
  250,230,34,
  253,231,36,
};


static void write_ppm( FILE* f, scalar* im, int sz )
{
	const size_t datasz = (size_t) ( sz * sz * 3 );
	unsigned char* data = ( unsigned char* ) malloc( datasz );
	scalar* reader = im;
	unsigned char* writer = data;
	for ( int y=0; y<sz; ++y )
		for ( int x=0; x<sz; ++x )
		{
			const int i = (int) ( 255.99999f * (*reader++) );
			unsigned char r = viridis[i][0];
			unsigned char g = viridis[i][1];
			unsigned char b = viridis[i][2];
			*writer++ = (unsigned char) r;
			*writer++ = (unsigned char) g;
			*writer++ = (unsigned char) b;
		}
	fprintf( f, "P6\n%d %d\n255\n", sz, sz );
	fwrite( data, datasz, 1, f );
	free( data );
}



static void write_ppm_3channel( FILE* f, scalar* im, int sz )
{
	const size_t datasz = (size_t) ( sz * sz * 3 );
	unsigned char* data = ( unsigned char* ) malloc( datasz );
	scalar* reader = im;
	unsigned char* writer = data;
	for ( int y=0; y<sz; ++y )
		for ( int x=0; x<sz; ++x )
		{
			const int r = (int) ( 255.99999f * (*reader++) );
			const int g = (int) ( 255.99999f * (*reader++) );
			const int b = (int) ( 255.99999f * (*reader++) );
			*writer++ = (unsigned char) r;
			*writer++ = (unsigned char) g;
			*writer++ = (unsigned char) b;
		}
	fprintf( f, "P6\n%d %d\n255\n", sz, sz );
	fwrite( data, datasz, 1, f );
	free( data );
}


static void write_ppm_3channel_int( FILE* f, unsigned char* data, int sz )
{
	fprintf( f, "P6\n%d %d\n255\n", sz, sz );
	const int datasz = sz*sz*3;
	fwrite( data, datasz, 1, f );
}