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/* pgmramp.c - generate a grayscale ramp
**
** Copyright (C) 1989 by Jef Poskanzer.
**
** Permission to use, copy, modify, and distribute this software and its
** documentation for any purpose and without fee is hereby granted, provided
** that the above copyright notice appear in all copies and that both that
** copyright notice and this permission notice appear in supporting
** documentation. This software is provided "as is" without express or
** implied warranty.
*/
#include "pgm.h"
int
main( argc, argv )
int argc;
char *argv[];
{
gray *grayrow;
register gray *gP;
int rows, cols, rowso2, colso2, row;
register int col;
int ramptype;
#define RT_LR 1
#define RT_TB 2
#define RT_RECT 3
#define RT_ELLIP 4
char *usage = "-lr|-tb|-rectangle|-ellipse <width> <height>";
pgm_init( &argc, argv );
if ( argc != 4 )
pm_usage( usage );
if ( pm_keymatch( argv[1], "-lr", 2 ) )
ramptype = RT_LR;
else if ( pm_keymatch( argv[1], "-tb", 2 ) )
ramptype = RT_TB;
else if ( pm_keymatch( argv[1], "-rectangle", 2 ) )
ramptype = RT_RECT;
else if ( pm_keymatch( argv[1], "-ellipse", 2 ) )
ramptype = RT_ELLIP;
else
pm_usage( usage );
if ( sscanf( argv[2], "%d", &cols ) != 1 )
pm_usage( usage );
if ( sscanf( argv[3], "%d", &rows ) != 1 )
pm_usage( usage );
colso2 = cols / 2;
rowso2 = rows / 2;
pgm_writepgminit( stdout, cols, rows, 255, 0 );
grayrow = pgm_allocrow( cols );
for ( row = 0; row < rows; ++row )
{
for ( col = 0, gP = grayrow; col < cols; ++col, ++gP )
{
switch ( ramptype )
{
case RT_LR:
*gP = col * 255 / ((cols == 1) ? 1 : (cols - 1));
break;
case RT_TB:
*gP = row * 255 / ((rows == 1) ? 1 : (rows - 1));
break;
case RT_RECT:
{
float r, c;
r = abs( rowso2 - row ) / (float) rowso2;
c = abs( colso2 - col ) / (float) colso2;
*gP = 255 - ( r + c ) / 2.0 * 255;
}
break;
case RT_ELLIP:
{
float r, c, v;
r = abs( rowso2 - row ) / (float) rowso2;
c = abs( colso2 - col ) / (float) colso2;
v = r * r + c * c;
if ( v < 0.0 ) v = 0.0;
else if ( v > 1.0 ) v = 1.0;
*gP = 255 - v * 255;
}
break;
default:
pm_error( "can't happen" );
}
}
pgm_writepgmrow( stdout, grayrow, cols, 255, 0 );
}
pm_close( stdout );
exit( 0 );
}
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