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/* GIMP - The GNU Image Manipulation Program
* Copyright (C) 1995 Spencer Kimball and Peter Mattis
*
* kernelgen -- Copyright (C) 2000 Sven Neumann <sven@gimp.org>
*
* Simple hack to create brush subsampling kernels. If you want to
* play with it, change some of the #defines at the top and copy
* the output to app/paint/gimpbrushcore-kernels.h.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <math.h>
#include <stdio.h>
#include <string.h>
#define STEPS 64
#define KERNEL_WIDTH 3 /* changing these makes no sense */
#define KERNEL_HEIGHT 3 /* changing these makes no sense */
#define KERNEL_SUM 256
#define SUBSAMPLE 4
#define THRESHOLD 0.25 /* try to change this one */
#define SQR(x) ((x) * (x))
static void
create_kernel (double x,
double y)
{
double value[KERNEL_WIDTH][KERNEL_HEIGHT];
double dist_x;
double dist_y;
double sum;
double w;
int i, j;
memset (value, 0, KERNEL_WIDTH * KERNEL_HEIGHT * sizeof (double));
sum = 0.0;
x += 1.0;
y += 1.0;
for (j = 0; j < STEPS * KERNEL_HEIGHT; j++)
{
dist_y = y - (((double)j + 0.5) / (double)STEPS);
for (i = 0; i < STEPS * KERNEL_WIDTH; i++)
{
dist_x = x - (((double) i + 0.5) / (double) STEPS);
/* I've tried to use a gauss function here instead of a
threshold, but the result was not that impressive. */
w = (SQR (dist_x) + SQR (dist_y)) < THRESHOLD ? 1.0 : 0.0;
value[i / STEPS][j / STEPS] += w;
sum += w;
}
}
for (j = 0; j < KERNEL_HEIGHT; j++)
{
for (i = 0; i < KERNEL_WIDTH; i++)
{
w = (double) KERNEL_SUM * value[i][j] / sum;
printf (" %3d,", (int) (w + 0.5));
}
}
}
int
main (int argc,
char **argv)
{
int i, j;
double x, y;
printf ("/* gimpbrushcore-kernels.h\n"
" *\n"
" * This file was generated using kernelgen as found in the tools dir.\n");
printf (" * (threshold = %g)\n", THRESHOLD);
printf (" */\n\n");
printf ("#ifndef __GIMP_BRUSH_CORE_KERNELS_H__\n");
printf ("#define __GIMP_BRUSH_CORE_KERNELS_H__\n\n");
printf ("#define KERNEL_WIDTH %d\n", KERNEL_WIDTH);
printf ("#define KERNEL_HEIGHT %d\n", KERNEL_HEIGHT);
printf ("#define KERNEL_SUBSAMPLE %d\n", SUBSAMPLE);
printf ("#define KERNEL_SUM %d\n", KERNEL_SUM);
printf ("\n\n");
printf ("/* Brush pixel subsampling kernels */\n");
printf ("static const int subsample[%d][%d][%d] =\n{\n",
SUBSAMPLE + 1, SUBSAMPLE + 1, KERNEL_WIDTH * KERNEL_HEIGHT);
for (j = 0; j <= SUBSAMPLE; j++)
{
y = (double) j / (double) SUBSAMPLE;
printf (" {\n");
for (i = 0; i <= SUBSAMPLE; i++)
{
x = (double) i / (double) SUBSAMPLE;
printf (" {");
create_kernel (x, y);
printf (" }%s", i < SUBSAMPLE ? ",\n" : "\n");
}
printf (" }%s", j < SUBSAMPLE ? ",\n" : "\n");
}
printf ("};\n\n");
printf ("#endif /* __GIMP_BRUSH_CORE_KERNELS_H__ */\n");
return 0;
}
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