133 lines
3.9 KiB
C
133 lines
3.9 KiB
C
/* PIKA - Photo and Image Kooker Application
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* a rebranding of The GNU Image Manipulation Program (created with heckimp)
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* A derived work which may be trivial. However, any changes may be (C)2023 by Aldercone Studio
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*
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* Original copyright, applying to most contents (license remains unchanged):
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* Copyright (C) 1995 Spencer Kimball and Peter Mattis
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*
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* kernelgen -- Copyright (C) 2000 Sven Neumann <sven@gimp.org>
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*
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* Simple hack to create brush subsampling kernels. If you want to
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* play with it, change some of the #defines at the top and copy
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* the output to app/paint/pikabrushcore-kernels.h.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#include <math.h>
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#include <stdio.h>
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#include <string.h>
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#define STEPS 64
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#define KERNEL_WIDTH 3 /* changing these makes no sense */
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#define KERNEL_HEIGHT 3 /* changing these makes no sense */
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#define KERNEL_SUM 256
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#define SUBSAMPLE 4
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#define THRESHOLD 0.25 /* try to change this one */
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#define SQR(x) ((x) * (x))
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static void
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create_kernel (double x,
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double y)
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{
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double value[KERNEL_WIDTH][KERNEL_HEIGHT];
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double dist_x;
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double dist_y;
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double sum;
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double w;
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int i, j;
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memset (value, 0, KERNEL_WIDTH * KERNEL_HEIGHT * sizeof (double));
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sum = 0.0;
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x += 1.0;
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y += 1.0;
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for (j = 0; j < STEPS * KERNEL_HEIGHT; j++)
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{
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dist_y = y - (((double)j + 0.5) / (double)STEPS);
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for (i = 0; i < STEPS * KERNEL_WIDTH; i++)
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{
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dist_x = x - (((double) i + 0.5) / (double) STEPS);
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/* I've tried to use a gauss function here instead of a
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threshold, but the result was not that impressive. */
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w = (SQR (dist_x) + SQR (dist_y)) < THRESHOLD ? 1.0 : 0.0;
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value[i / STEPS][j / STEPS] += w;
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sum += w;
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}
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}
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for (j = 0; j < KERNEL_HEIGHT; j++)
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{
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for (i = 0; i < KERNEL_WIDTH; i++)
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{
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w = (double) KERNEL_SUM * value[i][j] / sum;
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printf (" %3d,", (int) (w + 0.5));
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}
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}
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}
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int
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main (int argc,
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char **argv)
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{
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int i, j;
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double x, y;
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printf ("/* pikabrushcore-kernels.h\n"
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" *\n"
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" * This file was generated using kernelgen as found in the tools dir.\n");
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printf (" * (threshold = %g)\n", THRESHOLD);
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printf (" */\n\n");
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printf ("#ifndef __PIKA_BRUSH_CORE_KERNELS_H__\n");
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printf ("#define __PIKA_BRUSH_CORE_KERNELS_H__\n\n");
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printf ("#define KERNEL_WIDTH %d\n", KERNEL_WIDTH);
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printf ("#define KERNEL_HEIGHT %d\n", KERNEL_HEIGHT);
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printf ("#define KERNEL_SUBSAMPLE %d\n", SUBSAMPLE);
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printf ("#define KERNEL_SUM %d\n", KERNEL_SUM);
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printf ("\n\n");
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printf ("/* Brush pixel subsampling kernels */\n");
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printf ("static const int subsample[%d][%d][%d] =\n{\n",
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SUBSAMPLE + 1, SUBSAMPLE + 1, KERNEL_WIDTH * KERNEL_HEIGHT);
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for (j = 0; j <= SUBSAMPLE; j++)
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{
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y = (double) j / (double) SUBSAMPLE;
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printf (" {\n");
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for (i = 0; i <= SUBSAMPLE; i++)
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{
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x = (double) i / (double) SUBSAMPLE;
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printf (" {");
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create_kernel (x, y);
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printf (" }%s", i < SUBSAMPLE ? ",\n" : "\n");
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}
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printf (" }%s", j < SUBSAMPLE ? ",\n" : "\n");
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}
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printf ("};\n\n");
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printf ("#endif /* __PIKA_BRUSH_CORE_KERNELS_H__ */\n");
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return 0;
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}
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