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glfractal.c
executable file
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glfractal.c
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/* MIT license; Copyright (c) 2012 by Attractive Chaos <attractor@live.co.uk>
gcc -Wall -O2 glfractal.c -o glfractal -framework GLUT -framework OpenGL # Mac OS X
gcc -Wall -O2 glfractal.c -o glfractal -lglut -lGL -lGLU -lX11 -lm # Linux (not tried)
With reference to:
http://www.postulate.org/attractor/attractor.zip (a good one, but dead unfortunately)
http://nuclear.mutantstargoat.com/articles/sdr_fract/
http://rosettacode.org/wiki/Mandelbrot_set#C
*/
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <ctype.h>
#ifdef __APPLE__
#include <GLUT/glut.h>
#else
#include <gl/glut.h>
#endif
typedef struct {
unsigned char r, g, b;
} rgbcolor_t;
static rgbcolor_t g_palette_neon[256], g_palette_blues[256], g_palette_custom[256]; /* defined at the end of the file */
static struct {
int width, height, max_iter, ns, np, pal_id;
double xmin, xmax, ymin, ymax;
unsigned char *buf;
rgbcolor_t *palette[3];
} g_data = { 800, 600, 256, 1, 1, 0, -2, 1.2, -1.2, 1.2, NULL, {g_palette_neon, g_palette_blues, NULL} }; /* NB: 800/600=(1.2+2)/(1.2+1.2)=4/3 */
/********************
* Mandelbrot plane *
********************/
void glf_mbrot_simple(unsigned char *buf, int max_iter, int w, int h, double xmin, double xmax, double ymin, double ymax, const rgbcolor_t palette[256])
{
int i, j, k;
double w1, h1, x0, y0;
rgbcolor_t *p = (rgbcolor_t*)buf;
w1 = 1. / w; h1 = 1. / h;
for (j = 0; j < h; ++j) {
y0 = ymin + (ymax - ymin) * j * h1;
for (i = 0; i < w; ++i) {
double x = x0 = xmin + (xmax - xmin) * i * w1, y = y0;
for (k = 0; k < max_iter; ++k) {
double z = x * y;
x *= x; y *= y;
if (x + y >= 4) break;
x = x - y + x0;
y = z + z + y0;
}
*p++ = palette[k&0xff];
}
}
}
/**************************
* GLUT related functions *
**************************/
static void cb_draw(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glf_mbrot_simple(g_data.buf, g_data.max_iter, g_data.width, g_data.height, g_data.xmin, g_data.xmax, g_data.ymin, g_data.ymax, g_data.palette[g_data.pal_id]);
glDrawPixels(g_data.width, g_data.height, GL_RGB, GL_UNSIGNED_BYTE, g_data.buf);
glutSwapBuffers();
}
static void cb_key(unsigned char key, int x, int y)
{
if (key == 27 || key == 'q' || key == 'Q') {
free(g_data.buf);
exit(0);
} else if (isdigit(key)) {
if (key == '0') key = 10 + '0';
g_data.max_iter = (int)(key - '0') << 8;
fprintf(stderr, "(MM) Max iteration: %d\n", g_data.max_iter);
cb_draw();
} else if (key == 'd' || key == 'D') {
unsigned i, x = g_data.max_iter;
unsigned char *p;
double f[4];
f[0] = g_data.xmin; f[1] = g_data.xmax; f[2] = g_data.ymin; f[3] = g_data.ymax;
for (i = 0, p = (unsigned char*)&x; i < 4; ++i) fprintf(stderr, "%.2x", p[i]);
for (i = 0, p = (unsigned char*)f; i < 32; ++i) fprintf(stderr, "%.2x", p[i]);
fprintf(stderr, "\n");
} else if (key == 's' || key == 'S') {
char fn[32];
FILE *fp;
sprintf(fn, "screen%.3d.ppm", g_data.np++);
if ((fp = fopen(fn, "wb")) != NULL) {
fprintf(fp, "P6\n%d %d\n255\n", g_data.width, g_data.height);
fwrite(g_data.buf, 1, 3 * g_data.width * g_data.height, fp);
fclose(fp);
fprintf(stderr, "(MM) Save screenshot to file '%s'.\n", fn);
}
} else if (key == '>' || key == '.') {
g_data.max_iter += 256;
cb_draw();
fprintf(stderr, "(MM) Max iteration: %d\n", g_data.max_iter);
} else if (key == '<' || key == ',') {
if (g_data.max_iter >= 512) g_data.max_iter -= 256;
cb_draw();
fprintf(stderr, "(MM) Max iteration: %d\n", g_data.max_iter);
} else if (key == 'p' || key == 'P') {
g_data.pal_id = (g_data.pal_id + 1) % 3;
if (g_data.palette[g_data.pal_id] == NULL)
g_data.pal_id = (g_data.pal_id + 1) % 3;
cb_draw();
}
}
static void cb_mouse(int bn, int state, int x, int y)
{
if (state == GLUT_UP && (bn == GLUT_LEFT_BUTTON || bn == GLUT_RIGHT_BUTTON)) {
double xc = g_data.xmin + (g_data.xmax - g_data.xmin) * x / g_data.width;
double yc = g_data.ymin + (g_data.ymax - g_data.ymin) * (g_data.height - y) / g_data.height;
double xstep = (g_data.xmax - g_data.xmin) * (bn == 0? .5 : 2.) * .5;
double ystep = (g_data.ymax - g_data.ymin) * (bn == 0? .5 : 2.) * .5;
g_data.xmin = xc - xstep, g_data.xmax = xc + xstep;
g_data.ymin = yc - ystep, g_data.ymax = yc + ystep;
cb_draw();
}
}
/*****************
* Main function *
*****************/
int main(int argc, char *argv[])
{
/* parse command-line options */
int c, is_full = 0;
double yran, yc;
fprintf(stderr, "\nKey bindings:\n\n");
fprintf(stderr, " LeftClick zoom in by 2X\n");
fprintf(stderr, " RightClick zoom out by 2X\n");
fprintf(stderr, " < or , decrease max iteration by 256\n");
fprintf(stderr, " > or . increase max iteration by 256\n");
fprintf(stderr, " NUMBER change max iteration to 256*NUMBER\n");
fprintf(stderr, " p or P change to the next palette\n");
fprintf(stderr, " d or D dump data to 'dataNNN.dat'\n");
fprintf(stderr, " s or S save screenshot to 'screenNNN.ppm'\n");
fprintf(stderr, " ESC or q or Q exit\n\n");
fprintf(stderr, "Command line options:\n\n");
fprintf(stderr, " -i STR hex string dumped by 'd' or 'D' [null]\n");
fprintf(stderr, " -m FILE palette file [null]\n");
fprintf(stderr, " -w INT image width in pixel [800]\n");
fprintf(stderr, " -h INT image height in pixel [600]\n");
fprintf(stderr, " -f full screen mode\n\n");
while ((c = getopt(argc, argv, "fw:h:i:m:")) >= 0) {
if (c == 'w') g_data.width = (atoi(optarg) + 3) / 4 * 4;
else if (c == 'h') g_data.height = (atoi(optarg) + 3) / 4 * 4;
else if (c == 'f') is_full = 1;
else if (c == 'i') {
unsigned i, x;
double f[4];
unsigned char r[72], *p;
strncpy((char*)r, optarg, 72);
for (i = 0; i < 72; ++i)
r[i] -= (r[i] >= '0' && r[i] <= '9')? '0' : (r[i] >= 'a' && r[i] <= 'f'? 'a' : 'A') - 10;
for (i = 0, p = (unsigned char*)&x; i < 4; ++i) p[i] = r[i<<1]<<4 | r[i<<1|1];
g_data.max_iter = x;
for (i = 4, p = (unsigned char*)f; i < 36; ++i) p[i - 4] = r[i<<1]<<4 | r[i<<1|1];
g_data.xmin = f[0]; g_data.xmax = f[1]; g_data.ymin = f[2]; g_data.ymax = f[3];
} else if (c == 'm') {
FILE *fp;
int i, tmp[3];
if ((fp = fopen(optarg, "r")) != NULL) {
for (i = 0; i < 256; ++i) { /* FIXME: improve error checking */
if (fscanf(fp, "%d%d%d", &tmp[0], &tmp[1], &tmp[2]) != 3) {
fprintf(stderr, "(WW) Invalid palette at line %d\n", i + 1);
break;
}
g_palette_custom[i].r = tmp[0]; g_palette_custom[i].g = tmp[1]; g_palette_custom[i].b = tmp[2];
}
fclose(fp);
if (i == 256) g_data.palette[2] = g_palette_custom, g_data.pal_id = 2; /* default to the custom palette */
} else fprintf(stderr, "(WW) Fail to read map file '%s'. Continue anyway.\n", optarg);
}
}
g_data.buf = malloc(3 * g_data.width * g_data.height);
/* Scale the Y axis to keep the right ratio */
yran = (g_data.xmax - g_data.xmin) * g_data.height / g_data.width;
yc = .5 * (g_data.ymax + g_data.ymin);
g_data.ymax = yc + .5 * yran; g_data.ymin = yc - .5 * yran;
/* Initialize OpenGL */
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGB);
glutInitWindowSize(g_data.width, g_data.height);
if (is_full) {
char mode[64];
sprintf(mode, "%dx%d", g_data.width, g_data.height);
glutGameModeString(mode);
glutEnterGameMode();
} else glutCreateWindow("Mandelbrot Viewer");
glutDisplayFunc(cb_draw);
glutKeyboardFunc(cb_key);
glutMouseFunc(cb_mouse);
glDisable(GL_DEPTH_TEST);
glutMainLoop();
return 0;
}
/**********************
* Predefined palette *
**********************/
static rgbcolor_t g_palette_neon[256] = {
{ 0, 0, 0},{ 0, 0, 0},{ 8, 0, 0},{ 16, 4, 4},{ 24, 4, 8},{ 32, 8, 12},{ 40, 12, 16},{ 48, 12, 20},
{ 56, 16, 24},{ 64, 20, 28},{ 72, 20, 32},{ 80, 24, 36},{ 88, 28, 40},{ 96, 28, 44},{104, 32, 48},{112, 36, 52},
{120, 36, 56},{128, 40, 60},{136, 40, 64},{144, 44, 68},{152, 48, 72},{160, 48, 76},{168, 52, 80},{176, 56, 84},
{184, 56, 88},{192, 60, 92},{200, 64, 96},{208, 64,100},{216, 68,104},{224, 72,108},{232, 72,112},{240, 76,116},
{252, 80,120},{248, 80,120},{240, 76,116},{232, 76,112},{224, 72,108},{216, 68,104},{208, 68,100},{200, 64, 96},
{192, 60, 92},{184, 60, 88},{176, 56, 84},{168, 56, 80},{160, 52, 76},{152, 48, 72},{144, 48, 68},{136, 44, 64},
{128, 40, 60},{120, 40, 60},{112, 36, 56},{104, 36, 52},{ 96, 32, 48},{ 88, 28, 44},{ 80, 28, 40},{ 72, 24, 36},
{ 64, 20, 32},{ 56, 20, 28},{ 48, 16, 24},{ 40, 16, 20},{ 32, 12, 16},{ 24, 8, 12},{ 16, 8, 8},{ 8, 4, 4},
{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},
{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},
{ 0, 0, 0},{ 0, 4, 0},{ 0, 12, 0},{ 0, 20, 0},{ 0, 28, 0},{ 0, 36, 0},{ 0, 44, 0},{ 0, 52, 0},
{ 0, 60, 0},{ 0, 68, 0},{ 0, 76, 0},{ 0, 84, 0},{ 0, 92, 0},{ 0,100, 0},{ 0,108, 0},{ 0,116, 0},
{ 0,124, 0},{ 0,132, 0},{ 0,140, 0},{ 0,148, 0},{ 0,156, 0},{ 0,164, 0},{ 0,172, 0},{ 0,180, 0},
{ 0,188, 0},{ 0,196, 0},{ 0,204, 0},{ 0,212, 0},{ 0,220, 0},{ 0,228, 0},{ 0,236, 0},{ 0,244, 0},
{ 0,252, 0},{ 0,248, 0},{ 0,240, 0},{ 0,232, 0},{ 0,224, 0},{ 0,216, 0},{ 0,208, 0},{ 0,200, 0},
{ 0,192, 0},{ 0,184, 0},{ 0,176, 0},{ 0,168, 0},{ 0,160, 0},{ 0,152, 0},{ 0,144, 0},{ 0,136, 0},
{ 0,128, 0},{ 0,120, 0},{ 0,112, 0},{ 0,104, 0},{ 0, 96, 0},{ 0, 88, 0},{ 0, 80, 0},{ 0, 72, 0},
{ 0, 64, 0},{ 0, 56, 0},{ 0, 48, 0},{ 0, 40, 0},{ 0, 32, 0},{ 0, 24, 0},{ 0, 16, 0},{ 0, 8, 0},
{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},
{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},
{ 0, 0, 0},{ 4, 4, 0},{ 12, 12, 0},{ 20, 20, 0},{ 28, 28, 0},{ 36, 36, 0},{ 44, 44, 0},{ 52, 52, 0},
{ 60, 60, 0},{ 68, 68, 0},{ 76, 76, 0},{ 84, 84, 0},{ 92, 92, 0},{100,100, 0},{108,108, 0},{116,116, 0},
{124,124, 0},{132,132, 0},{140,140, 0},{148,148, 0},{156,156, 0},{164,164, 0},{172,172, 0},{180,180, 0},
{188,188, 0},{196,196, 0},{204,204, 0},{212,212, 0},{220,220, 0},{228,228, 0},{236,236, 0},{244,244, 0},
{252,252, 0},{248,248, 0},{240,240, 0},{232,232, 0},{224,224, 0},{216,216, 0},{208,208, 0},{200,200, 0},
{192,192, 0},{184,184, 0},{176,176, 0},{168,168, 0},{160,160, 0},{152,152, 0},{144,144, 0},{136,136, 0},
{128,128, 0},{120,120, 0},{112,112, 0},{104,104, 0},{ 96, 96, 0},{ 88, 88, 0},{ 80, 80, 0},{ 72, 72, 0},
{ 64, 64, 0},{ 56, 56, 0},{ 48, 48, 0},{ 40, 40, 0},{ 32, 32, 0},{ 24, 24, 0},{ 16, 16, 0},{ 8, 8, 0},
{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},
{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},
{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},
{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 0}
};
static rgbcolor_t g_palette_blues[256] = {
{ 0, 0, 0},{ 0, 0, 0},{ 0, 0, 4},{ 0, 0, 12},{ 0, 0, 16},{ 0, 0, 24},{ 0, 0, 32},{ 0, 0, 36},
{ 0, 0, 44},{ 0, 0, 48},{ 0, 0, 56},{ 0, 0, 64},{ 0, 0, 68},{ 0, 0, 76},{ 0, 0, 80},{ 0, 0, 88},
{ 0, 0, 96},{ 0, 0,100},{ 0, 0,108},{ 0, 0,116},{ 0, 0,120},{ 0, 0,128},{ 0, 0,132},{ 0, 0,140},
{ 0, 0,148},{ 0, 0,152},{ 0, 0,160},{ 0, 0,164},{ 0, 0,172},{ 0, 0,180},{ 0, 0,184},{ 0, 0,192},
{ 0, 0,200},{ 0, 4,200},{ 0, 12,200},{ 0, 16,204},{ 0, 24,204},{ 0, 28,208},{ 0, 36,208},{ 0, 40,208},
{ 0, 48,212},{ 0, 56,212},{ 0, 60,216},{ 0, 68,216},{ 0, 72,216},{ 0, 80,220},{ 0, 84,220},{ 0, 92,224},
{ 0,100,224},{ 0,104,224},{ 0,112,228},{ 0,116,228},{ 0,124,232},{ 0,128,232},{ 0,136,232},{ 0,140,236},
{ 0,148,236},{ 0,156,240},{ 0,160,240},{ 0,168,240},{ 0,172,244},{ 0,180,244},{ 0,184,248},{ 0,192,248},
{ 0,200,252},{ 4,200,252},{ 12,200,252},{ 20,204,252},{ 28,204,252},{ 36,208,252},{ 44,208,252},{ 52,208,252},
{ 60,212,252},{ 68,212,252},{ 76,216,252},{ 84,216,252},{ 92,216,252},{100,220,252},{108,220,252},{116,224,252},
{124,224,252},{132,224,252},{140,228,252},{148,228,252},{156,232,252},{164,232,252},{172,232,252},{180,236,252},
{188,236,252},{196,240,252},{204,240,252},{212,240,252},{220,244,252},{228,244,252},{236,248,252},{244,248,252},
{252,252,252},{248,252,252},{244,252,252},{240,252,252},{232,252,252},{228,252,252},{224,252,252},{216,252,252},
{212,252,252},{208,252,252},{200,252,252},{196,252,252},{192,252,252},{184,252,252},{180,252,252},{176,252,252},
{168,252,252},{164,252,252},{160,252,252},{156,252,252},{148,252,252},{144,252,252},{140,252,252},{132,252,252},
{128,252,252},{124,252,252},{116,252,252},{112,252,252},{108,252,252},{100,252,252},{ 96,252,252},{ 92,252,252},
{ 84,252,252},{ 80,252,252},{ 76,252,252},{ 72,252,252},{ 64,252,252},{ 60,252,252},{ 56,252,252},{ 48,252,252},
{ 44,252,252},{ 40,252,252},{ 32,252,252},{ 28,252,252},{ 24,252,252},{ 16,252,252},{ 12,252,252},{ 8,252,252},
{ 0,252,252},{ 0,248,252},{ 0,244,252},{ 0,240,252},{ 0,232,252},{ 0,228,252},{ 0,224,252},{ 0,216,252},
{ 0,212,252},{ 0,208,252},{ 0,200,252},{ 0,196,252},{ 0,192,252},{ 0,184,252},{ 0,180,252},{ 0,176,252},
{ 0,168,252},{ 0,164,252},{ 0,160,252},{ 0,156,252},{ 0,148,252},{ 0,144,252},{ 0,140,252},{ 0,132,252},
{ 0,128,252},{ 0,124,252},{ 0,116,252},{ 0,112,252},{ 0,108,252},{ 0,100,252},{ 0, 96,252},{ 0, 92,252},
{ 0, 84,252},{ 0, 80,252},{ 0, 76,252},{ 0, 72,252},{ 0, 64,252},{ 0, 60,252},{ 0, 56,252},{ 0, 48,252},
{ 0, 44,252},{ 0, 40,252},{ 0, 32,252},{ 0, 28,252},{ 0, 24,252},{ 0, 16,252},{ 0, 12,252},{ 0, 8,252},
{ 0, 0,252},{ 0, 0,248},{ 0, 0,244},{ 0, 0,240},{ 0, 0,236},{ 0, 0,232},{ 0, 0,228},{ 0, 0,224},
{ 0, 0,220},{ 0, 0,216},{ 0, 0,212},{ 0, 0,208},{ 0, 0,204},{ 0, 0,200},{ 0, 0,196},{ 0, 0,192},
{ 0, 0,188},{ 0, 0,184},{ 0, 0,180},{ 0, 0,176},{ 0, 0,172},{ 0, 0,168},{ 0, 0,164},{ 0, 0,160},
{ 0, 0,156},{ 0, 0,152},{ 0, 0,148},{ 0, 0,144},{ 0, 0,140},{ 0, 0,136},{ 0, 0,132},{ 0, 0,128},
{ 0, 0,124},{ 0, 0,120},{ 0, 0,116},{ 0, 0,112},{ 0, 0,108},{ 0, 0,104},{ 0, 0,100},{ 0, 0, 96},
{ 0, 0, 92},{ 0, 0, 88},{ 0, 0, 84},{ 0, 0, 80},{ 0, 0, 76},{ 0, 0, 72},{ 0, 0, 68},{ 0, 0, 64},
{ 0, 0, 60},{ 0, 0, 56},{ 0, 0, 52},{ 0, 0, 48},{ 0, 0, 44},{ 0, 0, 40},{ 0, 0, 36},{ 0, 0, 32},
{ 0, 0, 28},{ 0, 0, 24},{ 0, 0, 20},{ 0, 0, 16},{ 0, 0, 12},{ 0, 0, 8},{ 0, 0, 0},{ 0, 0, 0}
};