Farbfeld test

abstract.c

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

#include <arpa/inet.h>

#define S_WIDTH 80
#define S_HEIGHT 80
#define S_IDX(X, Y) ((X) + (S_WIDTH) * (Y))

#define ftoff(X) htons((X) >= 1.0 ? 0xFFFF : (X) * 0x10000)

struct colour {
	float r, g, b;
};

int
main(void)
{
	uint32_t ff_width = htonl(S_WIDTH);
	uint32_t ff_height = htonl(S_HEIGHT);
	struct {
		uint16_t r, g, b, a;
	} ff_pixel = {.a = 0xFFFF};

	struct colour *image = calloc(S_WIDTH * S_HEIGHT, sizeof(*image));

	/* Draw something abstract */
	for (int i = 0; i < S_WIDTH; i++) {
		for (int j = 0; j < 10; j++) {
			image[S_IDX(10 + j, i)].r = 0.7;
			image[S_IDX(i, 10 + j)].g = 0.7;
			image[S_IDX(i, 60 + j)].b = 0.7;
			image[S_IDX(60 + j, i)].r = 1.0;
			image[S_IDX(60 + j, i)].g = 1.0;
			image[S_IDX(60 + j, i)].b = 1.0;
		}
	}

	/* Write image as farbfeld */
	fwrite("farbfeld", 8, 1, stdout);
	fwrite(&ff_width, sizeof(ff_width), 1, stdout);
	fwrite(&ff_height, sizeof(ff_width), 1, stdout);

	for (int i = 0; i < S_WIDTH * S_HEIGHT; ++i) {
		ff_pixel.r = ftoff(image[i].r);
		ff_pixel.g = ftoff(image[i].g);
		ff_pixel.b = ftoff(image[i].b);
		fwrite(&ff_pixel, sizeof(ff_pixel), 1, stdout);
	}

	return 0;
}

abstract.ff

abstract.png

Makefile

CC = gcc
CFLAGS = -fopenmp -lm -std=c99 -pedantic -Wall

TARGETS = abstract.ff

.PHONY: default
default: $(TARGETS) $(TARGETS:.ff=.png)

%.png: %.ff
	ff2png < $< > $@

%.ff: %.c
	$(CC) $(CFLAGS) -o $(@:.ff=) $^
	./$(@:.ff=) > $@

%: %.c

.PHONY: clean
clean:
	rm -f *.png *.ff $(TARGETS) $(TARGETS:.ff=.png) $(TARGETS:.ff=)

mandlebrot.c

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

#include <arpa/inet.h>

#include <omp.h>
#include <complex.h>

#define REALMIN -0.80
#define REALMAX -0.70
#define IMAGMIN  0.1
#define IMAGMAX  0.2

#define REALMID -0.75
#define IMAGMID 0.15
#define S_SCALE 6000

#define S_WIDTH 600
#define S_HEIGHT 600
#define S_IDX(X, Y) ((X) + S_WIDTH * (Y))

#define MAXITER 1000

#define ftoff(X) htons((X) >= 1.0 ? 0xFFFF : (X) * 0x10000)

#define ftoffspecr(X) ftoff(1.0 - (X))
#define ftoffspecg(X) ftoff((X) * (1.0 - (X)))
#define ftoffspecb(X) ftoff(X)

struct rgba {
	uint16_t r, g, b, a;
};

int
escape_time(double complex c)
{
	double complex z = c;
	int t = 0;
	for (; cabs(z) < 2 && t < MAXITER; ++t) {
		z = z * z + c;
	}
	if (t == MAXITER)
		t = -1;
	return t;
}

/*
void
log_mb(double complex c)
{
	int cv;
	if ((cv = escape_time(c)) > 0)
		fprintf(stderr, "%f + %fi escapes in %d iterations\n",
		        creal(c), cimag(c), cv);
	else
		fprintf(stderr, "%f + %fi is in the mandlebrot set\n",
		        creal(c), cimag(c));
}
*/

int
main(void)
{
	uint32_t ff_width = htonl(S_WIDTH);
	uint32_t ff_height = htonl(S_HEIGHT);

	struct rgba *ff_image = calloc(S_WIDTH * S_HEIGHT, sizeof(*ff_image));
	for (int i = 0; i < S_WIDTH * S_HEIGHT; ++i)
		ff_image[i].a = 0xFFFF;

	/* Projection values */
	double xscale = ((double) REALMAX - REALMIN) / S_WIDTH;
	double yscale = ((double) IMAGMAX - IMAGMIN) / S_HEIGHT;
	double xshift = REALMIN + xscale / 2;
	double yshift = IMAGMIN + yscale / 2;

	#pragma omp parallel for
	for (int j = 0; j < S_HEIGHT; j++) {
		struct rgba *pixel;
		double complex c;
		int cv;
		for (int i = 0; i < S_WIDTH; i++) {
			c = (xscale * i + xshift) + I * (yscale * j + yshift);
			if ((cv = escape_time(c)) > 0) {
				pixel = &ff_image[S_IDX(i, S_HEIGHT - j)];
				pixel->r = ftoffspecr((double) MAXITER / cv);
				pixel->g = ftoffspecg((double) MAXITER / cv);
				pixel->b = ftoffspecb((double) MAXITER / cv);
			}
		}
	}

	/* Write image as farbfeld */
	fwrite("farbfeld", 8, 1, stdout);
	fwrite(&ff_width, sizeof(ff_width), 1, stdout);
	fwrite(&ff_height, sizeof(ff_width), 1, stdout);
	fwrite(ff_image, sizeof(struct rgba), S_WIDTH * S_HEIGHT, stdout);

	return 0;
}