September 2017 Update

Task/Draw-a-sphere/C/draw-a-sphere-3.c

@@ -1,162 +0,0 @@
-#include <stdio.h>
-#include <stdlib.h>
-#include <math.h>
-
-#define MAXD 8
-int g[] = { -1, 1, -1, 1 };
-/* Perlin-like noise */
-inline void
-hashed(int *data, int *out, int len) {
-#	define ror(a, d) ((a << (d)) | (a >> (32 - d)))
-	register unsigned int h = 0x12345678, tmp;
-	unsigned int *d = (void*)data;
-	int i = len;
-
-	while (i--) {
-		tmp = *d++;
-		h += ror(h, 15) ^ ror(tmp, 5);
-	}
-
-	h ^= ror(h, 7);
-	h += ror(h, 23);
-	h ^= ror(h, 19);
-	h += ror(h, 11);
-	h ^= ror(h, 13);
-	h += ror(h, 17);
-#	undef ror
-	for (i = len; i--; ) {
-		out[i] = g[h & 3];
-		h >>= 2;
-	}
-}
-
-double scale[MAXD], scale_u[MAXD];
-void noise_init()
-{
-	int i;
-	for (i = 1; i < MAXD; i++) {
-		scale[i] = 1 / (1 + sqrt(i + 1));
-		scale_u[i] = scale[i] / sqrt(i + 1);
-	}
-}
-
-double noise(double *x, int d)
-{
-#	define sum(s, x) for (s = 0, j = 0; j < d; j++) s += x
-	register int i, j;
-	int n[MAXD], o[MAXD], g[MAXD], tmp;
-	double s, r, t, w, ret, u[MAXD];
-
-	sum(s, x[j]);
-	s *= scale[d];
-
-	for (i = 0; i < d; i++) {
-		o[i] = i;
-		t = x[i] + s;
-		u[i] = t - (n[i] = floor(t));
-	}
-	o[d] = 0;
-
-	for (i = 0; i < d - 1; i++)
-		for (j = i; j < d; j++)
-			if (u[o[i]] < u[o[j]])
-				tmp = o[i], o[i] = o[j], o[j] = tmp;
-
-	ret = w = 0, r = 1;
-	for (s = 0, j = 0; j < d; j++) s += n[j];
-	s *= scale_u[d];
-
-	for (i = 0; i <= d; i++) {
-		for (j = 0; j < d; j++)
-			u[j] = x[j] + s - n[j];
-
-		for (t = (d + 1.) / (2 * d), j = 0; j < d; j++) {
-			t -= u[j] * u[j];
-			if (t <= 0) break;
-		}
-
-		if (t >= 0) {
-			r = 0;
-			hashed(n, g, d);
-			for (j = 0; j < d; j++)
-				if (g[j]) r += (g[j] == 1 ? u[j] : -u[j]);
-			t *= t;
-			ret += r * t * t;
-		}
-
-		if (i < d) {
-			n[o[i]]++;
-			s += scale_u[d];
-		}
-	}
-	return ret * (d * d);
-}
-
-double get_noise2(double x, double y)
-{
-	int i, ws;
-	double r = 0, v[2];
-
-	for (i = 1, ws = 0; i <= 128; i <<= 1) {
-		v[0] = x * i, v[1] = y * i;
-		r += noise(v, 2);
-		ws ++;
-	}
-	r /= ws;
-	return r;
-}
-
-double get_noise3(double x, double y, double z)
-{
-	int i, ws;
-	double r = 0, v[3], w;
-
-	for (i = 1, ws = 0; i <= 32; i <<= 1) {
-		v[0] = x * i, v[1] = y * i, v[2] = z * i;
-		w = 1./sqrt(i);
-		r += noise(v, 3) * w;
-		ws += w;
-	}
-	return r / ws;
-}
-
-
-int main(int c, char** v)
-{
-	unsigned char pix[256 * 256], *p;
-	int i, j;
-	double x, y, z, w;
-	FILE *fp;
-
-	noise_init();
-
-	for (p = pix, i = 0; i < 256 * 256; i++) *p++ = 0;
-
-	for (p = pix, i = 0; i < 256; i++) {
-		y = (i - 128) / 125.;
-		for (j = 0; j < 256; j++, p++) {
-			x = (j - 128) / 125.;
-			*p = (get_noise2(i/256., j/256.) + 1) / 6 * i;
-
-			z = 1- x*x - y*y;
-			if (z < 0) continue;
-
-			z = sqrt(z);
-
-			w = get_noise3(x, y, z);
-
-			w = (w + 1) / 2;
-			w *= (1 + x - y + z) / 3.5;
-			if (w < 0) w = 0;
-
-			*p = w * 255;
-		}
-	}
-
-	fp = fopen("out.pgm", "w+");
-	fprintf(fp, "P5\n256 256\n255\n");
-	fwrite(pix, 1, 256 * 256, fp);
-	fclose(fp);
-
-	return 0;
-}