Data commit

Task/Draw-a-sphere/C/draw-a-sphere-1.c

@@ -0,0 +1,57 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <math.h>
+
+const char *shades = ".:!*oe&#%@";
+
+double light[3] = { 30, 30, -50 };
+void normalize(double * v)
+{
+        double len = sqrt(v[0]*v[0] + v[1]*v[1] + v[2]*v[2]);
+        v[0] /= len; v[1] /= len; v[2] /= len;
+}
+
+double dot(double *x, double *y)
+{
+        double d = x[0]*y[0] + x[1]*y[1] + x[2]*y[2];
+        return d < 0 ? -d : 0;
+}
+
+void draw_sphere(double R, double k, double ambient)
+{
+        int i, j, intensity;
+        double b;
+        double vec[3], x, y;
+        for (i = floor(-R); i <= ceil(R); i++) {
+                x = i + .5;
+                for (j = floor(-2 * R); j <= ceil(2 * R); j++) {
+                        y = j / 2. + .5;
+                        if (x * x + y * y <= R * R) {
+                                vec[0] = x;
+                                vec[1] = y;
+                                vec[2] = sqrt(R * R - x * x - y * y);
+                                normalize(vec);
+                                b = pow(dot(light, vec), k) + ambient;
+                                intensity = (1 - b) * (sizeof(shades) - 1);
+                                if (intensity < 0) intensity = 0;
+                                if (intensity >= sizeof(shades) - 1)
+                                        intensity = sizeof(shades) - 2;
+                                putchar(shades[intensity]);
+                        } else
+                                putchar(' ');
+                }
+                putchar('\n');
+        }
+}
+
+
+int main()
+{
+        normalize(light);
+        draw_sphere(20, 4, .1);
+        draw_sphere(10, 2, .4);
+
+        return 0;
+}

Task/Draw-a-sphere/C/draw-a-sphere-2.c

@@ -0,0 +1,162 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+
+#define MAXD 8
+int g[] = { -1, 1, -1, 1 };
+/* Perlin-like noise */
+static 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;
+}