Data commit

Task/Sierpinski-triangle-Graphical/C/sierpinski-triangle-graphical.c

@@ -0,0 +1,113 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+
+long long x, y, dx, dy, scale, clen, cscale;
+typedef struct { double r, g, b; } rgb;
+rgb ** pix;
+
+void sc_up()
+{
+	scale *= 2; x *= 2; y *= 2;
+	cscale *= 3;
+}
+
+void h_rgb(long long x, long long y)
+{
+	rgb *p = &pix[y][x];
+
+#	define SAT 1
+	double h = 6.0 * clen / cscale;
+	double VAL = 1;
+	double c = SAT * VAL;
+	double X = c * (1 - fabs(fmod(h, 2) - 1));
+
+	switch((int)h) {
+	case 0: p->r += c; p->g += X; return;
+	case 1:	p->r += X; p->g += c; return;
+	case 2: p->g += c; p->b += X; return;
+	case 3: p->g += X; p->b += c; return;
+	case 4: p->r += X; p->b += c; return;
+	default:
+		p->r += c; p->b += X;
+	}
+}
+
+void iter_string(const char * str, int d)
+{
+	long long len;
+	while (*str != '\0') {
+		switch(*(str++)) {
+		case 'X':
+			if (d)	iter_string("XHXVX", d - 1);
+			else{
+				clen ++;
+				h_rgb(x/scale, y/scale);
+				x += dx;
+				y -= dy;
+			}
+			continue;
+		case 'V':
+			len = 1LLU << d;
+			while (len--) {
+				clen ++;
+				h_rgb(x/scale, y/scale);
+				y += dy;
+			}
+			continue;
+		case 'H':
+			len = 1LLU << d;
+			while(len --) {
+				clen ++;
+				h_rgb(x/scale, y/scale);
+				x -= dx;
+			}
+			continue;
+		}
+	}
+}
+
+void sierp(long leng, int depth)
+{
+	long i;
+	long h = leng + 20, w = leng + 20;
+
+	/* allocate pixel buffer */
+	rgb *buf = malloc(sizeof(rgb) * w * h);
+	pix = malloc(sizeof(rgb *) * h);
+	for (i = 0; i < h; i++)
+		pix[i] = buf + w * i;
+	memset(buf, 0, sizeof(rgb) * w * h);
+
+        /* init coords; scale up to desired; exec string */
+	x = y = 10; dx = leng; dy = leng; scale = 1; clen = 0; cscale = 3;
+	for (i = 0; i < depth; i++) sc_up();
+	iter_string("VXH", depth);
+
+	/* write color PNM file */
+	unsigned char *fpix = malloc(w * h * 3);
+	double maxv = 0, *dbuf = (double*)buf;
+
+	for (i = 3 * w * h - 1; i >= 0; i--)
+		if (dbuf[i] > maxv) maxv = dbuf[i];
+	for (i = 3 * h * w - 1; i >= 0; i--)
+		fpix[i] = 255 * dbuf[i] / maxv;
+
+	printf("P6\n%ld %ld\n255\n", w, h);
+	fflush(stdout); /* printf and fwrite may treat buffer differently */
+	fwrite(fpix, h * w * 3, 1, stdout);
+}
+
+int main(int c, char ** v)
+{
+	int size, depth;
+
+	depth  = (c > 1) ? atoi(v[1]) : 10;
+	size = 1 << depth;
+
+	fprintf(stderr, "size: %d depth: %d\n", size, depth);
+	sierp(size, depth + 2);
+
+	return 0;
+}