task7 initial commit

1 files changed, 139 insertions, 0 deletions

diff --git a/7_2/src/figure.c b/7_2/src/figure.c
new file mode 100644
index 0000000..290d4af
--- /dev/null
+++ b/7_2/src/figure.c
@@ -0,0 +1,139 @@
+
+#include "figure.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+
+void (*const draw_lookup[])(const struct figure *, struct drawable *) = {
+	[F_NONE] = NULL,
+	[F_POINT] = draw_point,
+	[F_RECT] = draw_rect,
+	[F_LINE] = draw_line,
+	[F_CIRCLE] = draw_circle
+};
+
+void swapl(long *x, long *y) {
+	long tmp = *x;
+	*x = *y;
+	*y = tmp;
+}
+
+struct figure figure_point(vector2 p) {
+	return (struct figure) {
+		.type = F_POINT,
+		.point.coords = p,
+		.draw = draw_point
+	};
+}
+
+struct figure figure_rect(vector2 upleft, vector2 downright) {
+	return (struct figure) {
+		.type = F_RECT,
+		.rect = {upleft, downright},
+		.draw = draw_rect
+	};
+}
+
+struct figure figure_line(vector2 start, vector2 end) {
+	return (struct figure) {
+		.type = F_LINE,
+		.line = {start, end},
+		.draw = draw_line
+	};
+}
+
+struct figure figure_circle(vector2 center, long radius) {
+	return (struct figure) {
+		.type = F_CIRCLE,
+		.circle = {center, radius},
+		.draw = draw_circle
+	};
+}
+
+
+void draw_point(const struct figure *self, struct drawable *d) {
+	d->put(d, self->point.coords.x, self->point.coords.y);
+}
+
+void draw_rect(const struct figure *self, struct drawable *d) {
+	vector2 upleft = self->rect.upleft;
+	vector2 downright = self->rect.downright;
+	for (long i = upleft.x; i < downright.x + 1; ++i) {
+		d->put(d, i, upleft.y);
+		d->put(d, i, downright.y);
+	} 
+	for (long j = upleft.y + 1; j < downright.y; ++j) {
+		d->put(d, upleft.x, j);
+		d->put(d, downright.x, j);
+	}
+}
+
+void draw_line(const struct figure *self, struct drawable *d) {
+	vector2 start = self->line.start;
+	vector2 end = self->line.end;
+	char gt45 = labs(end.y - start.y) > labs(end.x - start.x);
+	long x0 = start.x, y0 = start.y, 
+	       x1 = end.x, y1 = end.y;
+	if (gt45) {
+		swapl(&x0, &y0);
+		swapl(&x1, &y1);
+	}
+	if (x0 > x1) {
+		swapl(&x0, &x1);
+		swapl(&y0, &y1);
+	}
+	long dy = labs(y1-y0),
+	     dx = x1 - x0,
+	     err = dx >> 1, // *2
+	     yinc = (y1 > y0 ? 1 : -1);
+
+	for (long x = x0, y = y0; x <= x1; ++x) {
+		if (gt45) d->put(d, y, x);
+		else d->put(d, x, y);
+		err -= dy;
+		if (err < 0) {
+			y += yinc;
+			err += dx;
+		}
+	}
+}
+
+void draw_circle(const struct figure *self, struct drawable *f) {
+	const vector2 p = self->circle.center;
+	const long rad = self->circle.rad - 1;
+	const long pi4 = ceil(M_SQRT1_2 * rad);
+	long x0 = 0, y0 = rad;
+	do {
+		// выглядит коряво, зато в 8 раз меньше повторений цикла
+		f->put(f, p.x-x0, p.y-y0); // 3 четверть
+		f->put(f, p.x-x0, p.y+y0); // 2 чет.
+		f->put(f, p.x+x0, p.y-y0); // 4 ч.
+		f->put(f, p.x+x0, p.y+y0); // 1 ч
+		f->put(f, p.x-y0, p.y-x0); 
+		f->put(f, p.x-y0, p.y+x0);
+		f->put(f, p.x+y0, p.y-x0);
+		f->put(f, p.x+y0, p.y+x0);
+		++x0;
+		// вычисляем x^2 + (y+1/2)^2 - r^2
+		// раскрыли скобки и умножили на 4, чтобы не иметь дело 
+		// с дробными числами (они медленные)
+		long func = 4*x0*x0 + 4*y0*y0 - 4*y0 + 1 - 4*rad*rad;
+		y0 = (func >= 0 ? y0 - 1 : y0);
+	} while (x0 < pi4);
+}
+
+void print_figure(const struct figure *self) {
+	printf("figure {\n\t.type = %i\n\t{%li, %li},\n\t", self->type, self->line.start.x, self->line.start.y);
+	switch (self->type) {
+	case F_LINE:
+	case F_RECT:
+		printf("{%li, %li}\n\t", self->line.end.x, self->line.end.y);
+		break;
+	case F_CIRCLE:
+		printf("%li\n\t", self->circle.rad);
+		// fallthrough
+	case F_NONE:
+	case F_POINT:;		
+	}
+	printf(".draw = %p\n}\n", self->draw);
+}