1 4314729d 2004-04-14 devnull #include "mplot.h"
 2 4314729d 2004-04-14 devnull void parabola(double x0, double y0, double x1, double y1, double xb, double yb){
 3 4314729d 2004-04-14 devnull 	register double x, y, t;
 4 4314729d 2004-04-14 devnull 	double	c0x, c0y, c1x, c1y;
 5 4314729d 2004-04-14 devnull 	double	dt, d2, d1;
 6 4314729d 2004-04-14 devnull 	d1 = sqrt((xb - x0) * (xb - x0) + (yb - y0) * (yb - y0));
 7 4314729d 2004-04-14 devnull 	d2 = sqrt((xb - x1) * (xb - x1) + (yb - y1) * (yb - y1));
 8 4314729d 2004-04-14 devnull 	if (d1 <= e1->quantum || d2 <= e1->quantum) { 
 9 4314729d 2004-04-14 devnull 		plotline(x0, y0, x1, y1); 
10 4314729d 2004-04-14 devnull 		return; 
11 4314729d 2004-04-14 devnull 	}
12 4314729d 2004-04-14 devnull 	c0x = x0 + x1 - 2. * xb; 
13 4314729d 2004-04-14 devnull 	c1x = 2. * (xb - x0);
14 4314729d 2004-04-14 devnull 	c0y = y0 + y1 - 2. * yb; 
15 4314729d 2004-04-14 devnull 	c1y = 2. * (yb - y0);
16 4314729d 2004-04-14 devnull 	move(x0, y0);
17 4314729d 2004-04-14 devnull 	dt = e1->quantum / d1;
18 4314729d 2004-04-14 devnull 	dt /= e1->grade;
19 4314729d 2004-04-14 devnull 	for (t = dt; t < 0.5; t += dt) {
20 4314729d 2004-04-14 devnull 		x = (c0x * t + c1x) * t + x0;
21 4314729d 2004-04-14 devnull 		y = (c0y * t + c1y) * t + y0;
22 4314729d 2004-04-14 devnull 		vec(x, y);
23 4314729d 2004-04-14 devnull 	}
24 4314729d 2004-04-14 devnull 	dt = e1->quantum / d2;
25 4314729d 2004-04-14 devnull 	dt /= e1->grade;
26 4314729d 2004-04-14 devnull 	for (; t < 1.0; t += dt) {
27 4314729d 2004-04-14 devnull 		x = (c0x * t + c1x) * t + x0;
28 4314729d 2004-04-14 devnull 		y = (c0y * t + c1y) * t + y0;
29 4314729d 2004-04-14 devnull 		vec(x, y);
30 4314729d 2004-04-14 devnull 	}
31 4314729d 2004-04-14 devnull 	vec(x1, y1);
32 4314729d 2004-04-14 devnull }