#include "mplot.h" | |
void parabola(double x0, double y0, double x1, double y1, double xb, double yb){ | |
register double x, y, t; | |
double c0x, c0y, c1x, c1y; | |
double dt, d2, d1; | |
d1 = sqrt((xb - x0) * (xb - x0) + (yb - y0) * (yb - y0)); | |
d2 = sqrt((xb - x1) * (xb - x1) + (yb - y1) * (yb - y1)); | |
if (d1 <= e1->quantum || d2 <= e1->quantum) { | |
plotline(x0, y0, x1, y1); | |
return; | |
} | |
c0x = x0 + x1 - 2. * xb; | |
c1x = 2. * (xb - x0); | |
c0y = y0 + y1 - 2. * yb; | |
c1y = 2. * (yb - y0); | |
move(x0, y0); | |
dt = e1->quantum / d1; | |
dt /= e1->grade; | |
for (t = dt; t < 0.5; t += dt) { | |
x = (c0x * t + c1x) * t + x0; | |
y = (c0y * t + c1y) * t + y0; | |
vec(x, y); | |
} | |
dt = e1->quantum / d2; | |
dt /= e1->grade; | |
for (; t < 1.0; t += dt) { | |
x = (c0x * t + c1x) * t + x0; | |
y = (c0y * t + c1y) * t + y0; | |
vec(x, y); | |
} | |
vec(x1, y1); | |
} |