diff options
Diffstat (limited to 'src/cmd/plot/libplot/parabola.c')
-rw-r--r-- | src/cmd/plot/libplot/parabola.c | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/src/cmd/plot/libplot/parabola.c b/src/cmd/plot/libplot/parabola.c new file mode 100644 index 00000000..212b9c97 --- /dev/null +++ b/src/cmd/plot/libplot/parabola.c @@ -0,0 +1,32 @@ +#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); +} |