go-curve/circle_test.go at master · dominikh/go-curve

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package curve

import (

"math"

"slices"

"testing"

)

func TestCircleAreaSign(t *testing.T) {

approxEqual := func(x, y float64) bool {

return math.Abs(x-y) < 1e-7

}

center := Pt(5, 5)

c := Circle{center, 5}

if a := c.Area(); !approxEqual(a, 25*math.Pi) {

t.Errorf("got area %v, expected %v", a, 25.0*math.Pi)

}

if w := c.Winding(center); w != 1 {

t.Errorf("got winding number %d, expected 1", w)

}

p := BezPath(slices.Collect(c.PathElements(1e-9)))

if ca, pa := c.Area(), p.SignedArea(); !approxEqual(ca, pa) {

t.Errorf("got areas %v and %v, expected them to be equal", ca, pa)

}

if cw, pw := c.Winding(center), p.Winding(center); cw != pw {

t.Errorf("got winding numbers %d and %d, expected them to be equal", cw, pw)

}

cNegRadius := Circle{center, -5}

if a := cNegRadius.Area(); !approxEqual(a, 25.0*math.Pi) {

t.Errorf("got area %v, expected %v", a, 25.0*math.Pi)

}

if w := cNegRadius.Winding(center); w != 1 {

t.Errorf("got winding number %d, expected 1", w)

}

pNegRadius := BezPath(slices.Collect(cNegRadius.PathElements(1e-9)))

if ca, pa := cNegRadius.Area(), pNegRadius.SignedArea(); !approxEqual(ca, pa) {

t.Errorf("got areas %v and %v, expected them to be equal", ca, pa)

}

if cw, pw := cNegRadius.Winding(center), pNegRadius.Winding(center); cw != pw {

t.Errorf("got winding numbers %d and %d, expected them to be equal", cw, pw)

}