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package geo
import (
"math"
"testing"
"github.com/paulmach/orb"
)
func TestArea(t *testing.T) {
for _, g := range orb.AllGeometries {
// should not panic with unsupported type
Area(g)
}
}
func TestSignedArea(t *testing.T) {
area := 12392.029
cases := []struct {
name string
ring orb.Ring
result float64
}{
{
name: "simple box, ccw",
ring: orb.Ring{{0, 0}, {0.001, 0}, {0.001, 0.001}, {0, 0.001}, {0, 0}},
result: area,
},
{
name: "simple box, cc",
ring: orb.Ring{{0, 0}, {0, 0.001}, {0.001, 0.001}, {0.001, 0}, {0, 0}},
result: -area,
},
{
name: "even number of points",
ring: orb.Ring{{0, 0}, {0.001, 0}, {0.001, 0.001}, {0.0004, 0.001}, {0, 0.001}, {0, 0}},
result: area,
},
{
name: "3 points",
ring: orb.Ring{{0, 0}, {0.001, 0}, {0.001, 0.001}},
result: area / 2.0,
},
{
name: "4 points",
ring: orb.Ring{{0, 0}, {0.001, 0}, {0.001, 0.001}, {0, 0}},
result: area / 2.0,
},
{
name: "6 points",
ring: orb.Ring{{0.001, 0.001}, {0.002, 0.001}, {0.002, 0.0015}, {0.002, 0.002}, {0.001, 0.002}, {0.001, 0.001}},
result: area,
},
}
for _, tc := range cases {
t.Run(tc.name, func(t *testing.T) {
val := SignedArea(tc.ring)
if math.Abs(val-tc.result) > 1 {
t.Errorf("wrong area: %v != %v", val, tc.result)
}
// should work without redudant last point.
if tc.ring[0] == tc.ring[len(tc.ring)-1] {
tc.ring = tc.ring[:len(tc.ring)-1]
val = SignedArea(tc.ring)
if math.Abs(val-tc.result) > 1 {
t.Errorf("wrong area: %v != %v", val, tc.result)
}
}
})
}
}
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