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Merge in changes from oceanful #3

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merged 4 commits into from
Sep 4, 2021
Merged

Merge in changes from oceanful #3

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1e0794f
Polygon.MakeValid() removes self-intersections and degenerate edges (…
oceanful Oct 9, 2020
7000f73
Fix calculation of "inout" fields for overlapping segments (#12)
oceanful Oct 16, 2020
202b915
Add tests for many edges that share a vertex. (#14)
oceanful Oct 19, 2020
4f79745
Merge changes
ctessum Sep 4, 2021
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2 changes: 1 addition & 1 deletion README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@ The original paper describes the algorithm as performing in time _O((n+k) log n)
## Limitations

- Although the algorithm will not produce self-intersecting polygons, it is not designed
to handle them either. To remove self-intersections from polygons, use `Simplify()`.
to handle them either. To remove self-intersections from polygons, use `MakeValid()`.

## Example

Expand Down
303 changes: 299 additions & 4 deletions bugs_test.go
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Expand Up @@ -90,12 +90,23 @@ func (cases testCases) verify(t *testing.T) {
}
expected[i] = path
}
normalizedExpected := dump(expected)

result := dump(c.subject.Construct(c.op, c.clipping))
if result != dump(expected) {
t.Errorf("case %d: %v\nsubject: %v\nclipping: %v\nexpected: %v\ngot: %v",
if result != normalizedExpected {
t.Errorf("case %d: %v\nsubject: %v\nclipping: %v\nexpected: %v\ngot result: %v",
i, c.op, c.subject, c.clipping, c.result, result)
}
validatedResult := dump(c.subject.MakeValid().Construct(c.op, c.clipping.MakeValid()))
if validatedResult != normalizedExpected {
t.Errorf("case %d: %v\nsubject: %v\nclipping: %v\nexpected: %v\ngot validated result: %v",
i, c.op, c.subject, c.clipping, c.result, validatedResult)
}
validatedExpected := dump(expected.MakeValid())
if validatedExpected != normalizedExpected {
t.Errorf("case %d: %v\nsubject: %v\nclipping: %v\nexpected: %v\ngot validated expected: %v",
i, c.op, c.subject, c.clipping, c.result, validatedExpected)
}
})
}
}
Expand Down Expand Up @@ -323,14 +334,14 @@ func TestIntersectionFalsePositives(t *testing.T) {
clipping: polyclip.Polygon{{
{100.00000001, 100},
{100, 99.99999988569955},
{99.99999999, 100.00000000000001},
{99.99999998, 100.00000000000001},
{100, 100.00000011430046},
{100.00000001, 100},
}},
result: polyclip.Polygon{{
{100.00000001, 100},
{100, 99.99999988569955},
{99.99999999, 100.00000000000001},
{99.99999998, 100.00000000000001},
{100, 100.00000011430046},
{100.00000001, 100},
}},
Expand Down Expand Up @@ -564,6 +575,191 @@ func TestSelfIntersectionAvoidance(t *testing.T) {
}.verify(t)
}

func TestOverlappingSegments(t *testing.T) {
testCases{
{
// ----------
// | /
// | /
// | /
// | /
// | /|
// | /_|
// | /
// | /
// |/
op: polyclip.UNION,
subject: polyclip.Polygon{{
{0, 0},
{10, 0},
{0, 10},
}},
clipping: polyclip.Polygon{{
{6, 5},
{6, 4},
{5, 5},
}},
result: polyclip.Polygon{{
{0, 0},
{10, 0},
{6, 4},
{6, 5},
{5, 5},
{0, 10},
}},
},
{
// ----------
// | /
// | /
// | /
// | __/
// | | /
// | |/
// | /
// | /
// |/
op: polyclip.UNION,
subject: polyclip.Polygon{{
{0, 0},
{10, 0},
{0, 10},
}},
clipping: polyclip.Polygon{{
{6, 4},
{4, 5},
{5, 5},
}},
result: polyclip.Polygon{{
{0, 0},
{10, 0},
{6, 4},
{5, 5},
{0, 10},
}},
},
{
// |\
// | \
// | \__
// | \ |
// | \|
// | \
// | \
// | \
// ----------
op: polyclip.UNION,
subject: polyclip.Polygon{{
{0, 10},
{10, 10},
{0, 0},
}},
clipping: polyclip.Polygon{{
{6, 5},
{6, 6},
{5, 5},
}},
result: polyclip.Polygon{{
{0, 0},
{5, 5},
{6, 5},
{6, 6},
{10, 10},
{0, 10},
}},
},
{
// |\
// | \
// | \
// | |\
// | |_\
// | \
// | \
// | \
// ----------
op: polyclip.UNION,
subject: polyclip.Polygon{{
{0, 10},
{10, 10},
{0, 0},
}},
clipping: polyclip.Polygon{{
{5, 5},
{5, 6},
{6, 6},
}},
result: polyclip.Polygon{{
{0, 0},
{5, 5},
{6, 6},
{10, 10},
{0, 10},
}},
},
{
op: polyclip.UNION,
subject: polyclip.Polygon{{
{40131, 8372}, {40127, 8374}, {40126, 8375}, {40125, 8375}, {40122, 8377}, {40143, 8369},
}},
clipping: polyclip.Polygon{{
{40106, 8376}, {40128, 8373}, {40126, 8375},
}},
result: polyclip.Polygon{{
{40106, 8376}, {40128, 8373}, {40127, 8374}, {40131, 8372}, {40143, 8369}, {40122, 8377}, {40124.91891891892, 8375.054054054053},
}},
},
}.verify(t)
}

func TestSharedVertex(t *testing.T) {
// Three triangles that share a single vertex.
testCases{
{
op: polyclip.UNION,
subject: polyclip.Polygon{
{{0, 6}, {5, 5}, {2, 10}},
{{4, 0}, {10, 4}, {5, 5}},
},
clipping: polyclip.Polygon{
{{5, 5}, {10, 8}, {8, 10}},
},
result: polyclip.Polygon{{
{0, 6}, {5, 5}, {4, 0}, {10, 4}, {5, 5}, {10, 8}, {8, 10}, {5, 5}, {2, 10},
}},
},
{
// With vertical edges
op: polyclip.UNION,
subject: polyclip.Polygon{
{{0, 6}, {5, 5}, {5, 10}},
{{5, 0}, {10, 4}, {5, 5}},
},
clipping: polyclip.Polygon{
{{5, 5}, {10, 8}, {8, 10}},
},
result: polyclip.Polygon{{
{0, 6}, {5, 5}, {5, 0}, {10, 4}, {5, 5}, {10, 8}, {8, 10}, {5, 5}, {5, 10},
}},
},
{
// First triangle to the left of the other two
op: polyclip.UNION,
subject: polyclip.Polygon{
{{0, 6}, {5, 5}, {2, 10}},
{{6, 0}, {10, 4}, {5, 5}},
},
clipping: polyclip.Polygon{
{{5, 5}, {10, 8}, {8, 10}},
},
result: polyclip.Polygon{
{{0, 6}, {5, 5}, {2, 10}},
{{5, 5}, {10, 4}, {6, 0}, {5, 5}, {8, 10}, {10, 8}},
},
},
}.verify(t)
}

func TestNonReductiveSegmentDivisions(t *testing.T) {
if testing.Short() {
return
Expand Down Expand Up @@ -868,3 +1064,102 @@ func TestInfiniteLoopBug(t *testing.T) {
t.Errorf("expected:\n%v\ngot:\n%v", dump(want), dump(result))
}
}

type testCaseMakeValid struct {
name string
poly polyclip.Polygon
result polyclip.Polygon
}

type testCasesMakeValid []testCaseMakeValid

func (cases testCasesMakeValid) verify(t *testing.T) {
t.Helper()
for _, c := range cases {
t.Run(c.name, func(t *testing.T) {
result := dump(c.poly.MakeValid())
if result != dump(c.result) {
t.Errorf("%s:\npolygon: %v\nexpected: %v\ngot: %v",
c.name, c.poly, c.result, result)
}
})
}
}

func TestMakeValid(t *testing.T) {
testCasesMakeValid{
{
name: "Self-intersecting polygon",
poly: polyclip.Polygon{{{0, 0}, {1, 1}, {1, 0}, {0, 1}}},
result: polyclip.Polygon{
{{0, 0}, {0.5, 0.5}, {0, 1}},
{{0.5, 0.5}, {1, 1}, {1, 0}},
},
},
{
name: "Polygon with repeated vertical edge",
poly: polyclip.Polygon{{{0, 0}, {1, 0}, {1, 1}, {2, 1}, {2, 0}, {1, 0},
{1, 1}, {0, 1}}},
result: polyclip.Polygon{{{0, 0}, {1, 0}, {2, 0}, {2, 1}, {1, 1}, {0, 1}}},
},
{
name: "Polygon with repeated horizontal edge",
poly: polyclip.Polygon{{{0, 0}, {1, 0}, {1, 1}, {0, 1}, {0, 2}, {1, 2},
{1, 1}, {0, 1}}},
result: polyclip.Polygon{{{0, 0}, {1, 0}, {1, 1}, {1, 2}, {0, 2}, {0, 1}}},
},
{
name: "Polygon with repeated dangling edge 1",
poly: polyclip.Polygon{{{0, 0}, {1, 0}, {0, 0}, {1, 0}, {1, 1}, {0, 1}}},
result: polyclip.Polygon{{{0, 0}, {1, 0}, {1, 1}, {0, 1}}},
},
{
name: "Polygon with repeated dangling edge 2",
poly: polyclip.Polygon{{{0, 0}, {1, 0}, {1, 1}, {1, 0}, {1, 1}, {0, 1}}},
result: polyclip.Polygon{{{0, 0}, {1, 0}, {1, 1}, {0, 1}}},
},
{
name: "Polygon with repeated dangling edge 3",
poly: polyclip.Polygon{{{0, 0}, {1, 0}, {1, 1}, {0, 1}, {1, 1}, {0, 1}}},
result: polyclip.Polygon{{{0, 0}, {1, 0}, {1, 1}, {0, 1}}},
},
{
name: "Polygon with repeated dangling edge 4",
poly: polyclip.Polygon{{{0, 0}, {1, 0}, {1, 1}, {0, 1}, {0, 0}, {0, 1}}},
result: polyclip.Polygon{{{0, 0}, {1, 0}, {1, 1}, {0, 1}}},
},
{
name: "Polygon with partially repeated edge",
poly: polyclip.Polygon{{{0, 0}, {1, 0}, {1, 0.75}, {2, 0.75}, {2, 0.25}, {1, 0.25},
{1, 1}, {0, 1}}},
result: polyclip.Polygon{{{0, 0}, {1, 0}, {1, 0.25}, {2, 0.25}, {2, 0.75},
{1, 0.75}, {1, 1}, {0, 1}}},
},
{
name: "Polygon with repeated edge in opposite direction",
poly: polyclip.Polygon{
{{0, 0}, {1, 0}, {1, 1}, {0, 1}},
{{1, 0}, {2, 0}, {2, 1}, {1, 1}},
},
result: polyclip.Polygon{
{{0, 0}, {1, 0}, {2, 0}, {2, 1}, {1, 1}, {0, 1}},
},
},
{
name: "Polygon with partially repeated edge in opposite direction",
poly: polyclip.Polygon{
{{0, 0}, {1, 0}, {1, 1}, {0, 1}},
{{1, 0.25}, {2, 0.25}, {2, 0.75}, {1, 0.75}},
},
result: polyclip.Polygon{
{{0, 0}, {1, 0}, {1, 0.25}, {2, 0.25},
{2, 0.75}, {1, 0.75}, {1, 1}, {0, 1}},
},
},
{
name: "Completely degenerate",
poly: polyclip.Polygon{{{1, 2}, {2, 2}, {2, 3}, {1, 2}, {2, 2}, {2, 3}}},
result: polyclip.Polygon{},
},
}.verify(t)
}
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