mirror of https://github.com/tidwall/tile38.git
109 lines
2.1 KiB
Go
109 lines
2.1 KiB
Go
// Package poly provides polygon detection methods.
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package poly
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import "fmt"
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// Point is simple 2D point
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type Point struct {
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X, Y, Z float64
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}
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// InsideRect detects point is inside of another rect
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func (p Point) InsideRect(rect Rect) bool {
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if p.X < rect.Min.X || p.X > rect.Max.X {
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return false
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}
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if p.Y < rect.Min.Y || p.Y > rect.Max.Y {
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return false
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}
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return true
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}
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// Polygon is series of points that make up a polygon
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type Polygon []Point
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// InsideRect detects polygon is inside of another rect
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func (p Polygon) InsideRect(rect Rect) bool {
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if len(p) == 0 {
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return false
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}
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for _, p := range p {
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if !p.InsideRect(rect) {
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return false
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}
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}
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return true
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}
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// IntersectsRect detects polygon is inside of another rect
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func (p Polygon) IntersectsRect(rect Rect) bool {
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if len(p) == 0 {
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return false
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}
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rectPoly := Polygon{rect.Min, {rect.Min.X, rect.Max.Y, 0}, rect.Max, {rect.Max.X, rect.Min.Y, 0}, rect.Min}
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return p.Intersects(rectPoly, nil)
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}
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// String returns a string representation of the polygon.
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func (p Polygon) String() string {
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s := "{"
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for i, p := range p {
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if i > 0 {
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s += ", "
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}
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s += fmt.Sprintf("{%v, %v}", p.X, p.Y)
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}
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s += "}"
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return s
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}
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// Rect is rectangle
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type Rect struct {
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Min, Max Point
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}
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// Rect returns the bounding box rectangle for the polygon
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func (p Polygon) Rect() Rect {
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var bbox Rect
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for i, p := range p {
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if i == 0 {
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bbox.Min = p
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bbox.Max = p
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} else {
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if p.X < bbox.Min.X {
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bbox.Min.X = p.X
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} else if p.X > bbox.Max.X {
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bbox.Max.X = p.X
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}
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if p.Y < bbox.Min.Y {
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bbox.Min.Y = p.Y
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} else if p.Y > bbox.Max.Y {
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bbox.Max.Y = p.Y
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}
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}
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}
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return bbox
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}
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// IntersectsRect detects if two bboxes intersect.
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func (r Rect) IntersectsRect(rect Rect) bool {
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if r.Min.Y > rect.Max.Y || r.Max.Y < rect.Min.Y {
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return false
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}
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if r.Min.X > rect.Max.X || r.Max.X < rect.Min.X {
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return false
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}
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return true
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}
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// InsideRect detects rect is inside of another rect
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func (r Rect) InsideRect(rect Rect) bool {
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if r.Min.X < rect.Min.X || r.Max.X > rect.Max.X {
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return false
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}
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if r.Min.Y < rect.Min.Y || r.Max.Y > rect.Max.Y {
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return false
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}
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return true
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}
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