69 lines
1.3 KiB
Go
69 lines
1.3 KiB
Go
package mx
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// The type represents a line segment. The name is for short.
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type Line [2]Vector
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type Lines []Line
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// Returns corresponding to the segment Line.
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func (l Line) GetLineExpr() LineExpr {
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var (
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x Float
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vertical bool
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)
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p0 := l[0]
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p1 := l[1]
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k := (p0.Y - p1.Y) / (p0.X - p1.X)
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c := p0.Y - p0.X*k
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if p0.X == p1.X {
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x = p0.X
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vertical = true
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}
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return LineExpr{k, c, x, vertical}
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}
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// Returns the points that the Line contains.
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func (l Line) GetContainedPoints(pts Vectors) Vectors {
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ret := make(Vectors, 0, len(pts))
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for i := range pts {
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if l.ContainsPoint(pts[i]) {
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ret = append(ret, pts[i])
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}
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}
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return ret
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}
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// Check if the edge contains the specified point.
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func (l Line) ContainsPoint(p Vector) bool {
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lexpr := l.GetLineExpr()
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if !lexpr.ContainsPoint(p) {
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return false
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}
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xMax := Max(l[0].X, l[1].X)
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xMin := Min(l[0].X, l[1].X)
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yMax := Max(l[0].Y, l[1].Y)
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yMin := Min(l[0].Y, l[1].Y)
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if !(xMin <= p.X && p.X <= xMax) ||
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!(yMin <= p.Y && p.Y <= yMax) {
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return false
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}
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return true
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}
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// Get square of length of line segment (for performance sometimes).
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func (ls Line) LenSqr() Float {
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return Sqr(ls[0].X - ls[1].X) +
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Sqr(ls[0].Y - ls[1].Y)
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}
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// Get length of the line segment.
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func (ls Line) Len() Float {
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return Sqrt(ls.LenSqr())
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}
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