60 lines
1.2 KiB
Go
60 lines
1.2 KiB
Go
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package gg
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import "math"
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func quadratic(x0, y0, x1, y1, x2, y2, t float64) (x, y float64) {
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u := 1 - t
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a := u * u
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b := 2 * u * t
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c := t * t
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x = a*x0 + b*x1 + c*x2
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y = a*y0 + b*y1 + c*y2
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return
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}
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func QuadraticBezier(x0, y0, x1, y1, x2, y2 float64) []Point {
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l := (math.Hypot(x1-x0, y1-y0) +
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math.Hypot(x2-x1, y2-y1))
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n := int(l + 0.5)
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if n < 4 {
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n = 4
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}
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d := float64(n) - 1
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result := make([]Point, n)
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for i := 0; i < n; i++ {
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t := float64(i) / d
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x, y := quadratic(x0, y0, x1, y1, x2, y2, t)
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result[i] = Point{x, y}
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}
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return result
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}
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func cubic(x0, y0, x1, y1, x2, y2, x3, y3, t float64) (x, y float64) {
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u := 1 - t
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a := u * u * u
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b := 3 * u * u * t
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c := 3 * u * t * t
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d := t * t * t
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x = a*x0 + b*x1 + c*x2 + d*x3
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y = a*y0 + b*y1 + c*y2 + d*y3
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return
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}
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func CubicBezier(x0, y0, x1, y1, x2, y2, x3, y3 float64) []Point {
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l := (math.Hypot(x1-x0, y1-y0) +
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math.Hypot(x2-x1, y2-y1) +
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math.Hypot(x3-x2, y3-y2))
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n := int(l + 0.5)
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if n < 4 {
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n = 4
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}
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d := float64(n) - 1
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result := make([]Point, n)
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for i := 0; i < n; i++ {
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t := float64(i) / d
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x, y := cubic(x0, y0, x1, y1, x2, y2, x3, y3, t)
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result[i] = Point{x, y}
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}
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return result
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}
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