52 lines
1.2 KiB
Go
52 lines
1.2 KiB
Go
// Copyright 2010 The draw2d Authors. All rights reserved.
|
|
// created: 17/05/2011 by Laurent Le Goff
|
|
package curve
|
|
|
|
import (
|
|
"math"
|
|
)
|
|
|
|
//X1, Y1, X2, Y2, X3, Y3 float64
|
|
type QuadCurveFloat64 [6]float64
|
|
|
|
func (c *QuadCurveFloat64) Subdivide(c1, c2 *QuadCurveFloat64) {
|
|
// Calculate all the mid-points of the line segments
|
|
//----------------------
|
|
c1[0], c1[1] = c[0], c[1]
|
|
c2[4], c2[5] = c[4], c[5]
|
|
c1[2] = (c[0] + c[2]) / 2
|
|
c1[3] = (c[1] + c[3]) / 2
|
|
c2[2] = (c[2] + c[4]) / 2
|
|
c2[3] = (c[3] + c[5]) / 2
|
|
c1[4] = (c1[2] + c2[2]) / 2
|
|
c1[5] = (c1[3] + c2[3]) / 2
|
|
c2[0], c2[1] = c1[4], c1[5]
|
|
return
|
|
}
|
|
|
|
func (curve *QuadCurveFloat64) Segment(t LineTracer, flattening_threshold float64) {
|
|
var curves [CurveRecursionLimit]QuadCurveFloat64
|
|
curves[0] = *curve
|
|
i := 0
|
|
// current curve
|
|
var c *QuadCurveFloat64
|
|
var dx, dy, d float64
|
|
|
|
for i >= 0 {
|
|
c = &curves[i]
|
|
dx = c[4] - c[0]
|
|
dy = c[5] - c[1]
|
|
|
|
d = math.Abs(((c[2]-c[4])*dy - (c[3]-c[5])*dx))
|
|
|
|
if (d*d) < flattening_threshold*(dx*dx+dy*dy) || i == len(curves)-1 {
|
|
t.LineTo(c[4], c[5])
|
|
i--
|
|
} else {
|
|
// second half of bezier go lower onto the stack
|
|
c.Subdivide(&curves[i+1], &curves[i])
|
|
i++
|
|
}
|
|
}
|
|
}
|