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// Copyright 2010 The draw2d Authors. All rights reserved.
// created: 21/11/2010 by Laurent Le Goff
package draw2d
import (
"code.google.com/p/freetype-go/freetype/raster"
"math"
)
func arc(t VertexConverter, x, y, rx, ry, start, angle, scale float64) (lastX, lastY float64) {
end := start + angle
clockWise := true
if angle < 0 {
clockWise = false
}
ra := (math.Abs(rx) + math.Abs(ry)) / 2
da := math.Acos(ra/(ra+0.125/scale)) * 2
//normalize
if !clockWise {
da = -da
}
angle = start + da
var curX, curY float64
for {
if (angle < end-da/4) != clockWise {
curX = x + math.Cos(end)*rx
curY = y + math.Sin(end)*ry
return curX, curY
}
curX = x + math.Cos(angle)*rx
curY = y + math.Sin(angle)*ry
angle += da
t.Vertex(curX, curY)
}
return curX, curY
}
func arcAdder(adder raster.Adder, x, y, rx, ry, start, angle, scale float64) raster.Point {
end := start + angle
clockWise := true
if angle < 0 {
clockWise = false
}
ra := (math.Abs(rx) + math.Abs(ry)) / 2
da := math.Acos(ra/(ra+0.125/scale)) * 2
//normalize
if !clockWise {
da = -da
}
angle = start + da
var curX, curY float64
for {
if (angle < end-da/4) != clockWise {
curX = x + math.Cos(end)*rx
curY = y + math.Sin(end)*ry
return raster.Point{raster.Fix32(curX * 256), raster.Fix32(curY * 256)}
}
curX = x + math.Cos(angle)*rx
curY = y + math.Sin(angle)*ry
angle += da
adder.Add1(raster.Point{raster.Fix32(curX * 256), raster.Fix32(curY * 256)})
}
return raster.Point{raster.Fix32(curX * 256), raster.Fix32(curY * 256)}
}
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