move flattening code in draw2dbase
This commit is contained in:
Laurent Le Goff
parent
82ef300f1d
commit
74e6b9b1ec
161
curve.go
161
curve.go
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@ -1,161 +0,0 @@
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// Copyright 2010 The draw2d Authors. All rights reserved.
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// created: 17/05/2011 by Laurent Le Goff
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package draw2d
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import (
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"math"
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)
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const (
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CurveRecursionLimit = 32
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)
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// Cubic
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// x1, y1, cpx1, cpy1, cpx2, cpy2, x2, y2 float64
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// Subdivide a Bezier cubic curve in 2 equivalents Bezier cubic curves.
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// c1 and c2 parameters are the resulting curves
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func SubdivideCubic(c, c1, c2 []float64) {
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// First point of c is the first point of c1
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c1[0], c1[1] = c[0], c[1]
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// Last point of c is the last point of c2
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c2[6], c2[7] = c[6], c[7]
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// Subdivide segment using midpoints
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c1[2] = (c[0] + c[2]) / 2
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c1[3] = (c[1] + c[3]) / 2
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midX := (c[2] + c[4]) / 2
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midY := (c[3] + c[5]) / 2
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c2[4] = (c[4] + c[6]) / 2
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c2[5] = (c[5] + c[7]) / 2
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c1[4] = (c1[2] + midX) / 2
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c1[5] = (c1[3] + midY) / 2
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c2[2] = (midX + c2[4]) / 2
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c2[3] = (midY + c2[5]) / 2
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c1[6] = (c1[4] + c2[2]) / 2
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c1[7] = (c1[5] + c2[3]) / 2
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// Last Point of c1 is equal to the first point of c2
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c2[0], c2[1] = c1[6], c1[7]
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}
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// TraceCubic generate lines subdividing the cubic curve using a Flattener
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// flattening_threshold helps determines the flattening expectation of the curve
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func TraceCubic(t Flattener, cubic []float64, flattening_threshold float64) {
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// Allocation curves
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var curves [CurveRecursionLimit * 8]float64
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copy(curves[0:8], cubic[0:8])
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i := 0
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// current curve
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var c []float64
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var dx, dy, d2, d3 float64
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for i >= 0 {
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c = curves[i*8:]
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dx = c[6] - c[0]
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dy = c[7] - c[1]
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d2 = math.Abs((c[2]-c[6])*dy - (c[3]-c[7])*dx)
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d3 = math.Abs((c[4]-c[6])*dy - (c[5]-c[7])*dx)
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// if it's flat then trace a line
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if (d2+d3)*(d2+d3) < flattening_threshold*(dx*dx+dy*dy) || i == len(curves)-1 {
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t.LineTo(c[6], c[7])
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i--
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} else {
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// second half of bezier go lower onto the stack
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SubdivideCubic(c, curves[(i+1)*8:], curves[i*8:])
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i++
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}
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}
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}
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// Quad
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// x1, y1, cpx1, cpy2, x2, y2 float64
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// Subdivide a Bezier quad curve in 2 equivalents Bezier quad curves.
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// c1 and c2 parameters are the resulting curves
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func SubdivideQuad(c, c1, c2 []float64) {
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// First point of c is the first point of c1
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c1[0], c1[1] = c[0], c[1]
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// Last point of c is the last point of c2
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c2[4], c2[5] = c[4], c[5]
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// Subdivide segment using midpoints
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c1[2] = (c[0] + c[2]) / 2
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c1[3] = (c[1] + c[3]) / 2
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c2[2] = (c[2] + c[4]) / 2
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c2[3] = (c[3] + c[5]) / 2
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c1[4] = (c1[2] + c2[2]) / 2
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c1[5] = (c1[3] + c2[3]) / 2
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c2[0], c2[1] = c1[4], c1[5]
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return
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}
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// Trace generate lines subdividing the curve using a Flattener
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// flattening_threshold helps determines the flattening expectation of the curve
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func TraceQuad(t Flattener, quad []float64, flattening_threshold float64) {
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// Allocates curves stack
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var curves [CurveRecursionLimit * 6]float64
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copy(curves[0:6], quad[0:6])
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i := 0
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// current curve
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var c []float64
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var dx, dy, d float64
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for i >= 0 {
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c = curves[i*6:]
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dx = c[4] - c[0]
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dy = c[5] - c[1]
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d = math.Abs(((c[2]-c[4])*dy - (c[3]-c[5])*dx))
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// if it's flat then trace a line
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if (d*d) < flattening_threshold*(dx*dx+dy*dy) || i == len(curves)-1 {
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t.LineTo(c[4], c[5])
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i--
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} else {
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// second half of bezier go lower onto the stack
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SubdivideQuad(c, curves[(i+1)*6:], curves[i*6:])
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i++
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}
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}
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}
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// TraceArc trace an arc using a Flattener
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func TraceArc(t Flattener, x, y, rx, ry, start, angle, scale float64) (lastX, lastY float64) {
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end := start + angle
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clockWise := true
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if angle < 0 {
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clockWise = false
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}
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ra := (math.Abs(rx) + math.Abs(ry)) / 2
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da := math.Acos(ra/(ra+0.125/scale)) * 2
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//normalize
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if !clockWise {
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da = -da
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}
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angle = start + da
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var curX, curY float64
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for {
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if (angle < end-da/4) != clockWise {
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curX = x + math.Cos(end)*rx
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curY = y + math.Sin(end)*ry
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return curX, curY
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}
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curX = x + math.Cos(angle)*rx
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curY = y + math.Sin(angle)*ry
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angle += da
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t.LineTo(curX, curY)
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}
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return curX, curY
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}
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136
curve_test.go
136
curve_test.go
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@ -1,136 +0,0 @@
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package draw2d
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import (
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"bufio"
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"fmt"
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"image"
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"image/color"
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"image/draw"
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"image/png"
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"log"
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"os"
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"testing"
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"github.com/llgcode/draw2d/raster"
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)
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var (
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flattening_threshold float64 = 0.5
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testsCubicFloat64 = []float64{
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100, 100, 200, 100, 100, 200, 200, 200,
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100, 100, 300, 200, 200, 200, 300, 100,
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100, 100, 0, 300, 200, 0, 300, 300,
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150, 290, 10, 10, 290, 10, 150, 290,
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10, 290, 10, 10, 290, 10, 290, 290,
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100, 290, 290, 10, 10, 10, 200, 290,
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}
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testsQuadFloat64 = []float64{
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100, 100, 200, 100, 200, 200,
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100, 100, 290, 200, 290, 100,
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100, 100, 0, 290, 200, 290,
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150, 290, 10, 10, 290, 290,
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10, 290, 10, 10, 290, 290,
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100, 290, 290, 10, 120, 290,
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}
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)
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func init() {
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os.Mkdir("test_results", 0666)
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f, err := os.Create("test_results/_test.html")
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if err != nil {
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log.Println(err)
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os.Exit(1)
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}
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defer f.Close()
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log.Printf("Create html viewer")
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f.Write([]byte("<html><body>"))
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for i := 0; i < len(testsCubicFloat64)/8; i++ {
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f.Write([]byte(fmt.Sprintf("<div><img src='_test%d.png'/></div>\n", i)))
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}
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for i := 0; i < len(testsQuadFloat64); i++ {
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f.Write([]byte(fmt.Sprintf("<div><img src='_testQuad%d.png'/>\n</div>\n", i)))
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}
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f.Write([]byte("</body></html>"))
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}
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func drawPoints(img draw.Image, c color.Color, s ...float64) image.Image {
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for i := 0; i < len(s); i += 2 {
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x, y := int(s[i]+0.5), int(s[i+1]+0.5)
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img.Set(x, y, c)
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img.Set(x, y+1, c)
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img.Set(x, y-1, c)
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img.Set(x+1, y, c)
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img.Set(x+1, y+1, c)
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img.Set(x+1, y-1, c)
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img.Set(x-1, y, c)
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img.Set(x-1, y+1, c)
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img.Set(x-1, y-1, c)
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}
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return img
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}
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func TestCubicCurve(t *testing.T) {
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for i := 0; i < len(testsCubicFloat64); i += 8 {
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var p SegmentedPath
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p.MoveTo(testsCubicFloat64[i], testsCubicFloat64[i+1])
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TraceCubic(&p, testsCubicFloat64[i:], flattening_threshold)
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img := image.NewNRGBA(image.Rect(0, 0, 300, 300))
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raster.PolylineBresenham(img, color.NRGBA{0xff, 0, 0, 0xff}, testsCubicFloat64[i:i+8]...)
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raster.PolylineBresenham(img, image.Black, p.Points...)
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//drawPoints(img, image.NRGBAColor{0, 0, 0, 0xff}, curve[:]...)
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drawPoints(img, color.NRGBA{0, 0, 0, 0xff}, p.Points...)
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SaveToPngFile(fmt.Sprintf("test_results/_test%d.png", i/8), img)
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log.Printf("Num of points: %d\n", len(p.Points))
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}
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fmt.Println()
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}
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func TestQuadCurve(t *testing.T) {
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for i := 0; i < len(testsQuadFloat64); i += 6 {
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var p SegmentedPath
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p.MoveTo(testsQuadFloat64[i], testsQuadFloat64[i+1])
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TraceQuad(&p, testsQuadFloat64[i:], flattening_threshold)
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img := image.NewNRGBA(image.Rect(0, 0, 300, 300))
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raster.PolylineBresenham(img, color.NRGBA{0xff, 0, 0, 0xff}, testsQuadFloat64[i:i+6]...)
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raster.PolylineBresenham(img, image.Black, p.Points...)
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//drawPoints(img, image.NRGBAColor{0, 0, 0, 0xff}, curve[:]...)
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drawPoints(img, color.NRGBA{0, 0, 0, 0xff}, p.Points...)
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SaveToPngFile(fmt.Sprintf("test_results/_testQuad%d.png", i), img)
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log.Printf("Num of points: %d\n", len(p.Points))
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}
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fmt.Println()
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}
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func BenchmarkCubicCurve(b *testing.B) {
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for i := 0; i < b.N; i++ {
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for i := 0; i < len(testsCubicFloat64); i += 8 {
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var p SegmentedPath
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p.MoveTo(testsCubicFloat64[i], testsCubicFloat64[i+1])
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TraceCubic(&p, testsCubicFloat64[i:], flattening_threshold)
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}
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}
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}
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// SaveToPngFile create and save an image to a file using PNG format
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func SaveToPngFile(filePath string, m image.Image) error {
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// Create the file
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f, err := os.Create(filePath)
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if err != nil {
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return err
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}
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defer f.Close()
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// Create Writer from file
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b := bufio.NewWriter(f)
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// Write the image into the buffer
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err = png.Encode(b, m)
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if err != nil {
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return err
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}
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err = b.Flush()
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if err != nil {
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return err
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}
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return nil
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}
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