59 lines
977 B
Go
59 lines
977 B
Go
// Copyright 2011 The draw2d Authors. All rights reserved.
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// created: 27/05/2011 by Laurent Le Goff
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package draw2dbase
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import (
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"image/color"
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"image/draw"
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)
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func abs(i int) int {
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if i < 0 {
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return -i
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}
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return i
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}
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// PolylineBresenham draws a polyline to an image
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func PolylineBresenham(img draw.Image, c color.Color, s ...float64) {
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for i := 2; i < len(s); i += 2 {
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Bresenham(img, c, int(s[i-2]+0.5), int(s[i-1]+0.5), int(s[i]+0.5), int(s[i+1]+0.5))
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}
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}
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// Bresenham draws a line between (x0, y0) and (x1, y1)
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func Bresenham(img draw.Image, color color.Color, x0, y0, x1, y1 int) {
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dx := abs(x1 - x0)
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dy := abs(y1 - y0)
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var sx, sy int
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if x0 < x1 {
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sx = 1
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} else {
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sx = -1
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}
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if y0 < y1 {
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sy = 1
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} else {
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sy = -1
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}
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err := dx - dy
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var e2 int
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for {
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img.Set(x0, y0, color)
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if x0 == x1 && y0 == y1 {
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return
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}
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e2 = 2 * err
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if e2 > -dy {
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err = err - dy
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x0 = x0 + sx
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}
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if e2 < dx {
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err = err + dx
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y0 = y0 + sy
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}
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}
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}
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