86 lines
2.1 KiB
Go
86 lines
2.1 KiB
Go
package main
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import (
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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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)
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const (
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width, height = 800, 600
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maxDepth = 11 // how far to recurse, between 1 and 20 is reasonable
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colFactor = uint8(255 / maxDepth) // adjusts the colour so leaves get greener further out
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fileName = "pythagorasTree.png"
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)
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func main() {
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img := image.NewNRGBA(image.Rect(0, 0, width, height)) // create new image
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bg := image.NewUniform(color.RGBA{255, 255, 255, 255}) // prepare white for background
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draw.Draw(img, img.Bounds(), bg, image.ZP, draw.Src) // fill the background
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drawSquares(340, 550, 460, 550, img, 0) // start off near the bottom of the image
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imgFile, err := os.Create(fileName)
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if err != nil {
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log.Fatal(err)
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}
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defer imgFile.Close()
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if err := png.Encode(imgFile, img); err != nil {
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imgFile.Close()
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log.Fatal(err)
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}
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}
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func drawSquares(ax, ay, bx, by int, img *image.NRGBA, depth int) {
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if depth > maxDepth {
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return
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}
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dx, dy := bx-ax, ay-by
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x3, y3 := bx-dy, by-dx
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x4, y4 := ax-dy, ay-dx
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x5, y5 := x4+(dx-dy)/2, y4-(dx+dy)/2
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col := color.RGBA{0, uint8(depth) * colFactor, 0, 255}
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drawLine(ax, ay, bx, by, img, col)
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drawLine(bx, by, x3, y3, img, col)
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drawLine(x3, y3, x4, y4, img, col)
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drawLine(x4, y4, ax, ay, img, col)
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drawSquares(x4, y4, x5, y5, img, depth+1)
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drawSquares(x5, y5, x3, y3, img, depth+1)
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}
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func drawLine(x0, y0, x1, y1 int, img *image.NRGBA, col color.RGBA) {
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dx := abs(x1 - x0)
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dy := abs(y1 - y0)
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var sx, sy int = -1, -1
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if x0 < x1 {
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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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}
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err := dx - dy
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for {
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img.Set(x0, y0, col)
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if x0 == x1 && y0 == y1 {
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break
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}
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e2 := 2 * err
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if e2 > -dy {
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err -= dy
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x0 += sx
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}
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if e2 < dx {
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err += dx
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y0 += sy
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}
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}
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}
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func abs(x int) int {
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if x < 0 {
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return -x
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}
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return x
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}
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