Data commit

Task/Brownian-tree/Go/brownian-tree-1.go

@@ -0,0 +1,85 @@
+package main
+
+import (
+    "fmt"
+    "image"
+    "image/color"
+    "image/png"
+    "math/rand"
+    "os"
+)
+
+const w = 400     // image width
+const h = 300     // image height
+const n = 15000   // number of particles to add
+const frost = 255 // white
+
+var g *image.Gray
+
+func main() {
+    g = image.NewGray(image.Rectangle{image.Point{0, 0}, image.Point{w, h}})
+    // off center seed position makes pleasingly asymetrical tree
+    g.SetGray(w/3, h/3, color.Gray{frost})
+generate:
+    for a := 0; a < n; {
+        // generate random position for new particle
+        rp := image.Point{rand.Intn(w), rand.Intn(h)}
+        if g.At(rp.X, rp.Y).(color.Gray).Y == frost {
+            // position is already set.  find a nearby free position.
+            for {
+                rp.X += rand.Intn(3) - 1
+                rp.Y += rand.Intn(3) - 1
+                // execpt if we run out of bounds, consider the particle lost.
+                if !rp.In(g.Rect) {
+                    continue generate
+                }
+                if g.At(rp.X, rp.Y).(color.Gray).Y != frost {
+                    break
+                }
+            }
+        } else {
+            // else particle is in free space.  let it wander
+            // until it touches tree
+            for !hasNeighbor(rp) {
+                rp.X += rand.Intn(3) - 1
+                rp.Y += rand.Intn(3) - 1
+                // but again, if it wanders out of bounds consider it lost.
+                if !rp.In(g.Rect) {
+                    continue generate
+                }
+            }
+        }
+        // x, y now specify a free position toucing the tree.
+        g.SetGray(rp.X, rp.Y, color.Gray{frost})
+        a++
+        // progress indicator
+        if a%100 == 0 {
+            fmt.Println(a, "of", n)
+        }
+    }
+    f, err := os.Create("tree.png")
+    if err != nil {
+        fmt.Println(err)
+        return
+    }
+    err = png.Encode(f, g)
+    if err != nil {
+        fmt.Println(err)
+    }
+    f.Close()
+}
+
+var n8 = []image.Point{
+    {-1, -1}, {-1, 0}, {-1, 1},
+    {0, -1}, {0, 1},
+    {1, -1}, {1, 0}, {1, 1}}
+
+func hasNeighbor(p image.Point) bool {
+    for _, n := range n8 {
+        o := p.Add(n)
+        if o.In(g.Rect) && g.At(o.X, o.Y).(color.Gray).Y == frost {
+            return true
+        }
+    }
+    return false
+}

Task/Brownian-tree/Go/brownian-tree-2.go

@@ -0,0 +1,79 @@
+package main
+
+// Files required to build supporting package raster are found in:
+// * Bitmap
+// * Grayscale image
+// * Write a PPM file
+
+import (
+    "fmt"
+    "math/rand"
+    "raster"
+)
+
+const w = 400       // image width
+const h = 300       // image height
+const n = 15000     // number of particles to add
+const frost = 65535 // white
+
+var g *raster.Grmap
+
+func main() {
+    g = raster.NewGrmap(w, h)
+    // off center seed position makes pleasingly asymetrical tree
+    g.SetPx(w/3, h/3, frost)
+    var x, y int
+generate:
+    for a := 0; a < n; {
+        // generate random position for new particle
+        x, y = rand.Intn(w), rand.Intn(h)
+        switch p, ok := g.GetPx(x, y); p {
+        case frost:
+            // position is already set.  find a nearby free position.
+            for p == frost {
+                x += rand.Intn(3) - 1
+                y += rand.Intn(3) - 1
+                p, ok = g.GetPx(x, y)
+
+                // execpt if we run out of bounds, consider the particle lost.
+                if !ok {
+                    continue generate
+                }
+            }
+        default:
+            // else particle is in free space.  let it wander
+            // until it touches tree
+            for !hasNeighbor(x, y) {
+                x += rand.Intn(3) - 1
+                y += rand.Intn(3) - 1
+                // but again, if it wanders out of bounds consider it lost.
+                _, ok = g.GetPx(x, y)
+                if !ok {
+                    continue generate
+                }
+            }
+        }
+        // x, y now specify a free position toucing the tree.
+        g.SetPx(x, y, frost)
+        a++
+        // progress indicator
+        if a%100 == 0 {
+            fmt.Println(a, "of", n)
+        }
+    }
+    g.Bitmap().WritePpmFile("tree.ppm")
+}
+
+var n8 = [][]int{
+    {-1, -1}, {-1, 0}, {-1, 1},
+    { 0, -1},          { 0, 1},
+    { 1, -1}, { 1, 0}, { 1, 1}}
+
+func hasNeighbor(x, y int) bool {
+    for _, n := range n8 {
+        if p, ok := g.GetPx(x+n[0], y+n[1]); ok && p == frost {
+            return true
+        }
+    }
+    return false
+}