Initial data commit

Task/Plasma-effect/Go/plasma-effect.go

@@ -0,0 +1,89 @@
+package main
+
+import (
+    "image"
+    "image/color"
+    "image/gif"
+    "log"
+    "math"
+    "os"
+)
+
+func setBackgroundColor(img *image.Paletted, w, h int, ci uint8) {
+    for x := 0; x < w; x++ {
+        for y := 0; y < h; y++ {
+            img.SetColorIndex(x, y, ci)
+        }
+    }
+}
+
+func hsb2rgb(hue, sat, bri float64) (r, g, b int) {
+    u := int(bri*255 + 0.5)
+    if sat == 0 {
+        r, g, b = u, u, u
+    } else {
+        h := (hue - math.Floor(hue)) * 6
+        f := h - math.Floor(h)
+        p := int(bri*(1-sat)*255 + 0.5)
+        q := int(bri*(1-sat*f)*255 + 0.5)
+        t := int(bri*(1-sat*(1-f))*255 + 0.5)
+        switch int(h) {
+        case 0:
+            r, g, b = u, t, p
+        case 1:
+            r, g, b = q, u, p
+        case 2:
+            r, g, b = p, u, t
+        case 3:
+            r, g, b = p, q, u
+        case 4:
+            r, g, b = t, p, u
+        case 5:
+            r, g, b = u, p, q
+        }
+    }
+    return
+}
+
+func main() {
+    const degToRad = math.Pi / 180
+    const nframes = 100
+    const delay = 4 // 40ms
+    w, h := 640, 640
+    anim := gif.GIF{LoopCount: nframes}
+    rect := image.Rect(0, 0, w, h)
+    palette := make([]color.Color, nframes+1)
+    palette[0] = color.White
+    for i := 1; i <= nframes; i++ {
+        r, g, b := hsb2rgb(float64(i)/nframes, 1, 1)
+        palette[i] = color.RGBA{uint8(r), uint8(g), uint8(b), 255}
+    }
+    for f := 1; f <= nframes; f++ {
+        img := image.NewPaletted(rect, palette)
+        setBackgroundColor(img, w, h, 0) // white background
+        for y := 0; y < h; y++ {
+            for x := 0; x < w; x++ {
+                fx, fy := float64(x), float64(y)
+                value := math.Sin(fx / 16)
+                value += math.Sin(fy / 8)
+                value += math.Sin((fx + fy) / 16)
+                value += math.Sin(math.Sqrt(fx*fx+fy*fy) / 8)
+                value += 4 // shift range from [-4, 4] to [0, 8]
+                value /= 8 // bring range down to [0, 1]
+                _, rem := math.Modf(value + float64(f)/float64(nframes))
+                ci := uint8(nframes*rem) + 1
+                img.SetColorIndex(x, y, ci)
+            }
+        }
+        anim.Delay = append(anim.Delay, delay)
+        anim.Image = append(anim.Image, img)
+    }
+    file, err := os.Create("plasma.gif")
+    if err != nil {
+        log.Fatal(err)
+    }
+    defer file.Close()
+    if err2 := gif.EncodeAll(file, &anim); err != nil {
+        log.Fatal(err2)
+    }
+}