/
chaos.go
140 lines (124 loc) · 3.16 KB
/
chaos.go
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package superfractal
import (
. "fmt"
"math/rand"
"strings"
"unicode"
"github.com/strickyak/canvas"
)
const SKIP = 32
type Affine struct {
A, B, C, D, E, F float64
}
type IFS struct {
Choices []*Affine
}
// Apply the Affine function once, to floats x,y, and return 2 new floats.
func (o Affine) Apply(x, y float64) (float64, float64) {
ax := x*o.A + y*o.B + o.E
ay := x*o.C + y*o.D + o.F
return ax, ay
}
// ChaosGame steps SKIP+n times, plotting the last n points.
func (o IFS) ChaosGame(targ *canvas.Canvas, n int, c canvas.Color) {
x, y := 0.5, 0.5
for i := 0; i < SKIP; i++ {
x, y = o.Choose().Apply(x, y)
}
for i := 0; i < n; i++ {
x, y = o.Choose().Apply(x, y)
targ.FSet(x, y, c)
}
}
// WholeGame
func (o IFS) WholeGame(src *canvas.Canvas, n int) *canvas.Canvas {
t1 := src.Dup()
t2 := canvas.NewCanvas(src.Width, src.Height)
for i := 0; i < n; i++ {
canvas.Say("WholeStep", i)
o.WholeStep(t1, t2)
t1, t2 = t2, t1
t2.Fill(0, 0, t2.Width, t2.Height, canvas.Black)
}
return t1
}
func (o IFS) WholeStep(src *canvas.Canvas, dest *canvas.Canvas) {
wait := make(chan int)
for k := 0; k < len(o.Choices); k++ {
canvas.Say(" go Map", k)
go o.Choices[k].MapImageTo(src, dest, k, wait)
}
for k := 0; k < len(o.Choices); k++ {
w := <-wait
canvas.Say(" Waited", w)
}
}
// MapImageTo maps one picture through an IFS onto another.
func (o Affine) MapImageTo(src *canvas.Canvas, dest *canvas.Canvas, k int, done chan int) {
for i := 0; i < src.Width; i++ {
x := float64(i) / src.FWidth
for j := 0; j < src.Height; j++ {
r, g, b := src.Get(i, j)
if r > 0 || g > 0 || b > 0 {
y := float64(j) / src.FHeight
x2, y2 := o.Apply(x, y)
dest.FSet(x2, y2, canvas.RGB(r, g, b))
}
}
}
done <- k
}
// Choose one member of the IFS.
func (o IFS) Choose() *Affine {
r := rand.Intn(len(o.Choices))
return o.Choices[r]
}
// CheckOne checks result of scanf of one item.
func CheckOne(n int, err error) {
if n != 1 || err != nil {
panic(Errorf("Bad Number: %s", err))
}
}
// ParseIfsParams parses list of matrices, or the name of a Builtin.
func ParseIfsParams(p string) *IFS {
z := make([]*Affine, 0)
if len(p) > 0 && unicode.IsLetter(rune(p[0])) {
p2, ok := Builtin[p]
if !ok {
panic(Errorf("Unknown Builtin: %q", p))
}
p = p2
}
pp := strings.Split(p, ",")
for _, f := range pp {
ff := strings.Split(f, " ")
if len(ff) != 6 {
panic(Errorf("bad IFS params: %q %q %q", p, f, ff))
}
aff := &Affine{}
if ff[0][0] == '@' {
var xa, ya, xb, yb, xc, yc float64
CheckOne(Sscanf(ff[0][1:], "%f", &xa))
CheckOne(Sscanf(ff[1], "%f", &ya))
CheckOne(Sscanf(ff[2], "%f", &xb))
CheckOne(Sscanf(ff[3], "%f", &yb))
CheckOne(Sscanf(ff[4], "%f", &xc))
CheckOne(Sscanf(ff[5], "%f", &yc))
aff.A = xb - xa
aff.C = yb - ya
aff.E = xc - aff.A
aff.F = yc - aff.C
aff.B = xa - aff.E
aff.D = ya - aff.F
} else {
CheckOne(Sscanf(ff[0], "%f", &aff.A))
CheckOne(Sscanf(ff[1], "%f", &aff.B))
CheckOne(Sscanf(ff[2], "%f", &aff.C))
CheckOne(Sscanf(ff[3], "%f", &aff.D))
CheckOne(Sscanf(ff[4], "%f", &aff.E))
CheckOne(Sscanf(ff[5], "%f", &aff.F))
}
z = append(z, aff)
}
return &IFS{Choices: z}
}