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2020-coding-projects/mandelbrot-webassembly/server/main.go

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2020-04-27 07:53:21 +00:00
package main
import (
"fmt"
"math"
"syscall/js"
)
type selection struct {
startX int
startY int
endX int
endY int
}
type mbRender struct {
doc js.Value
ctx js.Value
backCtx []js.Value
curCtx int
width float64
height float64
minX float64
minY float64
maxX float64
maxY float64
colorMode string
imageData js.Value
mandelbrot chan Mandelbrot
mandelbrotValue Mandelbrot
mandelbrotProgress chan float64
mandelbrotProgressValue float64
mouseDown bool
hasSelection bool
selection selection
}
type Mandelbrot []byte
func (mb *mbRender) getMandelbrot(maxIterations uint) {
go func() {
mb.mandelbrot <- mb.CalculateMandelbrot(maxIterations)
}()
}
func (mb *mbRender) start() {
mb.doc = js.Global().Get("document")
canvasEl := mb.doc.Call("getElementById", "canvas")
//mb.width = mb.doc.Get("body").Get("clientWidth").Float()
//mb.height = mb.doc.Get("body").Get("clientHeight").Float()
mb.width = 1000.0
mb.height = 1000.0
mb.minX = -2.0
mb.minY = -2.0
mb.maxX = 2
mb.maxY = 2
canvasEl.Set("width", mb.width)
canvasEl.Set("height", mb.height)
mb.ctx = canvasEl.Call("getContext", "2d")
mb.imageData = mb.ctx.Call("getImageData", 0, 0, mb.width, mb.height)
mb.mandelbrot = make(chan Mandelbrot)
mb.getMandelbrot(1000)
mouseDownEvt := js.FuncOf(func(this js.Value, args []js.Value) interface{} {
evt := args[0]
mb.mouseDown = true
mb.hasSelection = true
mb.selection = selection{
startX: evt.Get("clientX").Int() - canvasEl.Get("offsetLeft").Int(),
startY: evt.Get("clientY").Int() - canvasEl.Get("offsetTop").Int(),
endX: evt.Get("clientX").Int() - canvasEl.Get("offsetLeft").Int(),
endY: evt.Get("clientY").Int() - canvasEl.Get("offsetTop").Int(),
}
return nil
})
defer mouseDownEvt.Release()
mouseMoveEvt := js.FuncOf(func(this js.Value, args []js.Value) interface{} {
evt := args[0]
if mb.mouseDown {
posX := evt.Get("clientX").Int() - canvasEl.Get("offsetLeft").Int()
posY := evt.Get("clientY").Int() - canvasEl.Get("offsetTop").Int()
dx := posX - mb.selection.startX
dy := posY - mb.selection.startY
if math.Abs(float64(dx)) > math.Abs(float64(dy)) {
mb.selection.endX = mb.selection.startX + dx
mb.selection.endY = mb.selection.startY + dx
} else {
mb.selection.endX = mb.selection.startX + dy
mb.selection.endY = mb.selection.startY + dy
}
}
return nil
})
defer mouseMoveEvt.Release()
mouseUpEvt := js.FuncOf(func(this js.Value, args []js.Value) interface{} {
mb.mouseDown = false
mb.hasSelection = false
newMinX := CalcReal(float64(mb.selection.startX), mb.width, mb.minX, mb.maxX)
newMinY := CalcReal(float64(mb.selection.startY), mb.height, mb.minY, mb.maxY)
newMaxX := CalcReal(float64(mb.selection.endX), mb.width, mb.minX, mb.maxX)
newMaxY := CalcReal(float64(mb.selection.endY), mb.height, mb.minY, mb.maxY)
mb.minX = newMinX
mb.minY = newMinY
mb.maxX = newMaxX
mb.maxY = newMaxY
mb.getMandelbrot(uint(math.Min(1000*1/math.Sqrt((mb.maxX-mb.minX)), 100000)))
return nil
})
defer mouseUpEvt.Release()
canvasEl.Call("addEventListener", "mousedown", mouseDownEvt)
canvasEl.Call("addEventListener", "mousemove", mouseMoveEvt)
canvasEl.Call("addEventListener", "mouseup", mouseUpEvt)
var renderFrame js.Func
renderFrame = js.FuncOf(func(this js.Value, args []js.Value) interface{} {
// mb.ctx.Call("clearRect", 0, 0, mb.width, mb.height)
select {
case x, ok := <-mb.mandelbrot:
if ok {
mb.mandelbrotValue = x
}
default:
}
select {
case x, ok := <-mb.mandelbrotProgress:
if ok {
mb.mandelbrotProgressValue = x
}
default:
}
value := js.Global().Get("Uint8Array").New(len(mb.mandelbrotValue))
js.CopyBytesToJS(value, mb.mandelbrotValue)
mb.imageData.Get("data").Call("set", value)
mb.ctx.Call("putImageData", mb.imageData, 0, 0)
if mb.hasSelection {
mb.ctx.Set("fillStyle", "rgba(0, 0, 255, 0.8)")
mb.ctx.Call("fillRect", mb.selection.startX, mb.selection.startY, mb.selection.endX-mb.selection.startX, mb.selection.endY-mb.selection.startY)
}
js.Global().Call("requestAnimationFrame", renderFrame)
return nil
})
done := make(chan struct{}, 0)
js.Global().Call("requestAnimationFrame", renderFrame)
<-done
}
func (m Mandelbrot) SetPixel(width int, x int, y int, color []byte) {
start := y*int(width)*4 + x*4
for i := 0; i < 4; i++ {
m[start+i] = color[i]
}
}
func (mb mbRender) GetColor(iteration uint, maxIterations uint) []byte {
intensity := (math.Pi / 2.0) * float64(iteration) / float64(maxIterations)
return []byte{
byte(math.Sin(intensity) * 256),
byte(math.Sin(intensity*2) * 256),
byte(math.Cos(intensity) * 256),
255,
}
// HSL - red
/*c := colorful.Hsl(float64(iteration)/256, 1.0, float64(iteration)/(float64(iteration)+8.0))
return []byte{
byte(c.R * 255),
byte(c.G * 255),
byte(c.B * 255),
255,
}*/
}
func CalcReal(x, width, minX, maxX float64) float64 {
return (x*(maxX-minX))/width + minX
}
func CalcImaginary(y, height, minY, maxY float64) float64 {
return (y*(maxY-minY))/height + minY
}
func (mb *mbRender) CalculateMandelbrot(maxIterations uint) Mandelbrot {
fmt.Println("max iterations", maxIterations)
mandelbrot := make(Mandelbrot, int(mb.width*mb.height*4))
mb.mandelbrotProgress = make(chan float64)
for row := 0; row < int(mb.height); row++ {
for col := 0; col < int(mb.width); col++ {
cRe := CalcReal(float64(col), mb.width, mb.minX, mb.maxX)
cIm := CalcImaginary(float64(row), mb.height, mb.minY, mb.maxY)
var x float64
var y float64
var iteration uint
for ; x*x+y*y <= 4 && iteration < maxIterations; iteration++ {
newX := x*x - y*y + cRe
y = 2*x*y + cIm
x = newX
}
mandelbrot.SetPixel(int(mb.width), col, row, mb.GetColor(iteration, maxIterations))
}
go func() {
mb.mandelbrotProgress <- float64(row) / mb.height
}()
}
return mandelbrot
}
func main() {
fmt.Println("Hallo fögel")
mb := mbRender{}
mb.start()
}