Added implementation for a wasm backend

[MeKo-Christian]

No description provided.

[gonutz]

Very nice, I just took it for a little test drive.
Already, the original semantics make less sense in the browser context. As always, I said

if window.WasKeyPressed(draw.KeyEscape) {
	window.Close()
}

which in your current implementation will stop accepting input but keep drawing the same state.

What do you think about this instead:

func (w *wasmWindow) Close() {
	js.Global().Get("window").Get("location").Call("reload")
}

which would reload the page on Close? I am not sure what makes the most sense, since we do not want to close the browser tab :-)

[gonutz]

Another thing: how do I play a sound file? I just tried

if window.WasKeyPressed(draw.KeySpace) {
	window.PlaySoundFile("prototype-demo.wav")
}

using your catchy demo tune but this crashes the program with this log:

wasm_exec.js:22 fatal error: all goroutines are asleep - deadlock!
wasm_exec.js:22 
wasm_exec.js:22 goroutine 1 [select (no cases)]:
wasm_exec.js:22 github.com/gonutz/prototype/draw.RunWindow({0x28c8d, 0x5}, 0x320, 0x258, 0x140a030)
wasm_exec.js:22 	C:/code/meko/prototype/draw/window_wasm.go:162 +0x3b
wasm_exec.js:22 main.main()
wasm_exec.js:22 	C:/code/meko/testdrive/main.go:7 +0x7
wasm_exec.js:22 
wasm_exec.js:22 goroutine 6 [chan receive]:
wasm_exec.js:22 github.com/gonutz/prototype/draw.(*wasmWindow).loadSoundFile(0x144c000, {0x2af58, 0x12})
wasm_exec.js:22 	C:/code/meko/prototype/draw/window_wasm.go:239 +0xf
wasm_exec.js:22 github.com/gonutz/prototype/draw.(*wasmWindow).PlaySoundFile(0x144c000, {0x2af58, 0x12})
wasm_exec.js:22 	C:/code/meko/prototype/draw/window_wasm.go:674 +0x2
wasm_exec.js:22 main.main.func1({0x4a248, 0x144c000})
wasm_exec.js:22 	C:/code/meko/testdrive/main.go:13 +0xa
wasm_exec.js:22 github.com/gonutz/prototype/draw.RunWindow.func9({{}, 0x0, 0x0}, {0x140f2d0, 0x1, 0x1})
wasm_exec.js:22 	C:/code/meko/prototype/draw/window_wasm.go:145 +0x7
wasm_exec.js:22 syscall/js.handleEvent()
wasm_exec.js:22 	C:/bin/go/src/syscall/js/func.go:100 +0x23
wasm_exec.js:101 exit code: 2
globalThis.Go.constructor.exit @ wasm_exec.js:101
runtime.wasmExit @ wasm_exec.js:232
$func795 @ main.wasm:0xc22a9
...

where line 239 in windows_wasm.go is this one:

func (w *wasmWindow) loadSoundFile(path string) (js.Value, error) {
	if buffer, ok := w.audioBuffers[path]; ok {
...
		}))
		return nil
	})

	fetchPromise.Call("then", then)
***	<-done // <- panics here   ***

	return result, err
}

[MeKo-Christian]

if window.WasKeyPressed(draw.KeyEscape) {
	window.Close()
}

which in your current implementation will stop accepting input but keep drawing the same state.

As you mentioned, a close does actually not make much sense in the browser context, so maybe one could leave this just empty and it would be fine.

What do you think about this instead:

func (w *wasmWindow) Close() {
	js.Global().Get("window").Get("location").Call("reload")
}

which would reload the page on Close? I am not sure what makes the most sense, since we do not want to close the browser tab :-)

At least something. If you want, I can fix this in my PR. Then you can keep things clear, but it's up to you.

[MeKo-Christian]

Another thing: how do I play a sound file? I just tried

if window.WasKeyPressed(draw.KeySpace) {
	window.PlaySoundFile("prototype-demo.wav")
}

using your catchy demo tune but this crashes the program with this log:

wasm_exec.js:22 fatal error: all goroutines are asleep - deadlock!
wasm_exec.js:22 
wasm_exec.js:22 goroutine 1 [select (no cases)]:
wasm_exec.js:22 github.com/gonutz/prototype/draw.RunWindow({0x28c8d, 0x5}, 0x320, 0x258, 0x140a030)
wasm_exec.js:22 	C:/code/meko/prototype/draw/window_wasm.go:162 +0x3b
wasm_exec.js:22 main.main()
wasm_exec.js:22 	C:/code/meko/testdrive/main.go:7 +0x7
wasm_exec.js:22 
wasm_exec.js:22 goroutine 6 [chan receive]:
wasm_exec.js:22 github.com/gonutz/prototype/draw.(*wasmWindow).loadSoundFile(0x144c000, {0x2af58, 0x12})
wasm_exec.js:22 	C:/code/meko/prototype/draw/window_wasm.go:239 +0xf
wasm_exec.js:22 github.com/gonutz/prototype/draw.(*wasmWindow).PlaySoundFile(0x144c000, {0x2af58, 0x12})
wasm_exec.js:22 	C:/code/meko/prototype/draw/window_wasm.go:674 +0x2
wasm_exec.js:22 main.main.func1({0x4a248, 0x144c000})
wasm_exec.js:22 	C:/code/meko/testdrive/main.go:13 +0xa
wasm_exec.js:22 github.com/gonutz/prototype/draw.RunWindow.func9({{}, 0x0, 0x0}, {0x140f2d0, 0x1, 0x1})
wasm_exec.js:22 	C:/code/meko/prototype/draw/window_wasm.go:145 +0x7
wasm_exec.js:22 syscall/js.handleEvent()
wasm_exec.js:22 	C:/bin/go/src/syscall/js/func.go:100 +0x23
wasm_exec.js:101 exit code: 2
globalThis.Go.constructor.exit @ wasm_exec.js:101
runtime.wasmExit @ wasm_exec.js:232
$func795 @ main.wasm:0xc22a9
...

where line 239 in windows_wasm.go is this one:

func (w *wasmWindow) loadSoundFile(path string) (js.Value, error) {
	if buffer, ok := w.audioBuffers[path]; ok {
...
		}))
		return nil
	})

	fetchPromise.Call("then", then)
***	<-done // <- panics here   ***

	return result, err
}

This was on my todo list as well. Actually, that's why I initially wrote the demo in the first place. The audio code was written rather blindly and everything is more or less untested. Either you fix it on your own or I can have a look at it on the weekend.