getting a webgl context fails on macOS

[hajimehoshi]

1. Create this test (main_test.go)

package main_test

import (
	"syscall/js"
	"testing"
)

func TestWebGL(t *testing.T) {
	window := js.Global().Get("window")
	document := window.Get("document")
	body := document.Get("body")
	canvas := document.Call("createElement", "canvas")
	body.Call("appendChild", canvas)
	if context := canvas.Call("getContext", "2d"); !context.Truthy() {
		t.Fatal("getContext('2d') failed")
	}
	if context := canvas.Call("getContext", "webgl"); !context.Truthy() {
		t.Fatal("getContext('webgl') failed")
	}
}

2. Run the test

GOOS=js GOARCH=wasm go test . 

The test fails:

--- FAIL: TestWebGL (0.01s)
    main_test.go:18: getContext('webgl') failed
FAIL
exit with status 1
FAIL    github.com/hajimehoshi/ebiten/v2/examples/test  0.755s
FAIL

The test fails even with WASM_HEADLESS=off.

My environment is:

                    'c.          [email protected] 
                 ,xNMM.          ------------------------------------- 
               .OMMMMo           OS: macOS 14.4 23E214 arm64 
               OMMM0,            Host: Mac15,6 
     .;loddo:' loolloddol;.      Kernel: 23.4.0 
   cKMMMMMMMMMMNWMMMMMMMMMM0:    Uptime: 42 days, 10 hours, 10 mins 
 .KMMMMMMMMMMMMMMMMMMMMMMMWd.    Packages: 135 (brew) 
 XMMMMMMMMMMMMMMMMMMMMMMMX.      Shell: zsh 5.9 
;MMMMMMMMMMMMMMMMMMMMMMMM:       Resolution: 1800x1169 
:MMMMMMMMMMMMMMMMMMMMMMMM:       DE: Aqua 
.MMMMMMMMMMMMMMMMMMMMMMMMX.      WM: Quartz Compositor 
 kMMMMMMMMMMMMMMMMMMMMMMMMWd.    WM Theme: Blue (Light) 
 .XMMMMMMMMMMMMMMMMMMMMMMMMMMk   Terminal: vscode 
  .XMMMMMMMMMMMMMMMMMMMMMMMMK.   CPU: Apple M3 Pro 
    kMMMMMMMMMMMMMMMMMMMMMMd     GPU: Apple M3 Pro 
     ;KMMMMMMMWXXWMMMMMMMk.      Memory: 3640MiB / 18432MiB 
       .cooc,.    .,coo:.

My wasmbrowsertest version is 6e494bb.

[agnivade]

Hmm.. I don't have a mac. But I will see if I can find something.

[agnivade]

@hajimehoshi - does it work if you manually paste the commands in a browser console? I just tried the following and got null for webgl

> let cc = document.createElement("canvas")
< undefined
> cc.getContext("2d")
< CanvasRenderingContext2D {canvas: canvas, globalAlpha: 1, globalCompositeOperation: 'source-over', filter: 'none', imageSmoothingEnabled: true, …}
> cc.getContext("webgl")
< null

[hajimehoshi]

The result was the same on the console.

EDIT: skipping to get 2d canvas changed the result:

[hajimehoshi]

Hm, apparently this is the same on Windows

> cat .\examples\test\main_test.go
package main_test

import (
        "syscall/js"
        "testing"
)

func TestWebGL(t *testing.T) {
        window := js.Global().Get("window")
        document := window.Get("document")
        body := document.Get("body")
        canvas := document.Call("createElement", "canvas")
        body.Call("appendChild", canvas)
        if context := canvas.Call("getContext", "webgl"); !context.Truthy() {
                t.Fatal("getContext('webgl') failed")
        }
}

> & (Get-Process -Id $PID).Path { $env:GOOS="js"; $env:GOARCh="wasm"; go test -exec="\\Mac\Home\ebiten\wasmbrowsertest.exe" .\examples\test\ }
--- FAIL: TestWebGL (0.00s)
    main_test.go:18: getContext('webgl') failed
FAIL
exit with status 1
FAIL    github.com/hajimehoshi/ebiten/v2/examples/test  1.130s
FAIL

[agnivade]

Ok, so it's a chromedp thing: chromedp/chromedp#1190. I'll take a deeper look.

[agnivade]

@hajimehoshi - Could you try with this branch: https://github.com/agnivade/wasmbrowsertest/tree/webgl and see if this helps? Unfortunately, my laptop doesn't support webgl so it's a bit difficult for me.

[hajimehoshi]

Hmm, this never returns...

hajimehoshi@Hajimes-MacBook-Pro wasmtest % cat main_test.go 
package main_test

import (
        "syscall/js"
        "testing"
)

func TestWebGL(t *testing.T) {
        window := js.Global().Get("window")
        document := window.Get("document")
        body := document.Get("body")
        canvas := document.Call("createElement", "canvas")
        body.Call("appendChild", canvas)
        if context := canvas.Call("getContext", "2d"); !context.Truthy() {
                t.Fatal("getContext('2d') failed")
        }
        if context := canvas.Call("getContext", "webgl"); !context.Truthy() {
                t.Fatal("getContext('webgl') failed")
        }
}
hajimehoshi@Hajimes-MacBook-Pro wasmtest % GOOS=js GOARCH=wasm go test .

[agnivade]

Ugh .. sorry about that. I have a strong suspicion that it's got to do with some flag that is disabled by default in the headless Chrome, but works in the normal browser instance. But since I don't have a box to repro this, it is difficult for me.

I think this issue isn't even related to wasmbrowsertest. You might be able to get a standalone repro with just using chromedp, by running a piece of JS. If we can get to that, then it becomes easier to work on it. And even possibly report to chromedp team.