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ebiten.CursorPosition() does not always return (0,0) on mobile, when the game is compiled to WASM and runs in browser. #3087

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Duxo opened this issue Sep 8, 2024 · 5 comments
Closed
2 of 11 tasks

ebiten.CursorPosition() does not always return (0,0) on mobile, when the game is compiled to WASM and runs in browser. #3087

Duxo opened this issue Sep 8, 2024 · 5 comments
Labels
bug documentation os:android os:js
Milestone
v2.8.0

Comments

@Duxo
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Duxo commented Sep 8, 2024

Ebitengine Version

v2.7.8

Operating System

  • Windows
  • macOS
  • Linux
  • FreeBSD
  • OpenBSD
  • Android
  • iOS
  • Nintendo Switch
  • PlayStation 5
  • Xbox
  • Web Browsers

Go Version (go version)

1.23.1

What steps will reproduce the problem?

Game: (built with env GOOS=js GOARCH=wasm go build -o test.wasm)

package main

import (
	"fmt"
	"log"

	"github.com/hajimehoshi/ebiten/v2"
)

type Game struct{}

func (g *Game) Layout(w int, h int) (int, int) {
	return w, h
}

func (g *Game) Update() error {
	fmt.Println(ebiten.CursorPosition())
	return nil
}

func (g *Game) Draw(screen *ebiten.Image) {}

func main() {
	err := ebiten.RunGame(&Game{})
	if err != nil {
		log.Fatal(err)
	}
}

HTML:

<!DOCTYPE html>

<html>

<head>
    <style>
        #mobile-input {
            position: absolute;
            height: 100%;
            width: 100%;
        }
    </style>
</head>

<body>
    <div id="mobile-input"></div>
    <script src="wasm/wasm_exec.js"></script>
    <script>
        const mobileInput = document.getElementById('mobile-input')
        const go = new Go();
        WebAssembly.instantiateStreaming(fetch("wasm/test.wasm"), go.importObject).then(result => {
            go.run(result.instance)
            mobileInput.addEventListener('touchstart', (event) => { mobileInput.style.zIndex = '-1' })
        })
    </script>
</body>

</html>

What is the expected result?

I expected that ebiten.CursorPosition() will always return (0,0) on mobile.

What happens instead?

After the mobile screen is touched, the ebiten.CursorPosition() returns the coordinates of the touch.

Anything else you feel useful to add?

The problem is present in Firefox and Chrome.
@Duxo Duxo added the bug label Sep 8, 2024
@hajimehoshi
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hajimehoshi commented Sep 8, 2024 •
edited
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CursorPosition can return a mouse cursor position if you use a mouse for Android. There is no assumption that CursorPosition returns (0, 0) by default.

@hajimehoshi
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For touches, use the APIs for touches. https://pkg.go.dev/github.com/hajimehoshi/ebiten/v2#TouchID

@hajimehoshi hajimehoshi closed this as not planned Won't fix, can't repro, duplicate, stale Sep 8, 2024
@hajimehoshi hajimehoshi added wontfix and removed bug labels Sep 8, 2024
@Duxo
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Duxo commented Sep 9, 2024

The problem is that the CursorPosition() returned a different value than (0,0) on Android without the mouse. Also, the documentation says: "CursorPosition always returns (0, 0) on mobiles."

Sorry for sounding assertive; it is the most compact way I managed to write it.

@hajimehoshi hajimehoshi reopened this Sep 9, 2024
@hajimehoshi hajimehoshi added bug and removed wontfix labels Sep 9, 2024
@hajimehoshi
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hajimehoshi commented Sep 9, 2024 •
edited
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Ah, yes, that seems an issue.

Also I was misunderstanding that Ebitengine detected a mouse for Android apps but was actually not (yet). I'm sorry, I'll take a look.

@hajimehoshi
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The confusing point is

  • CursorPosition should return (0, 0) on Android apps.
  • CursorPosition should return a mouse cursor position on Android browsers.

I'll update the comment.

@hajimehoshi hajimehoshi added this to the v2.8.0 milestone Sep 9, 2024
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@hajimehoshi @Duxo