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Calling Unity scripts functions from JavaScript

December 17, 2022

I am attempting to call a unity script from JS but there is no MyGameInstance as seen in the Unity Documentation: https://docs.unity3d.com/Manual/webgl-interactingwithbrowserscripting.html

Here is a slightly modified (removed the footer) version of the html that WebGL produced by Unity’s Run and Build function:

<!DOCTYPE html>
<html lang="en-us">
  <head>
    <meta charset="utf-8">
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <title>Unity WebGL Player | communication</title>
    <link rel="shortcut icon" href="TemplateData/favicon.ico">
    <link rel="stylesheet" href="TemplateData/style.css">
  </head>
  <body>
    <div id="unity-container" class="unity-desktop">
      <canvas id="unity-canvas" width=960 height=600></canvas>
      <div id="unity-loading-bar">
        <div id="unity-logo"></div>
        <div id="unity-progress-bar-empty">
          <div id="unity-progress-bar-full"></div>
        </div>
      </div>
      <div id="unity-warning"> </div>
      <input type="checkbox">
    </div>
    <script>
      var container = document.querySelector("#unity-container");
      var canvas = document.querySelector("#unity-canvas");
      var loadingBar = document.querySelector("#unity-loading-bar");
      var progressBarFull = document.querySelector("#unity-progress-bar-full");
      var warningBanner = document.querySelector("#unity-warning");

      // Shows a temporary message banner/ribbon for a few seconds, or
      // a permanent error message on top of the canvas if type=='error'.
      // If type=='warning', a yellow highlight color is used.
      // Modify or remove this function to customize the visually presented
      // way that non-critical warnings and error messages are presented to the
      // user.
      function unityShowBanner(msg, type) {
        function updateBannerVisibility() {
          warningBanner.style.display = warningBanner.children.length ? 'block' : 'none';
        }
        var div = document.createElement('div');
        div.innerHTML = msg;
        warningBanner.appendChild(div);
        if (type == 'error') div.style = 'background: red; padding: 10px;';
        else {
          if (type == 'warning') div.style = 'background: yellow; padding: 10px;';
          setTimeout(function() {
            warningBanner.removeChild(div);
            updateBannerVisibility();
          }, 5000);
        }
        updateBannerVisibility();
      }

      var buildUrl = "Build";
      var loaderUrl = buildUrl + "/webgl.loader.js";
      var config = {
        dataUrl: buildUrl + "/webgl.data.br",
        frameworkUrl: buildUrl + "/webgl.framework.js.br",
        codeUrl: buildUrl + "/webgl.wasm.br",
        streamingAssetsUrl: "StreamingAssets",
        companyName: "DefaultCompany",
        productName: "communication",
        productVersion: "1.0",
        showBanner: unityShowBanner,
      };

      // By default Unity keeps WebGL canvas render target size matched with
      // the DOM size of the canvas element (scaled by window.devicePixelRatio)
      // Set this to false if you want to decouple this synchronization from
      // happening inside the engine, and you would instead like to size up
      // the canvas DOM size and WebGL render target sizes yourself.
      // config.matchWebGLToCanvasSize = false;

      if (/iPhone|iPad|iPod|Android/i.test(navigator.userAgent)) {
        container.className = "unity-mobile";
        // Avoid draining fillrate performance on mobile devices,
        // and default/override low DPI mode on mobile browsers.
        config.devicePixelRatio = 1;
        unityShowBanner('WebGL builds are not supported on mobile devices.');
      } else {
        canvas.style.width = "960px";
        canvas.style.height = "600px";
      }
      loadingBar.style.display = "block";

      var script = document.createElement("script");
      script.src = loaderUrl;
      script.onload = () => {
        createUnityInstance(canvas, config, (progress) => {
          progressBarFull.style.width = 100 * progress + "%";
        }).then((unityInstance) => {
          loadingBar.style.display = "none";
        }).catch((message) => {
          alert(message);
        });
      };

      document.body.appendChild(script);

    </script>
  </body>
</html>

I am trying to call the control function in the following script:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class onoff : MonoBehaviour
{
    public GameObject square;

    public void ctrl(string text) {
        if (text == "0") {
            square.SetActive(false);
        }
        if (text == "1") {
            square.SetActive(true);
        }
    }
}

This is the format of the SendMessage comamnd I have been attempting to do: MyGameInstance.SendMessage('Main Camera', 'ctrl', '0');

>Solution :

In the createUnityInstance.then method, under loadingBar.style.display = "none";, you should be able to put the SendMessage call. Be sure to replace MyGameInstance with unityInstance.

createUnityInstance(canvas, config, (progress) => {
  progressBarFull.style.width = 100 * progress + "%";
}).then((unityInstance) => {
  loadingBar.style.display = "none";
  unityInstance.SendMessage('Main Camera', 'ctrl', '0');
})

To continue using unityInstance throughout your code, there are two methods.

Use const instance = await createUnityInstance(...); and make the outer function async
Set instance in .then

Here is the code for the first option:

script.onload = async () => {
 const intance = createUnityInstance(canvas, config, (progress) => {
   progressBarFull.style.width = 100 * progress + "%";
 }).then((unityInstance) => {
   loadingBar.style.display = "none";
 }).catch((message) => {
   alert(message);
 });

 instance.SendMessage('Main Camera', 'ctrl', '0');
};

Code for the second option:

.then((unityInstance) => {
  instance = unityInstance;
})

Note that instance is defined outside .then.

unity-webgl

byMR

Published December 17, 2022

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