#Custom SC2 Engine

ModLoader requires a modified SugarCube2 engine to bootstrap correctly. This page describes the engine changes and how to replace the engine without recompiling the game.

#Engine Repository

Modified SC2 engine: sugarcube-2_Vrelnir

Games that use this ModLoader must use this SC2 build.

#Engine Changes

#1. Startup Modification

The jQuery closure in sugarcube.js is modified to add ModLoader’s async wait and wrap the original startup in mainStart():

jQuery(() => {
  "use strict";

  const mainStart = () => {
    // Original contents of jQuery(() => {})
  };

  if (typeof window.modSC2DataManager !== "undefined") {
    window.modSC2DataManager
      .startInit()
      .then(() => window.jsPreloader.startLoad())
      .then(() => mainStart())
      .catch((err) => {
        console.error(err);
      });
  } else {
    mainStart();
  }
});

Startup changes from jQuery -> SC2 to jQuery -> ModLoader -> SC2.

#2. Wikifier Changes

_lastPassageQ and related data are added to track compilation. Relevant files:

• macrolib.js
• parserlib.js
• wikifier.js

Search for passageObj to locate changes.

#3. img/svg Tag Interception

Image creation (img and svg) is intercepted so all images can be loaded from memory (no server).

In Wikifier.Parser.add 'htmlTag':

if (
  typeof window.modSC2DataManager !== "undefined" &&
  typeof window.modSC2DataManager.getHtmlTagSrcHook?.()?.doHook !== "undefined"
) {
  if (tagName === "img" && !el.getAttribute("src")?.startsWith("data:")) {
    el.setAttribute("ML-src", el.getAttribute("src"));
    el.removeAttribute("src");
    window.modSC2DataManager
      .getHtmlTagSrcHook()
      .doHook(el)
      .catch((E) => console.error(E));
  }
}

#Replacing the Engine Without Recompiling

Use sc2ReplaceTool to swap in a new SC2 engine in compiled game HTML.

#Steps

1. Run the replacement:

node "<path to sc2ReplaceTool.js>" "<compiled game HTML>" "<path to format.js>"

Example:

node "dist-insertTools/sc2ReplaceTool.js" "Degrees of Lewdity VERSION.html" "build/twine2/sugarcube-2/format.js"

Output has .sc2replace.html suffix:

Degrees of Lewdity VERSION.html.sc2replace.html

2. Inject ModLoader into the result with insert2html:

node "dist-insertTools/insert2html.js" "Degrees of Lewdity VERSION.html.sc2replace.html" "modList.json" "dist-BeforeSC2/BeforeSC2.js"

Final output:

Degrees of Lewdity VERSION.html.sc2replace.html.mod.html

#Building the SC2 Engine

In the modified SC2 project:

node build.js -d -u -b 2

Output: build/twine2/sugarcube-2/format.js.