Fix source maps in minified build files.

[ycw]

fix: #26779

The cause: if magicstring generates map without hires, many mappings in the map generated from terser plugin will be lost.

A solution is that, enables hires for those plugins came after terser()

// rollup.config.json

function header() {
  return { 
    renderChunk(code, id) {
      code = new MagicString(..
      return { map: code.generateMap({ hires: true }) .. // <<<

// builds
const builds = [ {
  input: 'src/Three.js',
  plugins: [
    ..,
    terser(),
    header(),
    ..
  ]

A workaround (this PR) simply re-orders the plugins: let terser plugin be the last one; (no hires, quicker)

// rollup.config.json

const builds = [ {
  input: 'src/Three.js',
  plugins: [
    ..,
    header(),
    ..,
    terser()  // <<< 
  ]

without PR:

with PR:

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

Filesize dev	Filesize PR	Diff
647.9 kB (160.9 kB)	647.9 kB (160.9 kB)	+0 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

Filesize dev	Filesize PR	Diff
441.3 kB (107 kB)	441.3 kB (107 kB)	+0 B

[Mugen87]

As long as the new order does not mess up the license I'm okay with this change. It seems this is the case when tested locally.

[ycw]

additonal detail: both the deprecationwarnings and @licence will be kept after applying terser (the last plugin). 👍🏻

e.g. for those who try self-host minified build with external sourcemaps support:

$ npx rollup -c utils/build/rollup.config.js -m

three.min.js:

three.module.min.js: