WebGL/WebGL2: any integer-valued number ≥ 1e21 emits invalid GLSL (1e+30.0) #864

Summary

On the WebGL and WebGL2 backends, an integer-valued number of 1e21 or larger produces a fragment shader that fails to compile:

Error compiling fragment shader: ERROR: 0:518: '.0' : syntax error

The generated GLSL contains 1e+30.0, which is not a valid float literal.

1e30 is a natural thing to write — it is the usual "infinitely far away" sentinel in a ray marcher or path tracer, which is where I hit it.

Reproduction

Verified on gpu.js 2.21.0, Chrome 150, Apple M1 Max (apple metal-3), via dist/gpu-browser.js.

// FAILS — literal in the kernel body
new GPU({ mode: 'webgl2' })
  .createKernel(function () { return 1e30; })
  .setOutput([1])();

// FAILS — value passed through setConstants
new GPU({ mode: 'webgl2' })
  .createKernel(function () { return this.constants.big * 1; })
  .setConstants({ big: 1e30 })
  .setOutput([1])();

// OK — runtime argument, uploaded as a uniform rather than emitted into source
new GPU({ mode: 'webgl2' })
  .createKernel(function (v) { return v * 1; })
  .setOutput([1])(1e30);

Affected backends

Cause

The threshold is exactly 1e21, which is where Number.prototype.toString() switches to exponential notation:

(1e20).toString()  // "100000000000000000000"  -> "100000000000000000000.0"  valid
(1e21).toString()  // "1e+21"                  -> "1e+21.0"                  invalid

src/backend/web-gl/function-node.js (around line 237) appends .0 whenever the value is an integer:

if (Number.isInteger(ast.value)) {
  ...
  retArr.push(`${ast.value}.0`);

Number.isInteger(1e30) is true, so the .0 is appended to a string that is already in exponential form.

Suggested fix

Only append .0 when the rendered string does not already make the literal a float. GLSL accepts 1e30 as a float literal, so the exponential form can pass through unchanged:

const s = `${ast.value}`;
retArr.push(/[.eE]/.test(s) ? s : `${s}.0`);

The same ${value}.0 pattern appears in src/backend/function-node.js and src/backend/web-gpu/function-node.js; I only observed the failure on the two WebGL backends, so I have not checked whether the others are reachable with the same input.

Workaround

Keep sentinels below 1e21 — 1e20 renders as digits and works, and for most scenes something like 1e9 is plenty.