What causes ""No function name found in shader code"" in BabylonJS/Babylon.js?

Inspect the shader near the reported location and give the function a proper name: `void doWork() { ... }`.

BabylonJS/Babylon.js · error · Error

"No function name found in shader code"

Error message

"No function name found in shader code"

What it means

ExtractFunctions scans the shader with GetFunctionHeaderRegEx; a header match whose capture group 1 (the function name) is empty means the regex matched something that looks like a function header but has no identifier. The parser cannot register a nameless function, so it throws. This is rare — usually a symptom of unusual syntax near a function definition.

Source

Thrown at packages/dev/smartFilters/src/utils/buildTools/shaderConverter.ts:357

    mainFunctionName: string;
} {
    const extractedFunctions: ShaderFunction[] = [];
    let mainFunctionName: string | undefined;
    let pos = 0;

    const getFunctionHeaderRegEx = new RegExp(GetFunctionHeaderRegExString, GetFunctionHeaderRegExOptions);

    while (pos < fragment.length) {
        // Match the next available function header in the fragment code
        getFunctionHeaderRegEx.lastIndex = pos;
        const match = getFunctionHeaderRegEx.exec(fragment);
        if (!match) {
            break;
        }

        const functionName = match[1];
        if (!functionName) {
            throw new Error("No function name found in shader code");
        }

        const functionParams = match[2] || "";

        // Store start index of the function definition
        const startIndex = match.index;

        // Balance braces to find end of function, starting just after the opening `{`
        let endIndex = match.index + match[0].length;
        let depth = 1;
        while (depth > 0 && endIndex < fragment.length) {
            if (fragment[endIndex] === "{") {
                depth++;
            } else if (fragment[endIndex] === "}") {
                depth--;
            }
            endIndex++;
        }

View on GitHub (pinned to 0592b347b8)

Solutions

Inspect the shader near the reported location and give the function a proper name: `void doWork() { ... }`.
Resolve/expand any preprocessor macros that might hide the function name before conversion.
Simplify exotic syntax around function declarations (no attributes/annotations directly confusing the header pattern).

Example fix

// before
void () {
  gl_FragColor = vec4(1.0);
}
// after
void fillColor() {
  gl_FragColor = vec4(1.0);
}

Defensive patterns

Strategy: validation

Validate before calling

const headers = [...shader.matchAll(/\b\w+\s+(\w*)\s*\([^)]*\)\s*\{/g)];
if (headers.some(m => !m[1])) throw new Error("Shader contains a function header with an empty name");

Type guard

function allFunctionsNamed(shader: string): boolean {
  return [...shader.matchAll(/\b\w+\s+(\w*)\s*\([^)]*\)\s*\{/g)].every(m => m[1].length > 0);
}

Try / catch

try {
  const info = ParseFragmentShader(blockName, namespace, shader);
} catch (e) {
  if (e instanceof Error && e.message === "No function name found in shader code") {
    // locate the unnamed function near the reported position and name it
  } else throw e;
}

Prevention

Always name functions; never emit placeholder/anonymous headers from codegen.
Expand or remove macros around function declarations before conversion.
Run a GLSL syntax validator on shaders as a pre-build step.

When it happens

Trigger: ExtractFunctions (via ParseFragmentShader) on shader code where the function-header regex matches a construct with an empty name capture, e.g. malformed syntax like `void () { }`, macro-expanded code that erased the identifier, or regex edge cases with anonymous-looking constructs.

Common situations: Shaders generated by codegen/templates with broken placeholders (`void %s(...)` unresolved); heavy macro usage that confuses the header regex; typos like a missing function name after the return type.

Related errors

AI-assisted analysis of BabylonJS/Babylon.js@0592b347b8 (2026-08-30). Data as JSON: /api/errors/c1fc4f409fdde646. Report an issue: GitHub.