What causes ""Uniform line not found"" in BabylonJS/Babylon.js?

Ensure every uniform annotation is directly followed by a valid 'uniform ;' line.

BabylonJS/Babylon.js · error · Error

"Uniform line not found"

Error message

"Uniform line not found"

What it means

ParseFragmentShader matches uniform declarations with an annotation regex; group 1 is the optional JSON annotation and group 2 is the uniform declaration line. If the regex matched but the uniform line itself is empty, the annotation is malformed/unattached, so this error is thrown.

Source

Thrown at packages/dev/smartFilters/src/utils/buildTools/shaderConverter.ts:134

 * @param fragmentShader - The fragment shader to process
 * @returns The processed fragment shader
 */
export function ParseFragmentShader(fragmentShader: string): FragmentShaderInfo {
    const { header, fragmentShaderWithoutHeader } = ReadHeader(fragmentShader);
    fragmentShader = fragmentShaderWithoutHeader;
    const blockType = header?.[SmartFilterBlockTypeKey] || undefined;
    const namespace = header?.namespace || null;

    // Read the uniforms
    const uniforms: UniformMetadata[] = [];
    const uniformRegExp = new RegExp(/(\/\/\s*\{.*\}\s*(?:\r\n|\r|\n)+)?(uniform .*)/gm);
    const uniformGroups = fragmentShader.matchAll(uniformRegExp);
    for (const matches of uniformGroups) {
        const annotationJSON = matches[1];
        const uniformLine = matches[2];

        if (!uniformLine) {
            throw new Error("Uniform line not found");
        }

        const uniformLineMatches = new RegExp(/^uniform\s+(\w+)\s+(\w+)\s*;?/gm).exec(uniformLine);
        if (!uniformLineMatches || uniformLineMatches.length < 3) {
            throw new Error(`Uniforms must have a type and a name: '${uniformLine}'`);
        }
        const uniformTypeString = uniformLineMatches[1];
        const uniformName = uniformLineMatches[2];

        if (!uniformTypeString) {
            throw new Error(`Uniforms must have a type: '${uniformLine}'`);
        }
        if (!uniformName) {
            throw new Error(`Uniforms must have a name: '${uniformLine}'`);
        }

        // Convert to ConnectionPointType
        let type: ConnectionPointType;

View on GitHub (pinned to 0592b347b8)

Solutions

Ensure every uniform annotation is directly followed by a valid 'uniform <type> <name>;' line.
Remove orphaned annotation comments that no longer precede a uniform.
Check line endings/formatting so the uniform statement is on the line after the annotation.

Example fix

// before
/// {"autoBind": true}

// after
/// {"autoBind": true}
uniform float textureWidth;

Defensive patterns

Strategy: validation

Validate before calling

// Each '/// {...}' annotation must be immediately followed by a uniform line
const lines = fs.readFileSync(glslPath, 'utf8').split('\n');
lines.forEach((l, i) => { if (/^\s*\/\/\/\s*\{/.test(l) && !/^\s*uniform\b/.test(lines[i+1] ?? '')) console.error(`Orphan annotation at line ${i+1} of ${glslPath}`); });

Try / catch

try { await ConvertShader(path, ...); } catch (e) { if (e.message.includes('Uniform line not found')) { fixOrphanAnnotation(path); } else { throw e; } }

Prevention

Always pair annotation comments with the uniform on the next line.
Delete annotations when deleting their uniform.
Lint for orphan '///' JSON comments.

When it happens

Trigger: A uniform annotation comment (e.g. /// {"x":...}) immediately followed by an empty or missing 'uniform' declaration line, so the regex's second capture group is empty.

Common situations: Annotation comment left behind after the uniform line was deleted; comment formatting broke the uniform match; template generation emitted an annotation without the uniform.

Related errors

AI-assisted analysis of BabylonJS/Babylon.js@0592b347b8 (2026-08-30). Data as JSON: /api/errors/eb892582dd4989c0. Report an issue: GitHub.