@luma.gl/shadertools/dist/esm/lib/transpile-shader.js

Shader module system for luma.gl

function testVariable(qualifier) {
  return new RegExp("\\b".concat(qualifier, "[ \\t]+(\\w+[ \\t]+\\w+(\\[\\w+\\])?;)"), 'g');
}

const ES300_REPLACEMENTS = [[/^(#version[ \t]+(100|300[ \t]+es))?[ \t]*\n/, '#version 300 es\n'], [/\btexture(2D|2DProj|Cube)Lod(EXT)?\(/g, 'textureLod('], [/\btexture(2D|2DProj|Cube)(EXT)?\(/g, 'texture(']];
const ES300_VERTEX_REPLACEMENTS = [...ES300_REPLACEMENTS, [testVariable('attribute'), 'in $1'], [testVariable('varying'), 'out $1']];
const ES300_FRAGMENT_REPLACEMENTS = [...ES300_REPLACEMENTS, [testVariable('varying'), 'in $1']];
const ES100_REPLACEMENTS = [[/^#version[ \t]+300[ \t]+es/, '#version 100'], [/\btexture(2D|2DProj|Cube)Lod\(/g, 'texture$1LodEXT('], [/\btexture\(/g, 'texture2D('], [/\btextureLod\(/g, 'texture2DLodEXT(']];
const ES100_VERTEX_REPLACEMENTS = [...ES100_REPLACEMENTS, [testVariable('in'), 'attribute $1'], [testVariable('out'), 'varying $1']];
const ES100_FRAGMENT_REPLACEMENTS = [...ES100_REPLACEMENTS, [testVariable('in'), 'varying $1']];
const ES100_FRAGMENT_OUTPUT_NAME = 'gl_FragColor';
const ES300_FRAGMENT_OUTPUT_REGEX = /\bout[ \t]+vec4[ \t]+(\w+)[ \t]*;\n?/;
const REGEX_START_OF_MAIN = /void\s+main\s*\([^)]*\)\s*\{\n?/;
export default function transpileShader(source, targetGLSLVersion, isVertex) {
  switch (targetGLSLVersion) {
    case 300:
      return isVertex ? convertShader(source, ES300_VERTEX_REPLACEMENTS) : convertFragmentShaderTo300(source);

    case 100:
      return isVertex ? convertShader(source, ES100_VERTEX_REPLACEMENTS) : convertFragmentShaderTo100(source);

    default:
      throw new Error("unknown GLSL version ".concat(targetGLSLVersion));
  }
}

function convertShader(source, replacements) {
  for (const [pattern, replacement] of replacements) {
    source = source.replace(pattern, replacement);
  }

  return source;
}

function convertFragmentShaderTo300(source) {
  source = convertShader(source, ES300_FRAGMENT_REPLACEMENTS);
  const outputMatch = source.match(ES300_FRAGMENT_OUTPUT_REGEX);

  if (outputMatch) {
    const outputName = outputMatch[1];
    source = source.replace(new RegExp("\\b".concat(ES100_FRAGMENT_OUTPUT_NAME, "\\b"), 'g'), outputName);
  } else {
    const outputName = 'fragmentColor';
    source = source.replace(REGEX_START_OF_MAIN, match => "out vec4 ".concat(outputName, ";\n").concat(match)).replace(new RegExp("\\b".concat(ES100_FRAGMENT_OUTPUT_NAME, "\\b"), 'g'), outputName);
  }

  return source;
}

function convertFragmentShaderTo100(source) {
  source = convertShader(source, ES100_FRAGMENT_REPLACEMENTS);
  const outputMatch = source.match(ES300_FRAGMENT_OUTPUT_REGEX);

  if (outputMatch) {
    const outputName = outputMatch[1];
    source = source.replace(ES300_FRAGMENT_OUTPUT_REGEX, '').replace(new RegExp("\\b".concat(outputName, "\\b"), 'g'), ES100_FRAGMENT_OUTPUT_NAME);
  }

  return source;
}
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