Add existing to tracked

node_modules/@cesium/engine/Source/Renderer/demodernizeShader.js

@@ -0,0 +1,84 @@
+/**
+ * Transpiles a [GLSL 3.00]{@link https://registry.khronos.org/OpenGL/specs/es/3.0/GLSL_ES_Specification_3.00.pdf}
+ * shader to a [GLSL 1.00]{@link https://registry.khronos.org/OpenGL/specs/es/2.0/GLSL_ES_Specification_1.00.pdf} shader.
+ *
+ * This function does not aim to provide a comprehensive transpilation from GLSL 3.00 to GLSL 1.00; only the functionality
+ * used within the CesiumJS shaders is supported.
+ *
+ * @private
+ *
+ * @param {string} input The GLSL 3.00 shader.
+ * @param {boolean} isFragmentShader True if the shader is a fragment shader.
+ *
+ * @return {string}
+ */
+function demodernizeShader(input, isFragmentShader) {
+  let output = input;
+
+  // Remove version string got GLSL 3.00.
+  output = output.replaceAll(`version 300 es`, ``);
+
+  // Replace all texture calls with texture2D
+  output = output.replaceAll(
+    /(texture\()/g,
+    `texture2D(`, // Trailing ')' is included in the match group.
+  );
+
+  if (isFragmentShader) {
+    // Replace the in with varying.
+    output = output.replaceAll(
+      /\n\s*(in)\s+(vec\d|mat\d|float)/g,
+      `\nvarying $2`,
+    );
+
+    if (/out_FragData_(\d+)/.test(output)) {
+      output = `#extension GL_EXT_draw_buffers : enable\n${output}`;
+
+      // Remove all layout declarations for out_FragData.
+      output = output.replaceAll(
+        /layout\s+\(location\s*=\s*\d+\)\s*out\s+vec4\s+out_FragData_\d+;/g,
+        ``,
+      );
+
+      // Replace out_FragData with gl_FragData.
+      output = output.replaceAll(/out_FragData_(\d+)/g, `gl_FragData[$1]`);
+    }
+
+    // Remove all layout declarations for out_FragColor.
+    output = output.replaceAll(
+      /layout\s+\(location\s*=\s*0\)\s*out\s+vec4\s+out_FragColor;/g,
+      ``,
+    );
+
+    // Replace out_FragColor with gl_FragColor.
+    output = output.replaceAll(/out_FragColor/g, `gl_FragColor`);
+    output = output.replaceAll(/out_FragColor\[(\d+)\]/g, `gl_FragColor[$1]`);
+
+    if (/gl_FragDepth/.test(output)) {
+      output = `#extension GL_EXT_frag_depth : enable\n${output}`;
+      // Replace gl_FragDepth with gl_FragDepthEXT.
+      output = output.replaceAll(/gl_FragDepth/g, `gl_FragDepthEXT`);
+    }
+
+    // Enable the EXT_shader_texture_lod extension
+    output = `#ifdef GL_EXT_shader_texture_lod\n#extension GL_EXT_shader_texture_lod : enable\n#endif\n${output}`;
+    // Enable the OES_standard_derivatives extension
+    output = `#ifdef GL_OES_standard_derivatives\n#extension GL_OES_standard_derivatives : enable\n#endif\n${output}`;
+  } else {
+    // Replace the in with attribute.
+    output = output.replaceAll(/(in)\s+(vec\d|mat\d|float)/g, `attribute $2`);
+
+    // Replace the out with varying.
+    output = output.replaceAll(
+      /(out)\s+(vec\d|mat\d|float)\s+([\w]+);/g,
+      `varying $2 $3;`,
+    );
+  }
+
+  // Add version string for GLSL 1.00.
+  output = `#version 100\n${output}`;
+
+  return output;
+}
+
+export default demodernizeShader;