Add existing to tracked

node_modules/@cesium/engine/Source/Scene/Model/CustomShaderMode.js

@@ -0,0 +1,42 @@
+/**
+ * An enum describing how the {@link CustomShader} will be added to the
+ * fragment shader. This determines how the shader interacts with the material.
+ *
+ * @enum {string}
+ *
+ * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
+ */
+const CustomShaderMode = {
+  /**
+   * The custom shader will be used to modify the results of the material stage
+   * before lighting is applied.
+   *
+   * @type {string}
+   * @constant
+   */
+  MODIFY_MATERIAL: "MODIFY_MATERIAL",
+  /**
+   * The custom shader will be used instead of the material stage. This is a hint
+   * to optimize out the material processing code.
+   *
+   * @type {string}
+   * @constant
+   */
+  REPLACE_MATERIAL: "REPLACE_MATERIAL",
+};
+
+/**
+ * Convert the shader mode to an uppercase identifier for use in GLSL define
+ * directives. For example:  <code>#define CUSTOM_SHADER_MODIFY_MATERIAL</code>
+ * @param {CustomShaderMode} customShaderMode The shader mode
+ * @return {string} The name of the GLSL macro to use
+ *
+ * @private
+ */
+CustomShaderMode.getDefineName = function (customShaderMode) {
+  return `CUSTOM_SHADER_${customShaderMode}`;
+};
+
+Object.freeze(CustomShaderMode);
+
+export default CustomShaderMode;