Add existing to tracked

node_modules/@cesium/engine/Source/Scene/Splitter.js

@@ -0,0 +1,49 @@
+import ShaderSource from "../Renderer/ShaderSource.js";
+
+/**
+ * Support for rendering things on only one side of the screen.
+ *
+ * @private
+ */
+const Splitter = {
+  /**
+   * Given a fragment shader string, returns a modified version of it that
+   * only renders on one side of the screen or the other. Fragments on the
+   * other side are discarded. The screen side is given by a uniform called
+   * `czm_splitDirection`, which can be added by calling
+   * {@link Splitter#addUniforms}, and the split position is given by an
+   * automatic uniform called `czm_splitPosition`.
+   */
+  modifyFragmentShader: function modifyFragmentShader(shader) {
+    shader = ShaderSource.replaceMain(shader, "czm_splitter_main");
+    shader +=
+      // czm_splitPosition is not declared because it is an automatic uniform.
+      "uniform float czm_splitDirection; \n" +
+      "void main() \n" +
+      "{ \n" +
+      // Don't split when rendering the shadow map, because it is rendered from
+      // the perspective of a totally different camera.
+      "#ifndef SHADOW_MAP\n" +
+      "    if (czm_splitDirection < 0.0 && gl_FragCoord.x > czm_splitPosition) discard; \n" +
+      "    if (czm_splitDirection > 0.0 && gl_FragCoord.x < czm_splitPosition) discard; \n" +
+      "#endif\n" +
+      "    czm_splitter_main(); \n" +
+      "} \n";
+
+    return shader;
+  },
+
+  /**
+   * Add `czm_splitDirection` to the given uniform map.
+   *
+   * @param {object} object The object on which the `splitDirection` property may be found.
+   * @param {object} uniformMap The uniform map.
+   */
+  addUniforms: function addUniforms(object, uniformMap) {
+    uniformMap.czm_splitDirection = function () {
+      return object.splitDirection;
+    };
+  },
+};
+
+export default Splitter;