Add existing to tracked

node_modules/@cesium/engine/Source/Shaders/Materials/FadeMaterial.glsl

@@ -0,0 +1,37 @@
+uniform vec4 fadeInColor;
+uniform vec4 fadeOutColor;
+uniform float maximumDistance;
+uniform bool repeat;
+uniform vec2 fadeDirection;
+uniform vec2 time;
+
+float getTime(float t, float coord)
+{
+    float scalar = 1.0 / maximumDistance;
+    float q  = distance(t, coord) * scalar;
+    if (repeat)
+    {
+        float r = distance(t, coord + 1.0) * scalar;
+        float s = distance(t, coord - 1.0) * scalar;
+        q = min(min(r, s), q);
+    }
+    return clamp(q, 0.0, 1.0);
+}
+
+czm_material czm_getMaterial(czm_materialInput materialInput)
+{
+    czm_material material = czm_getDefaultMaterial(materialInput);
+
+    vec2 st = materialInput.st;
+    float s = getTime(time.x, st.s) * fadeDirection.s;
+    float t = getTime(time.y, st.t) * fadeDirection.t;
+
+    float u = length(vec2(s, t));
+    vec4 color = mix(fadeInColor, fadeOutColor, u);
+
+    color = czm_gammaCorrect(color);
+    material.emission = color.rgb;
+    material.alpha = color.a;
+
+    return material;
+}