飞线，光照

src/Obj/Materail/FlowLineMaterialProperty.js

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+/*
+ * @Description: 流动线
+ */
+function FlowLine() {
+  class FlowLineMaterialProperty {
+    constructor(options) {
+      this._definitionChanged = new Cesium.Event();
+      this._color = undefined;
+      this._duration = undefined;
+      this.color = new Cesium.Color.fromCssColorString(options.color || "rgba(255,255,255,1)");
+      this.duration = options.duration || 10.0;
+      this.lineBackAlpha = options.lineBackAlpha || 0.05;
+    }
+
+    get isConstant() {
+      return false;
+    }
+
+    get definitionChanged() {
+      return this._definitionChanged;
+    }
+
+    getType(time) {
+      return Cesium.Material.FlowLineMaterialType;
+    }
+
+    getValue(time, result) {
+      if (!Cesium.defined(result)) {
+        result = {};
+      }
+
+      result.color = Cesium.Property.getValueOrDefault(
+        this._color,
+        time,
+        Cesium.Color.RED,
+        result.color
+      );
+      result.duration = Cesium.Property.getValueOrDefault(
+        this._duration,
+        time,
+        10,
+        result.duration
+      );
+      result.lineBackAlpha = this.lineBackAlpha;
+      result.frameNumber = Cesium.getTimestamp();
+      return result;
+    }
+
+    equals(other) {
+      return (
+        this === other ||
+        (other instanceof FlowLineMaterialProperty &&
+          Cesium.Property.equals(this._color, other._color) &&
+          Cesium.Property.equals(this._duration, other.duration) &&
+          Cesium.Property.equals(this.lineBackAlpha, other.lineBackAlpha))
+      );
+    }
+  }
+
+  Object.defineProperties(FlowLineMaterialProperty.prototype, {
+    color: Cesium.createPropertyDescriptor("color"),
+    duration: Cesium.createPropertyDescriptor("duration"),
+    transparency: Cesium.createPropertyDescriptor("lineBackAlpha"),
+  });
+
+  Cesium.FlowLineMaterialProperty = FlowLineMaterialProperty;
+  Cesium.Material.FlowLineMaterialProperty = "FlowLineMaterialProperty";
+  Cesium.Material.FlowLineMaterialType = "FlowLineMaterialType";
+  Cesium.Material.FlowLineMaterialSource = `
+      uniform vec4 color;
+      uniform float duration;
+      uniform float lineBackAlpha;
+
+      czm_material czm_getMaterial(czm_materialInput materialInput)
+        {
+            //生成默认的基础材质
+            czm_material material = czm_getDefaultMaterial(materialInput);
+            //获取st（uv）
+            vec2 st = materialInput.st;
+            //获取当前帧数，10秒内变化0-1
+            float time = fract(czm_frameNumber / (60.0*duration));
+            //长度1/10
+            time = time * (1.0 + 0.1);
+            //平滑过渡函数
+            float alpha = smoothstep(time-0.1,time,st.s) * step(-time,-st.s);
+            //光带轨迹（不会完全透明）
+            alpha += lineBackAlpha;
+            material.alpha = alpha;
+            material.diffuse = color.rgb;
+            return material;
+        }
+       `;
+
+  Cesium.Material._materialCache.addMaterial(
+    Cesium.Material.FlowLineMaterialType,
+    {
+      fabric: {
+        type: Cesium.Material.FlowLineMaterialType,
+        uniforms: {
+          color: new Cesium.Color(1.0, 1.0, 1.0, 1.0),
+          duration: 10.0,
+          lineBackAlpha: 0.05,
+        },
+        source: Cesium.Material.FlowLineMaterialSource,
+      },
+      translucent: function (material) {
+        return true;
+      },
+    }
+  );
+}
+
+export { FlowLine }