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diff --git a/libs/hwui/AmbientShadow.h b/libs/hwui/AmbientShadow.h
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+
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_HWUI_AMBIENT_SHADOW_H
+#define ANDROID_HWUI_AMBIENT_SHADOW_H
+
+#include "Debug.h"
+#include "Vector.h"
+#include "VertexBuffer.h"
+
+namespace android {
+namespace uirenderer {
+
+/**
+ * AmbientShadow is used to calculate the ambient shadow value around a polygon.
+ *
+ * TODO: calculateIntersection() now is O(N*M), where N is the number of
+ * polygon's vertics and M is the number of rays. In fact, by staring tracing
+ * the vertex from the previous intersection, the algorithm can be O(N + M);
+ */
+class AmbientShadow {
+public:
+    static void createAmbientShadow(const Vector3* poly, int polyLength, int rays,
+            int layers, float strength, float heightFactor, float geomFactor,
+            VertexBuffer& shadowVertexBuffer);
+
+private:
+    static void calculatePolygonCentroid(const Vector3* poly, int len, Vector2& centroid);
+
+    static void calculateRayDirections(int rays, Vector2* dir);
+
+    static void calculateIntersection(const Vector3* poly, int nbVertices,
+            const Vector2& start, const Vector2& dir, int& outEdgeIndex,
+            float& outEdgeFraction, float& outRayDist);
+
+    static void calculateNormal(int rays, int currentRayIndex, const Vector2* dir,
+            const float* rayDist, Vector2& normal);
+}; // AmbientShadow
+
+}; // namespace uirenderer
+}; // namespace android
+
+#endif // ANDROID_HWUI_AMBIENT_SHADOW_H