1 files changed, 40 insertions, 1 deletions
diff --git a/libs/hwui/ShadowTessellator.h b/libs/hwui/ShadowTessellator.h
index ef95609..c49fdcb 100644
--- a/libs/hwui/ShadowTessellator.h
+++ b/libs/hwui/ShadowTessellator.h
@@ -20,18 +20,57 @@
 
 #include "Debug.h"
 #include "Matrix.h"
+#include "VertexBuffer.h"
 
 namespace android {
 namespace uirenderer {
 
+// All SHADOW_* are used to define all the geometry property of shadows.
+// Use a simplified example to illustrate the geometry setup here.
+// Assuming we use 6 rays and only 1 layer, Then we will have 2 hexagons, which
+// are 0 to 5 and 6 to 11. The area between them will be the penumbra area, and
+// the area inside the 2nd hexagon is the umbra.
+// Also, we need to add the centroid "12" to draw the umbra area as triangle fans.
+//
+// Triange strip indices for penumbra area: (0, 6, 1, 7, 2, 8, 3, 9, 4, 10, 5, 11, 0, 6)
+// Triange strip indices for numbra area: (6, 12, 7, 12, 8, 12, 9, 12, 10, 12, 11, 12, 6)
+//                 0
+//
+//      5          6         1
+//           11         7
+//                12
+//           10         8
+//      4          9         2
+//
+//                 3
+
+// The total number of rays starting from the centroid of shadow area, in order
+// to generate the shadow geometry.
+#define SHADOW_RAY_COUNT 256
+
+// The total number of layers in the outer shadow area, 1 being the minimum.
+#define SHADOW_LAYER_COUNT 2
+
+// The total number of all the vertices representing the shadow.
+#define SHADOW_VERTEX_COUNT ((SHADOW_LAYER_COUNT + 1) * SHADOW_RAY_COUNT + 1)
+
+// The total number of indices used for drawing the shadow geometry as triangle strips.
+#define SHADOW_INDEX_COUNT (2 * SHADOW_RAY_COUNT + 1 + 2 * (SHADOW_RAY_COUNT + 1) * \
+        SHADOW_LAYER_COUNT)
+
 class ShadowTessellator {
 public:
-    static void tessellateAmbientShadow(const Vector3* casterPolygon, int casterVertexCount,
+    static void tessellateAmbientShadow(const Vector3* casterPolygon,
+            int casterVertexCount, const Vector3& centroid3d,
             VertexBuffer& shadowVertexBuffer);
 
     static void tessellateSpotShadow(const Vector3* casterPolygon, int casterVertexCount,
             const Vector3& lightPosScale, const mat4& receiverTransform,
             int screenWidth, int screenHeight, VertexBuffer& shadowVertexBuffer);
+
+    static void generateShadowIndices(uint16_t*  shadowIndices);
+
+    static Vector2 centroid2d(const Vector2* poly, int polyLength);
 }; // ShadowTessellator
 
 }; // namespace uirenderer