commit c50a03d78aaedd0003377e98710e7038bda330e9
author ztenghui <ztenghui@google.com> Thu Aug 21 13:47:54 2014 -0700
committer ztenghui <ztenghui@google.com> Fri Aug 22 13:51:16 2014 -0700
tree b52044852d73bd8d7e08bec4e3cda9be89aafed2
parent 730e9bceb746e6c50b87cc5a695eb73fea27686e

Improve the spot shadow computation.

Get rid of compuation of the intersection for penumbra and convex hull for umbra.
Use simple circle / normal to compute the penumbra and simple intersection for umbra.

The new way could be 2x to 4x faster from rectangle to round shape.
And this part is roughly half of the shadow computation, or 2/3 of spot shadow
computation.

This improve the spot shadow spikeness too.

b/16712006
b/14976551

Change-Id: I02911784868731369efa73f76fc915bc08248600

libs/hwui/SpotShadow.h

diff --git a/libs/hwui/SpotShadow.h b/libs/hwui/SpotShadow.h
index d65ea89..355be8d 100644
--- a/libs/hwui/SpotShadow.h
+++ b/libs/hwui/SpotShadow.h
@@ -26,16 +26,22 @@
 
 class SpotShadow {
 public:
-    static void createSpotShadow(bool isCasterOpaque, const Vector3* poly,
+    static void createSpotShadow_old(bool isCasterOpaque, const Vector3* poly,
             int polyLength, const Vector3& lightCenter, float lightSize,
             int lightVertexCount, VertexBuffer& retStrips);
+    static void createSpotShadow(bool isCasterOpaque, const Vector3& lightCenter,
+            float lightSize, const Vector3* poly, int polyLength,
+            const Vector3& polyCentroid, VertexBuffer& retstrips);
 
 private:
+    static float projectCasterToOutline(Vector2& outline,
+            const Vector3& lightCenter, const Vector3& polyVertex);
     static int calculateOccludedUmbra(const Vector2* umbra, int umbraLength,
             const Vector3* poly, int polyLength, Vector2* occludedUmbra);
-    static void computeSpotShadow(bool isCasterOpaque, const Vector3* lightPoly,
+
+    static void computeSpotShadow_old(bool isCasterOpaque, const Vector3* lightPoly,
             int lightPolyLength, const Vector3& lightCenter, const Vector3* poly,
-            int polyLength, VertexBuffer& retstrips);
+            int polyLength, VertexBuffer& shadowTriangleStrip);
 
     static void computeLightPolygon(int points, const Vector3& lightCenter,
             float size, Vector3* ret);
@@ -60,8 +66,8 @@
     static inline bool lineIntersection(double x1, double y1, double x2, double y2,
             double x3, double y3, double x4, double y4, Vector2& ret);
 
-    static void generateTriangleStrip(bool isCasterOpaque, const Vector2* penumbra,
-            int penumbraLength, const Vector2* umbra, int umbraLength,
+    static void generateTriangleStrip(bool isCasterOpaque, float shadowStrengthScale,
+            const Vector2* penumbra, int penumbraLength, const Vector2* umbra, int umbraLength,
             const Vector3* poly, int polyLength, VertexBuffer& retstrips);
 
 #if DEBUG_SHADOW
@@ -72,6 +78,8 @@
         const Vector2* poly2, int poly2Length,
         const Vector2* intersection, int intersectionLength);
     static void updateBound(const Vector2 inVector, Vector2& lowerBound, Vector2& upperBound );
+    static void dumpPolygon(const Vector2* poly, int polyLength, const char* polyName);
+    static void dumpPolygon(const Vector3* poly, int polyLength, const char* polyName);
 #endif
 
 }; // SpotShadow