commit bf75945e7a1ae7c1000682716643c942c1e19ba6
author Chris Craik <ccraik@google.com> Mon Aug 11 16:00:44 2014 -0700
committer Chris Craik <ccraik@google.com> Tue Aug 12 12:44:59 2014 -0700
tree 5be8c8acfb85bb0a6077691e2c0255232cace2ae
parent c28aceb11e736382bc7ee749483ea5f23299ad78

Rework shadow interpolation

bug:16852257

Use pow(alpha, 1.5) to avoid harsh edges on shadow alpha ramps.

Also adjusts shadow constants to compensate.

Change-Id: I5869956d7d292db2a8e496bc320084b6d64c3fb7

libs/hwui/ProgramCache.cpp

diff --git a/libs/hwui/ProgramCache.cpp b/libs/hwui/ProgramCache.cpp
index 3ef2a71..2dd89b8 100644
--- a/libs/hwui/ProgramCache.cpp
+++ b/libs/hwui/ProgramCache.cpp
@@ -121,8 +121,12 @@
 const char* gVS_Main_Position =
         "    vec4 transformedPosition = projection * transform * position;\n"
         "    gl_Position = transformedPosition;\n";
+
+const char* gVS_Main_ShadowAAVertexShape =
+        "    alpha = pow(vtxAlpha, 0.667);\n";
 const char* gVS_Main_AAVertexShape =
         "    alpha = vtxAlpha;\n";
+
 const char* gVS_Main_HasRoundRectClip =
         "    roundRectPos = (roundRectInvTransform * transformedPosition).xy;\n";
 const char* gVS_Footer =
@@ -237,6 +241,8 @@
         "    fragColor *= color.a;\n";
 const char* gFS_Main_AccountForAAVertexShape =
         "    fragColor *= alpha;\n";
+const char* gFS_Main_AccountForShadowAAVertexShape =
+        "    fragColor *= pow(alpha, 1.5);\n";
 
 const char* gFS_Main_FetchTexture[2] = {
         // Don't modulate
@@ -515,7 +521,11 @@
             shader.append(gVS_Main_OutTexCoords);
         }
         if (description.isAA) {
-            shader.append(gVS_Main_AAVertexShape);
+            if (description.isShadowAA) {
+                shader.append(gVS_Main_ShadowAAVertexShape);
+            } else {
+                shader.append(gVS_Main_AAVertexShape);
+            }
         }
         if (description.hasColors) {
             shader.append(gVS_Main_OutColors);
@@ -750,7 +760,11 @@
         shader.append(gFS_Main_ApplyColorOp[description.colorOp]);
 
         if (description.isAA) {
-            shader.append(gFS_Main_AccountForAAVertexShape);
+            if (description.isShadowAA) {
+                shader.append(gFS_Main_AccountForShadowAAVertexShape);
+            } else {
+                shader.append(gFS_Main_AccountForAAVertexShape);
+            }
         }
 
         // Output the fragment