API change to allow for NormalSource selection at the user level.

gm/lightingshader.cpp

Index: gm/lightingshader.cpp
diff --git a/gm/lightingshader.cpp b/gm/lightingshader.cpp
index ae6a24f9f0c3ce895aeae048f022c53ce0504daf..19237f78fa16a35328c22532362635ab83363a6c 100644
--- a/gm/lightingshader.cpp
+++ b/gm/lightingshader.cpp
@@ -7,7 +7,9 @@
 
 #include "gm.h"
 
+#include "SkBitmapProcShader.h"
 #include "SkLightingShader.h"
+#include "SkNormalSource.h"
 #include "SkPoint3.h"
 #include "SkShader.h"
 
@@ -49,7 +51,7 @@ public:
         SkLights::Builder builder;
 
         builder.add(SkLights::Light(SkColor3f::Make(1.0f, 1.0f, 1.0f),

[robertphillips, 2016/07/06 16:36:33]

I think you want this to be normalized: 
 (SK_ScalarRoot2Over2, 0.0f, SK_ScalarRoot2Over2)
?

[dvonbeck, 2016/07/06 18:07:48]

It gets normalized by the constructor, should I still change it?

[robertphillips, 2016/07/06 19:11:13]

It will probably make more sense to the reader. Otherwise they have to normalize
it in their heads to figure out where to expect the light.

[dvonbeck, 2016/07/06 19:34:36]

Done.

-                                    SkVector3::Make(1.0f, 0.0f, 0.0f)));
+                                    SkVector3::Make(1.0f, 0.0f, 0.6f)));
         builder.add(SkLights::Light(SkColor3f::Make(0.2f, 0.2f, 0.2f)));
 
         fLights = builder.finish();
@@ -95,12 +97,13 @@ protected:
 
         const SkMatrix& ctm = canvas->getTotalMatrix();
 
-        // TODO: correctly pull out the pure rotation
-        SkVector invNormRotation = { ctm[SkMatrix::kMScaleX], ctm[SkMatrix::kMSkewY] };
-
         SkPaint paint;
-        paint.setShader(SkLightingShader::Make(fDiffuse, fNormalMaps[mapType], fLights,
-                                               invNormRotation, &matrix, &matrix));
+        sk_sp<SkShader> normalMap = SkMakeBitmapShader(fNormalMaps[mapType],
+                SkShader::kClamp_TileMode, SkShader::kClamp_TileMode, &matrix, nullptr);
+        sk_sp<SkNormalSource> normalSource = SkNormalSource::MakeFromNormalMap(std::move(normalMap),
+                                                                               ctm);
+        paint.setShader(SkLightingShader::Make(fDiffuse, fLights, &matrix,
+                                               std::move(normalSource)));
 
         canvas->drawRect(r, paint);
     }