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

samplecode/SampleLitAtlas.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SampleCode.h"
 #include "SkAnimTimer.h"
-#include "SkView.h"
+#include "SkBitmapProcShader.h"
 #include "SkCanvas.h"
 #include "SkDrawable.h"
 #include "SkLightingShader.h"
 #include "SkLights.h"
+#include "SkNormalSource.h"
 #include "SkRandom.h"
 #include "SkRSXform.h"
+#include "SkView.h"
 
 #include "sk_tool_utils.h"
 
 class DrawLitAtlasDrawable : public SkDrawable {
 public:
     DrawLitAtlasDrawable(const SkRect& r)
         : fBounds(r)
         , fUseColors(false)
         , fLightDir(SkVector3::Make(1.0f, 0.0f, 0.0f)) {
         fAtlas = MakeAtlas();
@@ skipping 94 matching lines @@
 
             SkRect r = fDiffTex[i];
             r.offsetTo(0, 0);
 
             diffMat.setRectToRect(fDiffTex[i], r, SkMatrix::kFill_ScaleToFit);
             normalMat.setRectToRect(fNormTex[i], r, SkMatrix::kFill_ScaleToFit);
 
             SkMatrix m;
             m.setRSXform(xforms[i]);
 
-            // TODO: correctly pull out the pure rotation
-            SkVector invNormRotation = { m[SkMatrix::kMScaleX], m[SkMatrix::kMSkewY] };
-            SkASSERT(SkScalarNearlyEqual(invNormRotation.lengthSqd(), SK_Scalar1));
-
-            paint.setShader(SkLightingShader::Make(fAtlas, fAtlas, fLights,
-                                                   invNormRotation, &diffMat, &normalMat));
+            sk_sp<SkShader> normalMap = SkMakeBitmapShader(fAtlas, SkShader::kClamp_TileMode,
+                    SkShader::kClamp_TileMode, &normalMat, nullptr);
+            sk_sp<SkNormalSource> normalSource = SkNormalSource::MakeFromNormalMap(
+                    std::move(normalMap), m);
+            paint.setShader(SkLightingShader::Make(fAtlas, fLights, &diffMat,
+                                                   std::move(normalSource)));
 
             canvas->save();
                 canvas->setMatrix(m);
                 canvas->drawRect(r, paint);
             canvas->restore();
         }
 #endif
 
 #ifdef SK_DEBUG
         {
@@ skipping 356 matching lines @@
 private:
     SkAutoTUnref<DrawLitAtlasDrawable> fDrawable;
 
     typedef SampleView INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static SkView* MyFactory() { return new DrawLitAtlasView; }
 static SkViewRegister reg(MyFactory);