Update SkLightingShader to support rotation

src/core/SkLightingShader.cpp

 
 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapProcState.h"
 #include "SkColor.h"
 #include "SkEmptyShader.h"
 #include "SkErrorInternals.h"
 #include "SkLightingShader.h"
 #include "SkMathPriv.h"
+#include "SkPoint3.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 
 ////////////////////////////////////////////////////////////////////////////
 
 /*
    SkLightingShader TODOs:
         support other than clamp mode
         allow 'diffuse' & 'normal' to be of different dimensions?
         support different light types
         support multiple lights
         enforce normal map is 4 channel
         use SkImages instead if SkBitmaps
 
     To Test:
         non-opaque diffuse textures
         A8 diffuse textures
         down & upsampled draws
 */
 
 
 
 /** \class SkLightingShaderImpl
     This subclass of shader applies lighting.
 */
 class SK_API SkLightingShaderImpl : public SkShader {
 public:
 
-    /** Create a new lighting shader that use the provided normal map, light
-        and ambient color to light the diffuse bitmap.
-        @param diffuse the diffuse bitmap
-        @param normal  the normal map
-        @param light   the light applied to the normal map
-        @param ambient the linear (unpremul) ambient light color
+    /** Create a new lighting shader that uses the provided normal map and
+        lights to light the diffuse bitmap.
+        @param diffuse    the diffuse bitmap
+        @param normal     the normal map
+        @param lights     the lights applied to the normal map
+        @param invNormRotation rotation applied to the normal map's normals
+        @param diffLocalM the local matrix for the diffuse coordinates
+        @param normLocalM the local matrix for the normal coordinates
     */
     SkLightingShaderImpl(const SkBitmap& diffuse, const SkBitmap& normal,
-                         const SkLightingShader::Light& light,
-                         const SkColor3f& ambient, const SkMatrix* localMatrix) 
-        : INHERITED(localMatrix)
+                         const SkLightingShader::Lights* lights,
+                         const SkVector& invNormRotation,
+                         const SkMatrix* diffLocalM, const SkMatrix* normLocalM) 
+        : INHERITED(diffLocalM)
         , fDiffuseMap(diffuse)
         , fNormalMap(normal)
-        , fLight(light)
-        , fAmbientColor(ambient) {
-        if (!fLight.fDirection.normalize()) {
-            fLight.fDirection = SkPoint3::Make(0.0f, 0.0f, 1.0f);
+        , fLights(SkRef(lights))
+        , fInvNormRotation(invNormRotation) {
+
+        if (normLocalM) {
+            fNormLocalMatrix = *normLocalM;
+        } else {
+            fNormLocalMatrix.reset();
         }
+        // Pre-cache so future calls to fNormLocalMatrix.getType() are threadsafe.
+        (void)fNormLocalMatrix.getType();
+
     }
 
     bool isOpaque() const override;
 
     bool asFragmentProcessor(GrContext*, const SkPaint& paint, const SkMatrix& viewM,
                              const SkMatrix* localMatrix, GrColor* color,
                              GrProcessorDataManager*, GrFragmentProcessor** fp) const override;
 
     size_t contextSize() const override;
 
@@ skipping 16 matching lines @@
 
         typedef SkShader::Context INHERITED;
     };
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkLightingShaderImpl)
 
 protected:
     void flatten(SkWriteBuffer&) const override;
     Context* onCreateContext(const ContextRec&, void*) const override;
+    bool computeNormTotalInverse(const ContextRec& rec, SkMatrix* normTotalInverse) const;
 
 private:
-    SkBitmap                fDiffuseMap;
-    SkBitmap                fNormalMap;
-    SkLightingShader::Light fLight;
-    SkColor3f               fAmbientColor;  // linear (unpremul) color. Range is 0..1/channel.
+    SkBitmap  fDiffuseMap;
+    SkBitmap  fNormalMap;
+
+    SkAutoTUnref<const SkLightingShader::Lights>   fLights;
+
+    SkMatrix  fNormLocalMatrix;
+    SkVector  fInvNormRotation;
 
     friend class SkLightingShader;
 
     typedef SkShader INHERITED;
 };
 
 ////////////////////////////////////////////////////////////////////////////
 
 #if SK_SUPPORT_GPU
 
 #include "GrCoordTransform.h"
 #include "GrFragmentProcessor.h"
 #include "GrTextureAccess.h"
 #include "gl/GrGLProcessor.h"
 #include "gl/builders/GrGLProgramBuilder.h"
 #include "SkGr.h"
 
 class LightingFP : public GrFragmentProcessor {
 public:
-    LightingFP(GrTexture* diffuse, GrTexture* normal, const SkMatrix& matrix,
-               const SkVector3& lightDir, const SkColor3f& lightColor,
-               const SkColor3f& ambientColor)
-        : fDeviceTransform(kDevice_GrCoordSet, matrix)
-        , fDiffuseTextureAccess(diffuse)
-        , fNormalTextureAccess(normal)
-        , fLightDir(lightDir)
-        , fLightColor(lightColor)
-        , fAmbientColor(ambientColor) {
-        this->addCoordTransform(&fDeviceTransform);
+    LightingFP(GrProcessorDataManager* pdm, GrTexture* diffuse, GrTexture* normal,
+               const SkMatrix& diffMatrix, const SkMatrix& normMatrix,
+               const GrTextureParams& diffParams, const GrTextureParams& normParams,
+               const SkLightingShader::Lights* lights, const SkVector& invNormRotation)
+        : fDiffDeviceTransform(kLocal_GrCoordSet, diffMatrix, diffuse, diffParams.filterMode())
+        , fNormDeviceTransform(kLocal_GrCoordSet, normMatrix, normal, normParams.filterMode())
+        , fDiffuseTextureAccess(diffuse, diffParams)
+        , fNormalTextureAccess(normal, normParams)
+        , fInvNormRotation(invNormRotation) {
+        this->addCoordTransform(&fDiffDeviceTransform);
+        this->addCoordTransform(&fNormDeviceTransform);
         this->addTextureAccess(&fDiffuseTextureAccess);
         this->addTextureAccess(&fNormalTextureAccess);
 
+        // fuse all ambient lights into a single one
+        fAmbientColor.set(0.0f, 0.0f, 0.0f);
+        for (int i = 0; i < lights->numLights(); ++i) {
+            if (SkLight::kAmbient_LightType == lights->light(i).type()) {
+                fAmbientColor += lights->light(i).color();
+            } else {
+                // TODO: handle more than one of these
+                fLightColor = lights->light(i).color();
+                fLightDir = lights->light(i).dir();
+            }
+        }
+
         this->initClassID<LightingFP>();
     }
 
     class LightingGLFP : public GrGLFragmentProcessor {
     public:
         LightingGLFP() {
             fLightDir.fX = 10000.0f;
             fLightColor.fX = 0.0f;
             fAmbientColor.fX = 0.0f;
+            fInvNormRotation.fX = 0.0f;
         }
 
         void emitCode(EmitArgs& args) override {
 
             GrGLFragmentBuilder* fpb = args.fBuilder->getFragmentShaderBuilder();
 
             // add uniforms
             const char* lightDirUniName = NULL;
             fLightDirUni = args.fBuilder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                                      kVec3f_GrSLType, kDefault_GrSLPrecision,
                                                      "LightDir", &lightDirUniName);
 
             const char* lightColorUniName = NULL;
             fLightColorUni = args.fBuilder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                                        kVec3f_GrSLType, kDefault_GrSLPrecision,
                                                        "LightColor", &lightColorUniName);
 
             const char* ambientColorUniName = NULL;
             fAmbientColorUni = args.fBuilder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                                          kVec3f_GrSLType, kDefault_GrSLPrecision,
                                                          "AmbientColor", &ambientColorUniName);
 
+            const char* xformUniName = NULL;
+            fXformUni = args.fBuilder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
+                                                  kVec2f_GrSLType, kDefault_GrSLPrecision,
+                                                  "Xform", &xformUniName);
+
             fpb->codeAppend("vec4 diffuseColor = ");
             fpb->appendTextureLookupAndModulate(args.fInputColor, args.fSamplers[0], 
                                                 args.fCoords[0].c_str(), 
                                                 args.fCoords[0].getType());
             fpb->codeAppend(";");
 
             fpb->codeAppend("vec4 normalColor = ");
             fpb->appendTextureLookup(args.fSamplers[1],
-                                     args.fCoords[0].c_str(), 
-                                     args.fCoords[0].getType());
+                                     args.fCoords[1].c_str(), 
+                                     args.fCoords[1].getType());
             fpb->codeAppend(";");
 
-            fpb->codeAppend("vec3 normal = normalize(normalColor.rgb - vec3(0.5));");
-            fpb->codeAppendf("vec3 lightDir = normalize(%s);", lightDirUniName);
-            fpb->codeAppend("float NdotL = dot(normal, lightDir);");
+            fpb->codeAppend("vec3 normal = normalColor.rgb - vec3(0.5);");
+
+            fpb->codeAppendf("mat3 m = mat3(%s.x, -%s.y, 0.0, %s.y, %s.x, 0.0, 0.0, 0.0, 1.0);",
+                             xformUniName, xformUniName, xformUniName, xformUniName);
+            
+            fpb->codeAppend("normal = normalize(m*normal);");

[jvanverth1, 2015/08/19 13:57:48]

It's more efficient to multiply the light direction by the transpose of the
normal matrix in the vertex shader (i.e. transform the light direction from
world space into object space, rather than transform all the normals from object
space into world space). Or perhaps just pre-transform the light direction on
the CPU before setting the uniform.

[robertphillips, 2015/08/19 16:17:57]

I've added a TODO.

+
+            fpb->codeAppendf("float NdotL = clamp(dot(normal, %s), 0.0, 1.0);", lightDirUniName);
             // diffuse light
             fpb->codeAppendf("vec3 result = %s*diffuseColor.rgb*NdotL;", lightColorUniName);
             // ambient light
             fpb->codeAppendf("result += %s;", ambientColorUniName);
             fpb->codeAppendf("%s = vec4(result.rgb, diffuseColor.a);", args.fOutputColor);
         }
 
         void setData(const GrGLProgramDataManager& pdman, const GrProcessor& proc) override {
             const LightingFP& lightingFP = proc.cast<LightingFP>();
 
             const SkVector3& lightDir = lightingFP.lightDir();
             if (lightDir != fLightDir) {
                 pdman.set3fv(fLightDirUni, 1, &lightDir.fX);
                 fLightDir = lightDir;
             }
 
             const SkColor3f& lightColor = lightingFP.lightColor();
             if (lightColor != fLightColor) {
                 pdman.set3fv(fLightColorUni, 1, &lightColor.fX);
                 fLightColor = lightColor;
             }
 
             const SkColor3f& ambientColor = lightingFP.ambientColor();
             if (ambientColor != fAmbientColor) {
                 pdman.set3fv(fAmbientColorUni, 1, &ambientColor.fX);
                 fAmbientColor = ambientColor;
             }
+
+            const SkVector& invNormRotation = lightingFP.invNormRotation();
+            if (invNormRotation != fInvNormRotation) {
+                pdman.set2fv(fXformUni, 1, &invNormRotation.fX);
+                fInvNormRotation = invNormRotation;
+            }
         }
 
         static void GenKey(const GrProcessor& proc, const GrGLSLCaps&,
                            GrProcessorKeyBuilder* b) {
 //            const LightingFP& lightingFP = proc.cast<LightingFP>();
             // only one shader generated currently
             b->add32(0x0);
         }
 
     private:
         SkVector3 fLightDir;
         GrGLProgramDataManager::UniformHandle fLightDirUni;
 
         SkColor3f fLightColor;
         GrGLProgramDataManager::UniformHandle fLightColorUni;
 
         SkColor3f fAmbientColor;
         GrGLProgramDataManager::UniformHandle fAmbientColorUni;
+
+        SkVector fInvNormRotation;
+        GrGLProgramDataManager::UniformHandle fXformUni;
     };
 
     GrGLFragmentProcessor* createGLInstance() const override { return SkNEW(LightingGLFP); }
 
     void onGetGLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override {
         LightingGLFP::GenKey(*this, caps, b);
     }
 
     const char* name() const override { return "LightingFP"; }
 
     void onComputeInvariantOutput(GrInvariantOutput* inout) const override {
         inout->mulByUnknownFourComponents();
     }
 
     const SkVector3& lightDir() const { return fLightDir; }
     const SkColor3f& lightColor() const { return fLightColor; }
     const SkColor3f& ambientColor() const { return fAmbientColor; }
+    const SkVector& invNormRotation() const { return fInvNormRotation; }
 
 private:
     bool onIsEqual(const GrFragmentProcessor& proc) const override { 
         const LightingFP& lightingFP = proc.cast<LightingFP>();
-        return fDeviceTransform == lightingFP.fDeviceTransform &&
+        return fDiffDeviceTransform == lightingFP.fDiffDeviceTransform &&
+               fNormDeviceTransform == lightingFP.fNormDeviceTransform &&
                fDiffuseTextureAccess == lightingFP.fDiffuseTextureAccess &&
                fNormalTextureAccess == lightingFP.fNormalTextureAccess &&
                fLightDir == lightingFP.fLightDir &&
                fLightColor == lightingFP.fLightColor &&
-               fAmbientColor == lightingFP.fAmbientColor;
+               fAmbientColor == lightingFP.fAmbientColor &&
+               fInvNormRotation == lightingFP.fInvNormRotation;
     }
 
-    GrCoordTransform fDeviceTransform;
+    GrCoordTransform fDiffDeviceTransform;
+    GrCoordTransform fNormDeviceTransform;
     GrTextureAccess  fDiffuseTextureAccess;
     GrTextureAccess  fNormalTextureAccess;
     SkVector3        fLightDir;
     SkColor3f        fLightColor;
     SkColor3f        fAmbientColor;
+
+    SkVector         fInvNormRotation;
 };
 
 ////////////////////////////////////////////////////////////////////////////
 
-bool SkLightingShaderImpl::asFragmentProcessor(GrContext* context, const SkPaint& paint, 
-                                               const SkMatrix& viewM, const SkMatrix* localMatrix, 
-                                               GrColor* color, GrProcessorDataManager*,
-                                               GrFragmentProcessor** fp) const {
-    // we assume diffuse and normal maps have same width and height
-    // TODO: support different sizes
-    SkASSERT(fDiffuseMap.width() == fNormalMap.width() &&
-             fDiffuseMap.height() == fNormalMap.height());
-    SkMatrix matrix;
-    matrix.setIDiv(fDiffuseMap.width(), fDiffuseMap.height());
+static bool make_mat(const SkBitmap& bm,
+                     const SkMatrix& localMatrix1,
+                     const SkMatrix* localMatrix2,
+                     SkMatrix* result) {
+    
+    result->setIDiv(bm.width(), bm.height());
 
     SkMatrix lmInverse;
-    if (!this->getLocalMatrix().invert(&lmInverse)) {
+    if (!localMatrix1.invert(&lmInverse)) {
         return false;
     }
-    if (localMatrix) {
+    if (localMatrix2) {
         SkMatrix inv;
-        if (!localMatrix->invert(&inv)) {
+        if (!localMatrix2->invert(&inv)) {
             return false;
         }
         lmInverse.postConcat(inv);
     }
-    matrix.preConcat(lmInverse);
+    result->preConcat(lmInverse);
 
+    return true;
+}
+
+static  GrTextureParams::FilterMode pick_filter_level(SkFilterQuality filterIn,
+                                                      const SkMatrix& viewM,
+                                                      const SkMatrix& localM) {
     // Must set wrap and filter on the sampler before requesting a texture. In two places below
     // we check the matrix scale factors to determine how to interpret the filter quality setting.
     // This completely ignores the complexity of the drawVertices case where explicit local coords
     // are provided by the caller.
     GrTextureParams::FilterMode textureFilterMode = GrTextureParams::kBilerp_FilterMode;
-    switch (paint.getFilterQuality()) {
+    switch (filterIn) {
     case kNone_SkFilterQuality:
         textureFilterMode = GrTextureParams::kNone_FilterMode;
         break;
     case kLow_SkFilterQuality:
         textureFilterMode = GrTextureParams::kBilerp_FilterMode;
         break;
-    case kMedium_SkFilterQuality:{                          
+    case kMedium_SkFilterQuality:{
         SkMatrix matrix;
-        matrix.setConcat(viewM, this->getLocalMatrix());
+        matrix.setConcat(viewM, localM);
         if (matrix.getMinScale() < SK_Scalar1) {
             textureFilterMode = GrTextureParams::kMipMap_FilterMode;
         } else {
             // Don't trigger MIP level generation unnecessarily.
             textureFilterMode = GrTextureParams::kBilerp_FilterMode;
         }
         break;
     }
     case kHigh_SkFilterQuality:
     default:
         SkErrorInternals::SetError(kInvalidPaint_SkError,
             "Sorry, I don't understand the filtering "
             "mode you asked for.  Falling back to "
             "MIPMaps.");
         textureFilterMode = GrTextureParams::kMipMap_FilterMode;
         break;
 
     }
 
+    return textureFilterMode;
+}
+
+bool SkLightingShaderImpl::asFragmentProcessor(GrContext* context, const SkPaint& paint, 
+                                               const SkMatrix& viewM, const SkMatrix* localMatrix, 
+                                               GrColor* color, GrProcessorDataManager* pdm,
+                                               GrFragmentProcessor** fp) const {
+    // we assume diffuse and normal maps have same width and height
+    // TODO: support different sizes
+    SkASSERT(fDiffuseMap.width() == fNormalMap.width() &&
+             fDiffuseMap.height() == fNormalMap.height());
+    SkMatrix diffM, normM;
+    
+    if (!make_mat(fDiffuseMap, this->getLocalMatrix(), localMatrix, &diffM)) {
+        return false;    
+    }
+
+    if (!make_mat(fNormalMap, fNormLocalMatrix, localMatrix, &normM)) {
+        return false;
+    }
+
+    GrTextureParams::FilterMode diffFilterMode = pick_filter_level(paint.getFilterQuality(), 
+                                                                   viewM,
+                                                                   this->getLocalMatrix()); 
+
+    GrTextureParams::FilterMode normFilterMode = pick_filter_level(paint.getFilterQuality(), 
+                                                                   viewM,
+                                                                   fNormLocalMatrix); 
+
     // TODO: support other tile modes
-    GrTextureParams params(kClamp_TileMode, textureFilterMode);
-    SkAutoTUnref<GrTexture> diffuseTexture(GrRefCachedBitmapTexture(context, fDiffuseMap, &params));
+    GrTextureParams diffParams(kClamp_TileMode, diffFilterMode);
+    SkAutoTUnref<GrTexture> diffuseTexture(GrRefCachedBitmapTexture(context,
+                                                                    fDiffuseMap, &diffParams));
     if (!diffuseTexture) {
         SkErrorInternals::SetError(kInternalError_SkError,
             "Couldn't convert bitmap to texture.");
         return false;
     }
 
-    SkAutoTUnref<GrTexture> normalTexture(GrRefCachedBitmapTexture(context, fNormalMap, &params));
+    GrTextureParams normParams(kClamp_TileMode, normFilterMode);
+    SkAutoTUnref<GrTexture> normalTexture(GrRefCachedBitmapTexture(context,
+                                                                   fNormalMap, &normParams));
     if (!normalTexture) {
         SkErrorInternals::SetError(kInternalError_SkError,
             "Couldn't convert bitmap to texture.");
         return false;
     }
 
-    *fp = SkNEW_ARGS(LightingFP, (diffuseTexture, normalTexture, matrix,
-                                  fLight.fDirection, fLight.fColor, fAmbientColor));
+
+    *fp = SkNEW_ARGS(LightingFP, (pdm, diffuseTexture, normalTexture,
+                                  diffM, normM, diffParams, normParams, fLights,
+                                  fInvNormRotation));
+
     *color = GrColorPackA4(paint.getAlpha());
     return true;
 }
 #else
 
 bool SkLightingShaderImpl::asFragmentProcessor(GrContext* context, const SkPaint& paint, 
                                                const SkMatrix& viewM, const SkMatrix* localMatrix, 
                                                GrColor* color, GrProcessorDataManager*,
                                                GrFragmentProcessor** fp) const {
     SkDEBUGFAIL("Should not call in GPU-less build");
@@ skipping 32 matching lines @@
     fFlags = flags;
 }
 
 SkLightingShaderImpl::LightingShaderContext::~LightingShaderContext() {
     // The bitmap proc states have been created outside of the context on memory that will be freed
     // elsewhere. Call the destructors but leave the freeing of the memory to the caller.
     fDiffuseState->~SkBitmapProcState();
     fNormalState->~SkBitmapProcState();
 }
 
-static inline int light(SkScalar light, int diff, SkScalar NdotL, SkScalar ambient) {
-    SkScalar color = light * diff * NdotL + 255 * ambient;
-    if (color <= 0.0f) {
-        return 0;
-    } else if (color >= 255.0f) {
-        return 255;
-    } else {
-        return (int) color;
-    }
+static inline SkPMColor convert(SkColor3f color, U8CPU a) {
+    if (color.fX <= 0.0f) {
+        color.fX = 0.0f;
+    } else if (color.fX >= 255.0f) {
+        color.fX = 255.0f;
+    } 
+
+    if (color.fY <= 0.0f) {
+        color.fY = 0.0f;
+    } else if (color.fY >= 255.0f) {
+        color.fY = 255.0f;
+    } 
+
+    if (color.fZ <= 0.0f) {
+        color.fZ = 0.0f;
+    } else if (color.fZ >= 255.0f) {
+        color.fZ = 255.0f;
+    } 
+
+    return SkPreMultiplyARGB(a, (int) color.fX,  (int) color.fY, (int) color.fZ);
 }
 
 // larger is better (fewer times we have to loop), but we shouldn't
-// take up too much stack-space (each could here costs 16 bytes)
+// take up too much stack-space (each one here costs 16 bytes)
 #define TMP_COUNT     16
 
 void SkLightingShaderImpl::LightingShaderContext::shadeSpan(int x, int y,
                                                             SkPMColor result[], int count) {
     const SkLightingShaderImpl& lightShader = static_cast<const SkLightingShaderImpl&>(fShader);
 
-    SkPMColor   tmpColor[TMP_COUNT], tmpColor2[TMP_COUNT];
-    SkPMColor   tmpNormal[TMP_COUNT], tmpNormal2[TMP_COUNT];
+    uint32_t  tmpColor[TMP_COUNT], tmpNormal[TMP_COUNT];
+    SkPMColor tmpColor2[2*TMP_COUNT], tmpNormal2[2*TMP_COUNT];
 
     SkBitmapProcState::MatrixProc   diffMProc = fDiffuseState->getMatrixProc();
     SkBitmapProcState::SampleProc32 diffSProc = fDiffuseState->getSampleProc32();
 
     SkBitmapProcState::MatrixProc   normalMProc = fNormalState->getMatrixProc();
     SkBitmapProcState::SampleProc32 normalSProc = fNormalState->getSampleProc32();
 
+    int diffMax = fDiffuseState->maxCountForBufferSize(sizeof(tmpColor[0]) * TMP_COUNT);
+    int normMax = fNormalState->maxCountForBufferSize(sizeof(tmpNormal[0]) * TMP_COUNT);
+    int max = SkTMin(diffMax, normMax);
+
     SkASSERT(fDiffuseState->fPixmap.addr());
     SkASSERT(fNormalState->fPixmap.addr());
 
-    SkPoint3 norm;
-    SkScalar NdotL;
-    int r, g, b;
+    SkPoint3 norm, xformedNorm;
 
     do {
         int n = count;
-        if (n > TMP_COUNT) {
-            n = TMP_COUNT;
+        if (n > max) {
+            n = max;
         }
 
         diffMProc(*fDiffuseState, tmpColor, n, x, y);
         diffSProc(*fDiffuseState, tmpColor, n, tmpColor2);
 
         normalMProc(*fNormalState, tmpNormal, n, x, y);
         normalSProc(*fNormalState, tmpNormal, n, tmpNormal2);
 
         for (int i = 0; i < n; ++i) {
             SkASSERT(0xFF == SkColorGetA(tmpNormal2[i]));  // opaque -> unpremul
             norm.set(SkIntToScalar(SkGetPackedR32(tmpNormal2[i]))-127.0f,
                      SkIntToScalar(SkGetPackedG32(tmpNormal2[i]))-127.0f,
                      SkIntToScalar(SkGetPackedB32(tmpNormal2[i]))-127.0f);
             norm.normalize();
 
+            xformedNorm.fX = lightShader.fInvNormRotation.fX * norm.fX +
+                             lightShader.fInvNormRotation.fY * norm.fY;
+            xformedNorm.fY = lightShader.fInvNormRotation.fX * norm.fX - 
+                             lightShader.fInvNormRotation.fY * norm.fY;
+            xformedNorm.fZ = norm.fZ;
+
             SkColor diffColor = SkUnPreMultiply::PMColorToColor(tmpColor2[i]);
-            NdotL = norm.dot(lightShader.fLight.fDirection);
 
-            // This is all done in linear unpremul color space
-            r = light(lightShader.fLight.fColor.fX, SkColorGetR(diffColor), NdotL, 
-                      lightShader.fAmbientColor.fX);
-            g = light(lightShader.fLight.fColor.fY, SkColorGetG(diffColor), NdotL, 
-                      lightShader.fAmbientColor.fY);
-            b = light(lightShader.fLight.fColor.fZ, SkColorGetB(diffColor), NdotL, 
-                      lightShader.fAmbientColor.fZ);
+            SkColor3f accum = SkColor3f::Make(0.0f, 0.0f, 0.0f);
+            // This is all done in linear unpremul color space (each component 0..255.0f though)
+            for (int l = 0; l < lightShader.fLights->numLights(); ++l) {
+                const SkLight& light = lightShader.fLights->light(l);
 
-            result[i] = SkPreMultiplyARGB(SkColorGetA(diffColor), r, g, b);
+                if (SkLight::kAmbient_LightType == light.type()) {
+                    accum += light.color().makeScale(255.0f);
+                } else {
+                    SkScalar NdotL = xformedNorm.dot(light.dir());
+                    if (NdotL < 0.0f) {
+                        NdotL = 0.0f;
+                    }
+
+                    accum.fX += light.color().fX * SkColorGetR(diffColor) * NdotL;
+                    accum.fY += light.color().fY * SkColorGetG(diffColor) * NdotL;
+                    accum.fZ += light.color().fZ * SkColorGetB(diffColor) * NdotL;
+                }
+            }
+
+            result[i] = convert(accum, SkColorGetA(diffColor));
         }
 
         result += n;
         x += n;
         count -= n;
     } while (count > 0);
 }
 
 ////////////////////////////////////////////////////////////////////////////
 
 #ifndef SK_IGNORE_TO_STRING
 void SkLightingShaderImpl::toString(SkString* str) const {
     str->appendf("LightingShader: ()");
 }
 #endif
 
 SkFlattenable* SkLightingShaderImpl::CreateProc(SkReadBuffer& buf) {
-    SkMatrix localMatrix;
-    buf.readMatrix(&localMatrix);
+    SkMatrix diffLocalM;
+    bool hasDiffLocalM = buf.readBool();
+    if (hasDiffLocalM) {
+        buf.readMatrix(&diffLocalM);
+    } else {
+        diffLocalM.reset();
+    }
+
+    SkMatrix normLocalM;
+    bool hasNormLocalM = buf.readBool();
+    if (hasNormLocalM) {
+        buf.readMatrix(&normLocalM);
+    } else {
+        normLocalM.reset();
+    }
 
     SkBitmap diffuse;
     if (!buf.readBitmap(&diffuse)) {
         return NULL;
     }
     diffuse.setImmutable();
 
     SkBitmap normal;
     if (!buf.readBitmap(&normal)) {
         return NULL;
     }
     normal.setImmutable();
 
-    SkLightingShader::Light light;
-    if (!buf.readScalarArray(&light.fDirection.fX, 3)) {
-        return NULL;
-    }
-    if (!buf.readScalarArray(&light.fColor.fX, 3)) {
-        return NULL;
+    int numLights = buf.readInt();
+
+    SkLightingShader::Lights::Builder builder;
+
+    for (int l = 0; l < numLights; ++l) {
+        bool isAmbient = buf.readBool();
+
+        SkColor3f color;
+        if (!buf.readScalarArray(&color.fX, 3)) {
+            return NULL;
+        }
+
+        if (isAmbient) {
+            builder.add(SkLight::SkLight(color));
+        } else {
+            SkVector3 dir;
+            if (!buf.readScalarArray(&dir.fX, 3)) {
+                return NULL;
+            }
+            builder.add(SkLight::SkLight(color, dir));        
+        }
     }
 
-    SkColor3f ambient;
-    if (!buf.readScalarArray(&ambient.fX, 3)) {
-        return NULL;
-    }
+    SkAutoTUnref<const SkLightingShader::Lights> lights(builder.finish());
 
-    return SkNEW_ARGS(SkLightingShaderImpl, (diffuse, normal, light, ambient, &localMatrix));
+    return SkNEW_ARGS(SkLightingShaderImpl, (diffuse, normal, lights,
+                                             SkVector::Make(1.0f, 0.0f),
+                                             &diffLocalM, &normLocalM));
 }
 
 void SkLightingShaderImpl::flatten(SkWriteBuffer& buf) const {
-    buf.writeMatrix(this->getLocalMatrix());
+    this->INHERITED::flatten(buf);
+
+    bool hasNormLocalM = !fNormLocalMatrix.isIdentity();
+    buf.writeBool(hasNormLocalM);
+    if (hasNormLocalM) {
+        buf.writeMatrix(fNormLocalMatrix);
+    }
 
     buf.writeBitmap(fDiffuseMap);
     buf.writeBitmap(fNormalMap);
-    buf.writeScalarArray(&fLight.fDirection.fX, 3);
-    buf.writeScalarArray(&fLight.fColor.fX, 3);
-    buf.writeScalarArray(&fAmbientColor.fX, 3);
+
+    buf.writeInt(fLights->numLights());
+    for (int l = 0; l < fLights->numLights(); ++l) {
+        const SkLight& light = fLights->light(l);
+
+        bool isAmbient = SkLight::kAmbient_LightType == light.type();
+
+        buf.writeBool(isAmbient);
+        buf.writeScalarArray(&light.color().fX, 3);
+        if (!isAmbient) {
+            buf.writeScalarArray(&light.dir().fX, 3);
+        }
+    }
+}
+
+bool SkLightingShaderImpl::computeNormTotalInverse(const ContextRec& rec,
+                                                   SkMatrix* normTotalInverse) const {
+    SkMatrix total;
+    total.setConcat(*rec.fMatrix, fNormLocalMatrix);
+
+    const SkMatrix* m = &total;
+    if (rec.fLocalMatrix) {
+        total.setConcat(*m, *rec.fLocalMatrix);
+        m = &total;
+    }
+    return m->invert(normTotalInverse);
 }
 
 SkShader::Context* SkLightingShaderImpl::onCreateContext(const ContextRec& rec,
                                                          void* storage) const {
 
-    SkMatrix totalInverse;
-    // Do this first, so we know the matrix can be inverted.
-    if (!this->computeTotalInverse(rec, &totalInverse)) {
+    SkMatrix diffTotalInv;
+    // computeTotalInverse was called in SkShader::createContext so we know it will succeed
+    SkAssertResult(this->computeTotalInverse(rec, &diffTotalInv));
+
+    SkMatrix normTotalInv;
+    if (!this->computeNormTotalInverse(rec, &normTotalInv)) {
         return NULL;
     }
 
     void* diffuseStateStorage = (char*)storage + sizeof(LightingShaderContext);
     SkBitmapProcState* diffuseState = SkNEW_PLACEMENT(diffuseStateStorage, SkBitmapProcState);
     SkASSERT(diffuseState);
 
     diffuseState->fTileModeX = SkShader::kClamp_TileMode;
     diffuseState->fTileModeY = SkShader::kClamp_TileMode;
     diffuseState->fOrigBitmap = fDiffuseMap;
-    if (!diffuseState->chooseProcs(totalInverse, *rec.fPaint)) {
+    if (!diffuseState->chooseProcs(diffTotalInv, *rec.fPaint)) {
         diffuseState->~SkBitmapProcState();
         return NULL;
     }
 
     void* normalStateStorage = (char*)storage + sizeof(LightingShaderContext) + sizeof(SkBitmapProcState);
     SkBitmapProcState* normalState = SkNEW_PLACEMENT(normalStateStorage, SkBitmapProcState);
     SkASSERT(normalState);
 
     normalState->fTileModeX = SkShader::kClamp_TileMode;
     normalState->fTileModeY = SkShader::kClamp_TileMode;
     normalState->fOrigBitmap = fNormalMap;
-    if (!normalState->chooseProcs(totalInverse, *rec.fPaint)) {
+    if (!normalState->chooseProcs(normTotalInv, *rec.fPaint)) {
         diffuseState->~SkBitmapProcState();
         normalState->~SkBitmapProcState();
         return NULL;
     }
 
     return SkNEW_PLACEMENT_ARGS(storage, LightingShaderContext, (*this, rec,
                                                                  diffuseState, normalState));
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 static bool bitmap_is_too_big(const SkBitmap& bm) {
     // SkBitmapProcShader stores bitmap coordinates in a 16bit buffer, as it
     // communicates between its matrix-proc and its sampler-proc. Until we can
     // widen that, we have to reject bitmaps that are larger.
     //
     static const int kMaxSize = 65535;
 
     return bm.width() > kMaxSize || bm.height() > kMaxSize;
 }
 
 SkShader* SkLightingShader::Create(const SkBitmap& diffuse, const SkBitmap& normal,
-                                   const SkLightingShader::Light& light,
-                                   const SkColor3f& ambient,
-                                   const SkMatrix* localMatrix) {
+                                   const Lights* lights,
+                                   const SkVector& invNormRotation,
+                                   const SkMatrix* diffLocalM, const SkMatrix* normLocalM) {
     if (diffuse.isNull() || bitmap_is_too_big(diffuse) ||
         normal.isNull() || bitmap_is_too_big(normal) ||
         diffuse.width() != normal.width() ||
         diffuse.height() != normal.height()) {
         return nullptr;
     }
 
-    return SkNEW_ARGS(SkLightingShaderImpl, (diffuse, normal, light, ambient, localMatrix));
+    SkASSERT(SkScalarNearlyEqual(invNormRotation.lengthSqd(), SK_Scalar1));
+
+    return SkNEW_ARGS(SkLightingShaderImpl, (diffuse, normal, lights,
+                                             invNormRotation, diffLocalM, normLocalM));
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkLightingShader)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkLightingShaderImpl)
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END
 
 ///////////////////////////////////////////////////////////////////////////////