Refactoring of GPU NormalMap handling out into its own class

src/core/SkLightingShader_NormalSource.cpp

Index: src/core/SkLightingShader_NormalSource.cpp
diff --git a/src/core/SkLightingShader_NormalSource.cpp b/src/core/SkLightingShader_NormalSource.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..b96b1bf083c314b4f6e33f94bb21b5c0c5c0fb59
--- /dev/null
+++ b/src/core/SkLightingShader_NormalSource.cpp
@@ -0,0 +1,290 @@
+/*
+ * 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 "SkBitmapProcShader.h"
+#include "SkError.h"
+#include "SkErrorInternals.h"
+#include "SkLightingShader.h"
+#include "SkReadBuffer.h"
+#include "SkWriteBuffer.h"
+
+// Genretating vtable
+SkLightingShader::NormalSource::~NormalSource() {}
+
+///////////////////////////////////////////////////////////////////////////////
+
+class NormalMapSourceImpl : public SkLightingShader::NormalSource {
+public:
+    NormalMapSourceImpl(const SkBitmap &normal, const SkVector &invNormRotation,
+                        const SkMatrix *normLocalM)
+        : fNormalMap(normal)
+        , fInvNormRotation(invNormRotation) {
+
+        if (normLocalM) {
+            fNormLocalMatrix = *normLocalM;
+        } else {
+            fNormLocalMatrix.reset();
+        }
+        // Pre-cache so future calls to fNormLocalMatrix.getType() are threadsafe.
+        (void)fNormLocalMatrix.getType();
+    }
+
+#if SK_SUPPORT_GPU
+    sk_sp<GrFragmentProcessor> asFragmentProcessor(GrContext*,
+                                                   const SkMatrix& viewM,
+                                                   const SkMatrix* localMatrix,
+                                                   SkFilterQuality,
+                                                   SkSourceGammaTreatment) const override;
+#endif
+
+    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(NormalMapSourceImpl)
+
+protected:
+    void flatten(SkWriteBuffer& buf) const override;
+
+private:
+    SkBitmap        fNormalMap;
+    SkMatrix        fNormLocalMatrix;
+    SkVector        fInvNormRotation;
+
+    friend class SkLightingShader::NormalSource;
+
+    typedef SkLightingShader::NormalSource INHERITED;
+};
+
+////////////////////////////////////////////////////////////////////////////
+
+#if SK_SUPPORT_GPU
+
+#include "GrCoordTransform.h"
+#include "GrInvariantOutput.h"
+#include "GrTextureParams.h"
+#include "glsl/GrGLSLFragmentProcessor.h"
+#include "glsl/GrGLSLFragmentShaderBuilder.h"
+#include "SkGr.h"
+
+class NormalMapFP : public GrFragmentProcessor {
+public:
+    NormalMapFP(GrTexture* normal, const SkMatrix& normMatrix, const GrTextureParams& normParams,
+                const SkVector& invNormRotation)
+        : fNormDeviceTransform(kLocal_GrCoordSet, normMatrix, normal, normParams.filterMode())
+        , fNormalTextureAccess(normal, normParams)
+        , fInvNormRotation(invNormRotation) {
+        this->addCoordTransform(&fNormDeviceTransform);
+        this->addTextureAccess(&fNormalTextureAccess);
+
+        this->initClassID<NormalMapFP>();
+    }
+
+    class GLSLNormalMapFP : public GrGLSLFragmentProcessor {
+    public:
+        GLSLNormalMapFP() {
+            fInvNormRotation.set(0.0f, 0.0f);
+        }
+
+        void emitCode(EmitArgs& args) override {
+
+            GrGLSLFragmentBuilder* fragBuilder = args.fFragBuilder;
+            GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
+
+            // add uniform
+            const char* xformUniName = nullptr;
+            fXformUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
+                                                   kVec2f_GrSLType, kDefault_GrSLPrecision,
+                                                   "Xform", &xformUniName);
+
+            fragBuilder->codeAppend("vec4 normalColor = ");
+            fragBuilder->appendTextureLookup(args.fTexSamplers[0],
+                                             args.fCoords[0].c_str(),
+                                             args.fCoords[0].getType());
+            fragBuilder->codeAppend(";");
+
+            fragBuilder->codeAppend("vec3 normal = normalColor.rgb - vec3(0.5);");
+
+            // TODO: inverse map the light direction vectors in the vertex shader rather than
+            // transforming all the normals here!
+            fragBuilder->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);
+
+            fragBuilder->codeAppend("normal = normalize(m*normal);");
+            fragBuilder->codeAppendf("%s = vec4(normal, 0);", args.fOutputColor);
+        }
+
+        static void GenKey(const GrProcessor& proc, const GrGLSLCaps&,
+                           GrProcessorKeyBuilder* b) {
+            b->add32(0x0);
+        }
+
+    protected:
+        void onSetData(const GrGLSLProgramDataManager& pdman, const GrProcessor& proc) override {
+            const NormalMapFP& normalMapFP = proc.cast<NormalMapFP>();
+
+            const SkVector& invNormRotation = normalMapFP.invNormRotation();
+            if (invNormRotation != fInvNormRotation) {
+                pdman.set2fv(fXformUni, 1, &invNormRotation.fX);
+                fInvNormRotation = invNormRotation;
+            }
+        }
+
+    private:
+        SkVector fInvNormRotation;
+        GrGLSLProgramDataManager::UniformHandle fXformUni;
+    };
+
+    void onGetGLSLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override {
+        GLSLNormalMapFP::GenKey(*this, caps, b);
+    }
+
+    const char* name() const override { return "NormalMapFP"; }
+
+    void onComputeInvariantOutput(GrInvariantOutput* inout) const override {
+        inout->setToUnknown(GrInvariantOutput::ReadInput::kWillNot_ReadInput);
+    }
+
+    const SkVector& invNormRotation() const { return fInvNormRotation; }
+
+private:
+    GrGLSLFragmentProcessor* onCreateGLSLInstance() const override { return new GLSLNormalMapFP; }
+
+    bool onIsEqual(const GrFragmentProcessor& proc) const override {
+        const NormalMapFP& normalMapFP = proc.cast<NormalMapFP>();
+        return fNormDeviceTransform == normalMapFP.fNormDeviceTransform &&
+               fNormalTextureAccess == normalMapFP.fNormalTextureAccess &&
+               fInvNormRotation     == normalMapFP.fInvNormRotation;
+    }
+
+    GrCoordTransform fNormDeviceTransform;
+    GrTextureAccess  fNormalTextureAccess;
+    SkVector         fInvNormRotation;
+};
+
+// TODO same code at SkLightingShader.cpp. Refactor to common source!
+static bool make_mat(const SkBitmap& bm,
+                     const SkMatrix& localMatrix1,
+                     const SkMatrix* localMatrix2,
+                     SkMatrix* result) {
+
+    result->setIDiv(bm.width(), bm.height());
+
+    SkMatrix lmInverse;
+    if (!localMatrix1.invert(&lmInverse)) {
+        return false;
+    }
+    if (localMatrix2) {
+        SkMatrix inv;
+        if (!localMatrix2->invert(&inv)) {
+            return false;
+        }
+        lmInverse.postConcat(inv);
+    }
+    result->preConcat(lmInverse);
+
+    return true;
+}
+
+sk_sp<GrFragmentProcessor> NormalMapSourceImpl::asFragmentProcessor(
+                                                     GrContext *context,
+                                                     const SkMatrix &viewM,
+                                                     const SkMatrix *localMatrix,
+                                                     SkFilterQuality filterQuality,
+                                                     SkSourceGammaTreatment gammaTreatment) const {
+
+    // TODO Here, the old code was checking that diffuse map and normal map are same size, that
+    //      will be addressed when diffuse maps are factored out of SkLightingShader in a future CL
+
+    SkMatrix normM;
+    if (!make_mat(fNormalMap, fNormLocalMatrix, localMatrix, &normM)) {
+        return nullptr;
+    }
+
+    bool doBicubic;
+    GrTextureParams::FilterMode normFilterMode = GrSkFilterQualityToGrFilterMode(
+            SkTMin(filterQuality, kMedium_SkFilterQuality),
+            viewM,
+            fNormLocalMatrix,
+            &doBicubic);
+    SkASSERT(!doBicubic);
+
+    // TODO: support other tile modes
+    GrTextureParams normParams(SkShader::kClamp_TileMode, normFilterMode);
+    SkAutoTUnref<GrTexture> normalTexture(GrRefCachedBitmapTexture(context,
+                                                                   fNormalMap,
+                                                                   normParams,
+                                                                   gammaTreatment));
+    if (!normalTexture) {
+        SkErrorInternals::SetError(kInternalError_SkError, "Couldn't convert bitmap to texture.");
+        return nullptr;
+    }
+
+    return sk_make_sp<NormalMapFP>(normalTexture, normM, normParams, fInvNormRotation);
+}
+
+#endif // SK_SUPPORT_GPU
+
+////////////////////////////////////////////////////////////////////////////
+
+sk_sp<SkFlattenable> NormalMapSourceImpl::CreateProc(SkReadBuffer& buf) {
+
+    SkMatrix normLocalM;
+    bool hasNormLocalM = buf.readBool();
+    if (hasNormLocalM) {
+        buf.readMatrix(&normLocalM);
+    } else {
+        normLocalM.reset();
+    }
+
+    SkBitmap normal;
+    if (!buf.readBitmap(&normal)) {
+        return nullptr;
+    }
+    normal.setImmutable();
+
+    SkVector invNormRotation = {1,0};
+    if (!buf.isVersionLT(SkReadBuffer::kLightingShaderWritesInvNormRotation)) {
+        invNormRotation = buf.readPoint();
+    }
+
+    return sk_make_sp<NormalMapSourceImpl>(normal, invNormRotation, &normLocalM);
+}
+
+void NormalMapSourceImpl::flatten(SkWriteBuffer& buf) const {
+    this->INHERITED::flatten(buf);
+
+    bool hasNormLocalM = !fNormLocalMatrix.isIdentity();
+    buf.writeBool(hasNormLocalM);
+    if (hasNormLocalM) {
+        buf.writeMatrix(fNormLocalMatrix);
+    }
+
+    buf.writeBitmap(fNormalMap);
+    buf.writePoint(fInvNormRotation);
+}
+
+////////////////////////////////////////////////////////////////////////////
+
+sk_sp<SkLightingShader::NormalSource> SkLightingShader::NormalSource::MakeMap(
+        const SkBitmap &normal, const SkVector &invNormRotation, const SkMatrix *normLocalM) {
+
+    // TODO not checking normal and diffuse maps to be same size, will be addressed when diffuse
+    //      maps are factored out of SkLightingShader in a future CL
+    if (normal.isNull() || SkBitmapProcShader::BitmapIsTooBig(normal)) {
+        return nullptr;
+    }
+
+    SkASSERT(SkScalarNearlyEqual(invNormRotation.lengthSqd(), SK_Scalar1));
+
+    return sk_make_sp<NormalMapSourceImpl>(normal, invNormRotation, normLocalM);
+}
+
+////////////////////////////////////////////////////////////////////////////
+
+SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkLightingShader::NormalSource)
+    SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(NormalMapSourceImpl)
+SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END
+
+////////////////////////////////////////////////////////////////////////////