added in radial shadows

src/core/Sk2DShadowMapShader.cpp

Index: src/core/Sk2DShadowMapShader.cpp
diff --git a/src/core/Sk2DShadowMapShader.cpp b/src/core/Sk2DShadowMapShader.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..5af7761702650d713c20ed75d127750f9a230fd5
--- /dev/null
+++ b/src/core/Sk2DShadowMapShader.cpp
@@ -0,0 +1,424 @@
+/*
+ * 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 "Sk2DShadowMapShader.h"
+#include "SkLights.h"
+#include "SkPoint3.h"
+#include "SkReadBuffer.h"
+#include "SkShadowShader.h"
+
+////////////////////////////////////////////////////////////////////////////
+#ifdef SK_EXPERIMENTAL_SHADOWING
+
+
+/** \class Sk2DShadowMapShaderImpl
+    This subclass of shader applies shadowing

[jvanverth1, 2016/09/07 14:47:23]

Needs a little more detail here. "... shadowing radially around a light"?

[vjiaoblack, 2016/09/07 15:21:39]

Done.

+*/
+class Sk2DShadowMapShaderImpl : public SkShader {
+public:
+    /** Create a new shadowing shader that shadows

[jvanverth1, 2016/09/07 14:47:23]

"... shadows radially around a light"?

[vjiaoblack, 2016/09/07 15:21:39]

Done.

+    */
+    Sk2DShadowMapShaderImpl(sk_sp<SkShader> occluderShader,
+                       sk_sp<SkLights> lights,

[jvanverth1, 2016/09/07 14:47:23]

Nit: indent to (

[vjiaoblack, 2016/09/07 15:21:39]

Done.

+                       int diffuseWidth, int diffuseHeight)
+            : fOccluderShader(std::move(occluderShader))

[jvanverth1, 2016/09/07 14:47:23]

Nit: indent 4 spaces

[vjiaoblack, 2016/09/07 15:21:39]

Done.

+            , fLight(std::move(lights))
+            , fWidth(diffuseWidth)
+            , fHeight(diffuseHeight) { }
+
+    bool isOpaque() const override;
+
+#if SK_SUPPORT_GPU
+    sk_sp<GrFragmentProcessor> asFragmentProcessor(const AsFPArgs&) const override;
+#endif
+
+    class ShadowMap2DShaderContext : public SkShader::Context {
+    public:
+        // The context takes ownership of the states. It will call their destructors
+        // but will NOT free the memory.
+        ShadowMap2DShaderContext(const Sk2DShadowMapShaderImpl&, const ContextRec&,
+                            SkShader::Context* occluderContext,

[jvanverth1, 2016/09/07 14:47:22]

Nit: indent to (

[vjiaoblack, 2016/09/07 15:21:39]

Done.

+                            void* heapAllocated);
+
+        ~ShadowMap2DShaderContext() override;
+
+        void shadeSpan(int x, int y, SkPMColor[], int count) override;
+
+        uint32_t getFlags() const override { return fFlags; }
+
+    private:
+        SkShader::Context*        fOccluderContext;
+        uint32_t                  fFlags;
+
+        void* fHeapAllocated;
+
+        typedef SkShader::Context INHERITED;
+    };
+
+    SK_TO_STRING_OVERRIDE()
+SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(Sk2DShadowMapShaderImpl)

[jvanverth1, 2016/09/07 14:47:23]

Indent

[vjiaoblack, 2016/09/07 15:21:39]

Done.

+
+protected:
+    void flatten(SkWriteBuffer&) const override;
+    size_t onContextSize(const ContextRec&) const override;
+    Context* onCreateContext(const ContextRec&, void*) const override;
+
+private:
+    sk_sp<SkShader> fOccluderShader;
+    sk_sp<SkLights> fLight;
+
+    int fWidth;
+    int fHeight;
+
+    friend class Sk2DShadowMapShader;
+
+    typedef SkShader INHERITED;
+};
+
+////////////////////////////////////////////////////////////////////////////
+
+#if SK_SUPPORT_GPU
+
+#include "GrContext.h"
+#include "GrCoordTransform.h"
+#include "GrFragmentProcessor.h"
+#include "glsl/GrGLSLFragmentProcessor.h"
+#include "glsl/GrGLSLFragmentShaderBuilder.h"
+#include "SkGr.h"
+#include "SkGrPriv.h"
+#include "SkImage_Base.h"
+#include "GrInvariantOutput.h"
+#include "SkSpecialImage.h"
+
+class TwoDShadowMapFP : public GrFragmentProcessor {

[jvanverth1, 2016/09/07 14:47:23]

RadialShadowMapFP?

[vjiaoblack, 2016/09/07 15:21:39]

Done.

+public:
+    TwoDShadowMapFP(sk_sp<GrFragmentProcessor> occluder,
+             sk_sp<SkLights> light,

[jvanverth1, 2016/09/07 14:47:23]

Indent to (

[vjiaoblack, 2016/09/07 15:21:39]

Done.

+             int diffuseWidth, int diffuseHeight,
+             GrContext* context) {
+        fLightDir = light->light(0).pos();
+
+        fWidth = diffuseWidth;
+        fHeight = diffuseHeight;
+
+        this->registerChildProcessor(std::move(occluder));
+        this->initClassID<TwoDShadowMapFP>();
+    }
+
+    class GLSLTwoDShadowMapFP : public GrGLSLFragmentProcessor {
+    public:
+        GLSLTwoDShadowMapFP() { }
+
+        void emitCode(EmitArgs& args) override {
+
+            GrGLSLFragmentBuilder* fragBuilder = args.fFragBuilder;
+            GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
+
+            const char* lightDirUniName = nullptr;

[jvanverth1, 2016/09/07 14:47:23]

lightPosUniName?

[vjiaoblack, 2016/09/07 15:21:39]

Done.

+
+            fLightDirUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
+                                                      kVec3f_GrSLType,
+                                                      kDefault_GrSLPrecision,
+                                                      "lightDir",
+                                                      &lightDirUniName);
+
+            const char* widthUniName = nullptr;
+            const char* heightUniName = nullptr;
+
+            fWidthUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
+                                                   kInt_GrSLType,
+                                                   kDefault_GrSLPrecision,
+                                                   "width", &widthUniName);
+            fHeightUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
+                                                    kInt_GrSLType,
+                                                    kDefault_GrSLPrecision,
+                                                    "height", &heightUniName);
+
+
+            SkString occluder("occluder");
+            this->emitChild(0, nullptr, &occluder, args);
+
+            // the above isn't good enough. We need to modify the indexing coordinate.

[jvanverth1, 2016/09/07 14:47:22]

Is this a TODO? Or do you plan to do it in this change?

[vjiaoblack, 2016/09/07 15:21:39]

It's an explanation of what the code below does

+
+            fragBuilder->codeAppendf("float distHere;");
+            fragBuilder->codeAppendf("float closestDistHere = 0;");
+            fragBuilder->codeAppendf("vec2 coords = vMatrixCoord_0_0_Stage0;");
+            fragBuilder->codeAppendf("coords.y = 0;");
+            fragBuilder->codeAppendf("vec2 destCoords = vec2(0,0);");
+            fragBuilder->codeAppendf("float step = 0.0025;");

[jvanverth1, 2016/09/07 14:47:24]

Is there an assumption of texture size here? Should step be 1/fHeightUni?

[vjiaoblack, 2016/09/07 15:21:39]

Done.

+
+            // assume that we are at 0, 0 light pos
+            // TODO use correct light positions

[jvanverth1, 2016/09/07 14:47:23]

Could use a comment explaining what this loop is doing and what the structure of
the texture is.

[vjiaoblack, 2016/09/07 15:21:39]

Done.

+            fragBuilder->codeAppendf("for (coords.y = 0; coords.y <= 1; coords.y += step) {");
+
+                fragBuilder->codeAppendf("vec2 norm = coords * 2.0 - 1.0;");
+                fragBuilder->codeAppendf("float theta = 3.1415 * 1.5 + norm.x * 3.1415;");

[jvanverth1, 2016/09/07 14:47:23]

It looks like this will vary from pi/2 to 5*pi/2. Is that right?

[vjiaoblack, 2016/09/07 15:21:39]

 Tis right for now. (The light is fixed)

+                fragBuilder->codeAppendf("float r = (1.0 + norm.y) * 0.5;");

[jvanverth1, 2016/09/07 14:47:23]

I think this is just coords.y again.

+                fragBuilder->codeAppendf("destCoords = "
+                        "vec2(-r * sin(theta), -r * cos(theta)) /2.0 + 0.5;");

[jvanverth1, 2016/09/07 14:47:23]

The -r is odd to me -- negative polar coords? And I don't think this will
compile: you're adding a float (0.5) to a vec2.

[vjiaoblack, 2016/09/07 15:21:39]

That compiles to + vec(0.5, 0.5)

+                fragBuilder->codeAppendf("distHere = texture(uTextureSampler0_Stage1, "
+                                                            "destCoords).b;");
+                fragBuilder->codeAppendf("if (distHere > 0.0) {"
+                                         "closestDistHere = 1-coords.y;"
+                                         "break;}");
+            fragBuilder->codeAppendf("}");
+
+            fragBuilder->codeAppendf("%s = vec4(vec3(closestDistHere),1);", args.fOutputColor);
+        }
+
+        static void GenKey(const GrProcessor& proc, const GrGLSLCaps&,
+                           GrProcessorKeyBuilder* b) {
+            b->add32(0); // nothing to add here
+        }
+
+    protected:
+        void onSetData(const GrGLSLProgramDataManager& pdman, const GrProcessor& proc) override {
+            const TwoDShadowMapFP &twoDShadowMapFP = proc.cast<TwoDShadowMapFP>();
+
+            const SkVector3& lightDir = twoDShadowMapFP.lightDir();
+            if (lightDir != fLightDir) {
+                pdman.set3fv(fLightDirUni, 1, &lightDir.fX);
+                fLightDir = lightDir;
+            }
+
+            int width = twoDShadowMapFP.width();
+            if (width != fWidth) {
+                pdman.set1i(fWidthUni, width);
+                fWidth = width;
+            }
+            int height = twoDShadowMapFP.height();
+            if (height != fHeight) {
+                pdman.set1i(fHeightUni, height);
+                fHeight = height;
+            }
+        }
+
+    private:
+        SkVector3 fLightDir;
+        GrGLSLProgramDataManager::UniformHandle fLightDirUni;
+
+        int fWidth;
+        GrGLSLProgramDataManager::UniformHandle fWidthUni;
+        int fHeight;
+        GrGLSLProgramDataManager::UniformHandle fHeightUni;
+    };
+
+    void onGetGLSLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override {
+        GLSLTwoDShadowMapFP::GenKey(*this, caps, b);
+    }
+
+    const char* name() const override { return "twoDShadowMapFP"; }

[jvanverth1, 2016/09/07 14:47:23]

"radialShadowMapFP"

[vjiaoblack, 2016/09/07 15:21:39]

Done.

+
+    void onComputeInvariantOutput(GrInvariantOutput* inout) const override {
+        inout->mulByUnknownFourComponents();
+    }
+    const SkVector3& lightDir() const {
+        return fLightDir;
+    }
+
+    int width() const {return fWidth; }
+    int height() const {return fHeight; }
+
+private:
+    GrGLSLFragmentProcessor* onCreateGLSLInstance() const override {
+        return new GLSLTwoDShadowMapFP;
+    }
+
+    bool onIsEqual(const GrFragmentProcessor& proc) const override {
+        const TwoDShadowMapFP& twoDShadowMapFP = proc.cast<TwoDShadowMapFP>();
+
+        if (fWidth != twoDShadowMapFP.fWidth || fHeight != twoDShadowMapFP.fHeight) {
+            return false;
+        }
+
+        if (fLightDir != twoDShadowMapFP.fLightDir) {
+            return false;
+        }
+
+        return true;
+    }
+
+    SkVector3        fLightDir;

[jvanverth1, 2016/09/07 14:47:23]

There's no direction in this case, so fLightPos?

[vjiaoblack, 2016/09/07 15:21:39]

Done.

+
+    int              fHeight;
+    int              fWidth;
+};
+
+////////////////////////////////////////////////////////////////////////////
+
+sk_sp<GrFragmentProcessor> Sk2DShadowMapShaderImpl::asFragmentProcessor(const AsFPArgs& fpargs)
+        const {
+
+    sk_sp<GrFragmentProcessor> occluderFP = fOccluderShader->asFragmentProcessor(fpargs);
+
+    sk_sp<GrFragmentProcessor> shadowfp = sk_make_sp<TwoDShadowMapFP>(std::move(occluderFP),
+                                                               std::move(fLight),
+                                                               fWidth, fHeight,
+                                                               fpargs.fContext);
+    return shadowfp;
+}
+
+#endif
+
+////////////////////////////////////////////////////////////////////////////
+
+bool Sk2DShadowMapShaderImpl::isOpaque() const {
+    return fOccluderShader->isOpaque();
+}
+
+Sk2DShadowMapShaderImpl::ShadowMap2DShaderContext::ShadowMap2DShaderContext(

[jvanverth1, 2016/09/07 14:47:23]

SkRadialShadowMapShaderImpl

[vjiaoblack, 2016/09/07 15:21:39]

Done.

+        const Sk2DShadowMapShaderImpl& shader, const ContextRec& rec,
+        SkShader::Context* occluderContext,
+        void* heapAllocated)
+        : INHERITED(shader, rec)
+        , fOccluderContext(occluderContext)
+        , fHeapAllocated(heapAllocated) {
+    bool isOpaque = shader.isOpaque();
+
+    // update fFlags
+    uint32_t flags = 0;
+    if (isOpaque && (255 == this->getPaintAlpha())) {
+        flags |= kOpaqueAlpha_Flag;
+    }
+
+    fFlags = flags;
+}
+
+Sk2DShadowMapShaderImpl::ShadowMap2DShaderContext::~ShadowMap2DShaderContext() {
+    // The dependencies have been created outside of the context on memory that was allocated by
+    // the onCreateContext() method. Call the destructors and free the memory.
+    fOccluderContext->~Context();
+
+    sk_free(fHeapAllocated);
+}
+
+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 one here costs 16 bytes)
+#define BUFFER_MAX 16
+void Sk2DShadowMapShaderImpl::ShadowMap2DShaderContext::shadeSpan(int x, int y,
+                                                        SkPMColor result[], int count) {
+    do {
+        int n = SkTMin(count, BUFFER_MAX);
+
+        for (int i = 0; i < n; ++i) {

[jvanverth1, 2016/09/07 14:47:23]

// Fill with white for now

[vjiaoblack, 2016/09/07 15:21:39]

Done.

+            SkColor3f accum = SkColor3f::Make(1.0f, 1.0f, 1.0f);

[jvanverth1, 2016/09/07 14:47:23]

This and the convert() could be outside the loop.

[vjiaoblack, 2016/09/07 15:21:39]

Done.

+            result[i] = convert(accum, 0xFF);
+        }
+
+        result += n;
+        x += n;
+        count -= n;
+    } while (count > 0);
+}
+
+////////////////////////////////////////////////////////////////////////////
+
+#ifndef SK_IGNORE_TO_STRING
+void Sk2DShadowMapShaderImpl::toString(SkString* str) const {
+    str->appendf("2DShadowMapShader: ()");
+}
+#endif
+
+sk_sp<SkFlattenable> Sk2DShadowMapShaderImpl::CreateProc(SkReadBuffer& buf) {
+
+    // Discarding SkShader flattenable params
+    bool hasLocalMatrix = buf.readBool();
+    SkAssertResult(!hasLocalMatrix);
+
+    sk_sp<SkLights> light = SkLights::MakeFromBuffer(buf);
+
+    int diffuseWidth = buf.readInt();
+    int diffuseHeight = buf.readInt();
+
+    sk_sp<SkShader> occluderShader(buf.readFlattenable<SkShader>());
+
+    return sk_make_sp<Sk2DShadowMapShaderImpl>(std::move(occluderShader),
+                                               std::move(light),
+                                               diffuseWidth, diffuseHeight);
+}
+
+void Sk2DShadowMapShaderImpl::flatten(SkWriteBuffer& buf) const {
+    this->INHERITED::flatten(buf);
+
+    fLight->flatten(buf);
+
+    buf.writeInt(fWidth);
+    buf.writeInt(fHeight);
+
+    buf.writeFlattenable(fOccluderShader.get());
+}
+
+size_t Sk2DShadowMapShaderImpl::onContextSize(const ContextRec& rec) const {
+    return sizeof(ShadowMap2DShaderContext);
+}
+
+SkShader::Context* Sk2DShadowMapShaderImpl::onCreateContext(const ContextRec& rec,
+                                                       void* storage) const {
+    size_t heapRequired = fOccluderShader->contextSize(rec);
+
+    void* heapAllocated = sk_malloc_throw(heapRequired);
+
+    void* occluderContextStorage = heapAllocated;
+
+    SkShader::Context* occluderContext =
+            fOccluderShader->createContext(rec, occluderContextStorage);
+
+    if (!occluderContext) {
+        sk_free(heapAllocated);
+        return nullptr;
+    }
+
+    return new (storage) ShadowMap2DShaderContext(*this, rec, occluderContext, heapAllocated);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+sk_sp<SkShader> Sk2DShadowMapShader::Make(sk_sp<SkShader> occluderShader,
+                                          sk_sp<SkLights> light,
+                                          int diffuseWidth, int diffuseHeight) {
+    if (!occluderShader) {
+        // TODO: Use paint's color in absence of a diffuseShader
+        // TODO: Use a default implementation of normalSource instead
+        return nullptr;
+    }
+
+    return sk_make_sp<Sk2DShadowMapShaderImpl>(std::move(occluderShader),
+                                               std::move(light),
+                                               diffuseWidth, diffuseHeight);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(Sk2DShadowMapShader)
+    SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(Sk2DShadowMapShaderImpl)

[jvanverth1, 2016/09/07 14:47:23]

Indent

[vjiaoblack, 2016/09/07 15:21:39]

Done.

+SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END
+
+///////////////////////////////////////////////////////////////////////////////
+
+#endif