added in radial shadows

src/core/SkRadialShadowMapShader.cpp

Index: src/core/SkRadialShadowMapShader.cpp
diff --git a/src/core/SkRadialShadowMapShader.cpp b/src/core/SkRadialShadowMapShader.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..24b54a5e2be3a1f2271c194b7e2dddbf076e1ff7
--- /dev/null
+++ b/src/core/SkRadialShadowMapShader.cpp
@@ -0,0 +1,429 @@
+/*
+ * 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 "SkLights.h"
+#include "SkPoint3.h"
+#include "SkRadialShadowMapShader.h"
+
+////////////////////////////////////////////////////////////////////////////
+#ifdef SK_EXPERIMENTAL_SHADOWING
+
+
+/** \class SkRadialShadowMapShaderImpl
+    This subclass of shader applies shadowing radially around a light
+*/
+class SkRadialShadowMapShaderImpl : public SkShader {
+public:
+    /** Create a new shadowing shader that shadows radially around a light
+    */
+    SkRadialShadowMapShaderImpl(sk_sp<SkShader> occluderShader,
+                                sk_sp<SkLights> lights,
+                                int diffuseWidth, int diffuseHeight)
+        : fOccluderShader(std::move(occluderShader))
+        , 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 ShadowMapRadialShaderContext : public SkShader::Context {
+    public:
+        // The context takes ownership of the states. It will call their destructors
+        // but will NOT free the memory.
+        ShadowMapRadialShaderContext(const SkRadialShadowMapShaderImpl&, const ContextRec&,
+                                 SkShader::Context* occluderContext,
+                                 void* heapAllocated);
+
+        ~ShadowMapRadialShaderContext() 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(SkRadialShadowMapShaderImpl)
+
+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 SkRadialShadowMapShader;
+
+    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 RadialShadowMapFP : public GrFragmentProcessor {
+public:
+    RadialShadowMapFP(sk_sp<GrFragmentProcessor> occluder,
+                      sk_sp<SkLights> light,
+                      int diffuseWidth, int diffuseHeight,
+                      GrContext* context) {
+        fLightPos = light->light(0).pos();
+
+        fWidth = diffuseWidth;
+        fHeight = diffuseHeight;
+
+        this->registerChildProcessor(std::move(occluder));
+        this->initClassID<RadialShadowMapFP>();
+    }
+
+    class GLSLRadialShadowMapFP : public GrGLSLFragmentProcessor {
+    public:
+        GLSLRadialShadowMapFP() { }
+
+        void emitCode(EmitArgs& args) override {
+
+            GrGLSLFragmentBuilder* fragBuilder = args.fFragBuilder;
+            GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
+
+            const char* lightPosUniName = nullptr;
+
+            fLightPosUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
+                                                      kVec3f_GrSLType,
+                                                      kDefault_GrSLPrecision,
+                                                      "lightPos",
+                                                      &lightPosUniName);
+
+            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);
+
+            // Modify the input texture coordinates to index into our 1D output
+            fragBuilder->codeAppend("float distHere;");
+            fragBuilder->codeAppend("float closestDistHere = 0;");
+            fragBuilder->codeAppend("vec2 coords = vMatrixCoord_0_0_Stage0;");
+            fragBuilder->codeAppend("coords.y = 0;");
+            fragBuilder->codeAppend("vec2 destCoords = vec2(0,0);");
+            fragBuilder->codeAppendf("float step = 1.0 / %s;", heightUniName);
+
+            // assume that we are at 0, 0 light pos
+            // TODO use correct light positions
+
+            // this goes through each depth value in the final output buffer,
+            // basically raycasting outwards, and finding the first collision.
+            // we also increment coords.y to 2 instead 1 so our shadows stretch the whole screen.
+            fragBuilder->codeAppendf("for (coords.y = 0; coords.y <= 2; coords.y += step) {");
+
+                fragBuilder->codeAppend("float theta = (coords.x * 2.0 - 1.0) * 3.1415;");
+                fragBuilder->codeAppend("float r = coords.y;");
+                fragBuilder->codeAppend("destCoords = "
+                        "vec2(r * cos(theta), - r * sin(theta)) /2.0 + 0.5;");
+                fragBuilder->codeAppendf("vec2 lightOffset = (vec2(%s)/vec2(%s,%s) - 0.5)"
+                                                            "* vec2(1.0, 1.0);",
+                                         lightPosUniName, widthUniName, heightUniName);
+
+                fragBuilder->codeAppend("distHere = texture(uTextureSampler0_Stage1,"
+                                                           "destCoords + lightOffset).b;");
+                fragBuilder->codeAppend("if (distHere > 0.0) {"
+                                            "closestDistHere = coords.y;"
+                                        "break;}");
+            fragBuilder->codeAppend("}");
+
+            fragBuilder->codeAppendf("%s = vec4(vec3(closestDistHere / 2.0),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 RadialShadowMapFP &radialShadowMapFP = proc.cast<RadialShadowMapFP>();
+
+            const SkVector3& lightPos = radialShadowMapFP.lightPos();
+            if (lightPos != fLightPos) {
+                pdman.set3fv(fLightPosUni, 1, &lightPos.fX);
+                fLightPos = lightPos;
+            }
+
+            int width = radialShadowMapFP.width();
+            if (width != fWidth) {
+                pdman.set1i(fWidthUni, width);
+                fWidth = width;
+            }
+            int height = radialShadowMapFP.height();
+            if (height != fHeight) {
+                pdman.set1i(fHeightUni, height);
+                fHeight = height;
+            }
+        }
+
+    private:
+        SkVector3 fLightPos;
+        GrGLSLProgramDataManager::UniformHandle fLightPosUni;
+
+        int fWidth;
+        GrGLSLProgramDataManager::UniformHandle fWidthUni;
+        int fHeight;
+        GrGLSLProgramDataManager::UniformHandle fHeightUni;
+    };
+
+    void onGetGLSLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override {
+        GLSLRadialShadowMapFP::GenKey(*this, caps, b);
+    }
+
+    const char* name() const override { return "RadialShadowMapFP"; }
+
+    void onComputeInvariantOutput(GrInvariantOutput* inout) const override {
+        inout->mulByUnknownFourComponents();
+    }
+    const SkVector3& lightPos() const {
+        return fLightPos;
+    }
+
+    int width() const { return fWidth; }
+    int height() const { return fHeight; }
+
+private:
+    GrGLSLFragmentProcessor* onCreateGLSLInstance() const override {
+        return new GLSLRadialShadowMapFP;
+    }
+
+    bool onIsEqual(const GrFragmentProcessor& proc) const override {
+        const RadialShadowMapFP& radialShadowMapFP = proc.cast<RadialShadowMapFP>();
+
+        if (fWidth != radialShadowMapFP.fWidth || fHeight != radialShadowMapFP.fHeight) {
+            return false;
+        }
+
+        if (fLightPos != radialShadowMapFP.fLightPos) {
+            return false;
+        }
+
+        return true;
+    }
+
+    SkVector3        fLightPos;
+
+    int              fHeight;
+    int              fWidth;
+};
+
+////////////////////////////////////////////////////////////////////////////
+
+sk_sp<GrFragmentProcessor> SkRadialShadowMapShaderImpl::asFragmentProcessor
+        (const AsFPArgs& fpargs) const {
+
+    sk_sp<GrFragmentProcessor> occluderFP = fOccluderShader->asFragmentProcessor(fpargs);
+
+    sk_sp<GrFragmentProcessor> shadowFP = sk_make_sp<RadialShadowMapFP>(std::move(occluderFP),
+                                                                        fLight, fWidth, fHeight,
+                                                                        fpargs.fContext);
+    return shadowFP;
+}
+
+#endif
+
+////////////////////////////////////////////////////////////////////////////
+
+bool SkRadialShadowMapShaderImpl::isOpaque() const {
+    return fOccluderShader->isOpaque();
+}
+
+SkRadialShadowMapShaderImpl::ShadowMapRadialShaderContext::ShadowMapRadialShaderContext(
+        const SkRadialShadowMapShaderImpl& 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;
+}
+
+SkRadialShadowMapShaderImpl::ShadowMapRadialShaderContext::~ShadowMapRadialShaderContext() {
+    // 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 SkRadialShadowMapShaderImpl::ShadowMapRadialShaderContext::shadeSpan
+        (int x, int y, SkPMColor result[], int count) {
+    do {
+        int n = SkTMin(count, BUFFER_MAX);
+
+        // just fill with white for now
+        SkPMColor accum = convert(SkColor3f::Make(1.0f, 1.0f, 1.0f), 0xFF);
+
+        for (int i = 0; i < n; ++i) {
+            result[i] = accum;
+        }
+
+        result += n;
+        x += n;
+        count -= n;
+    } while (count > 0);
+}
+
+////////////////////////////////////////////////////////////////////////////
+
+#ifndef SK_IGNORE_TO_STRING
+void SkRadialShadowMapShaderImpl::toString(SkString* str) const {
+    str->appendf("RadialShadowMapShader: ()");
+}
+#endif
+
+sk_sp<SkFlattenable> SkRadialShadowMapShaderImpl::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<SkRadialShadowMapShaderImpl>(std::move(occluderShader),
+                                                   std::move(light),
+                                                   diffuseWidth, diffuseHeight);
+}
+
+void SkRadialShadowMapShaderImpl::flatten(SkWriteBuffer& buf) const {
+    this->INHERITED::flatten(buf);
+
+    fLight->flatten(buf);
+
+    buf.writeInt(fWidth);
+    buf.writeInt(fHeight);
+
+    buf.writeFlattenable(fOccluderShader.get());
+}
+
+size_t SkRadialShadowMapShaderImpl::onContextSize(const ContextRec& rec) const {
+    return sizeof(ShadowMapRadialShaderContext);
+}
+
+SkShader::Context* SkRadialShadowMapShaderImpl::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) ShadowMapRadialShaderContext(*this, rec, occluderContext, heapAllocated);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+sk_sp<SkShader> SkRadialShadowMapShader::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<SkRadialShadowMapShaderImpl>(std::move(occluderShader),
+                                                   std::move(light),
+                                                   diffuseWidth, diffuseHeight);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkRadialShadowMapShader)
+SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkRadialShadowMapShaderImpl)
+SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END
+
+///////////////////////////////////////////////////////////////////////////////
+
+#endif