raster shadows

src/core/SkShadowShader.cpp

Index: src/core/SkShadowShader.cpp
diff --git a/src/core/SkShadowShader.cpp b/src/core/SkShadowShader.cpp
index 5fc992acc14dd790ab86e43e6a761ecc7b7db8bc..470df08ed7cc34205207ad97c545752079f7fea0 100644
--- a/src/core/SkShadowShader.cpp
+++ b/src/core/SkShadowShader.cpp
@@ -61,6 +61,10 @@ public:
 
         void* fHeapAllocated;
 
+        int fNonAmbLightCnt;
+        SkPixmap* fShadowMapPixels[SkShadowShader::kMaxNonAmbientLights] = {nullptr};
+
+
         typedef SkShader::Context INHERITED;
     };
 
@@ -500,6 +504,21 @@ SkShadowShaderImpl::ShadowShaderContext::ShadowShaderContext(
     }
 
     fFlags = flags;
+
+    const SkShadowShaderImpl& lightShader = static_cast<const SkShadowShaderImpl&>(fShader);
+
+    fNonAmbLightCnt = 0;
+

[robertphillips, 2016/08/24 14:48:53]

Since you're densely packing the pixmaps, let's add a numNonAmbientLights call
to SkLights and allocate them all at once. 

This will mean the later code will need to be able to handle an empty pixmap.

[vjiaoblack, 2016/08/29 15:45:48]

Done.

+    for (int i = 0; i < lightShader.fLights->numLights(); i++) {
+        if (lightShader.fLights->light(i).type() == SkLights::Light::kDirectional_LightType) {
+            fShadowMapPixels[fNonAmbLightCnt] = new SkPixmap();
+            if (!lightShader.fLights->light(i).getShadowMap()->
+                    peekPixels(fShadowMapPixels[fNonAmbLightCnt])) {

[robertphillips, 2016/08/24 14:48:53]

this assignment doesn't seem so good ...

[vjiaoblack, 2016/08/29 15:45:48]

Done.

+                fShadowMapPixels[fNonAmbLightCnt] = nullptr;
+            }
+            fNonAmbLightCnt++;
+        }
+    }
 }
 
 SkShadowShaderImpl::ShadowShaderContext::~ShadowShaderContext() {
@@ -509,6 +528,12 @@ SkShadowShaderImpl::ShadowShaderContext::~ShadowShaderContext() {
     fDiffuseContext->~Context();
 
     sk_free(fHeapAllocated);
+
+    for (int i = 0; i < SkShadowShader::kMaxNonAmbientLights; i++) {
+        if (fShadowMapPixels[i]) {
+            delete fShadowMapPixels[i];
+        }
+    }
 }
 
 static inline SkPMColor convert(SkColor3f color, U8CPU a) {
@@ -541,35 +566,70 @@ void SkShadowShaderImpl::ShadowShaderContext::shadeSpan(int x, int y,
     const SkShadowShaderImpl& lightShader = static_cast<const SkShadowShaderImpl&>(fShader);
 
     SkPMColor diffuse[BUFFER_MAX];
+    SkPMColor povDepth[BUFFER_MAX];
 
     do {
         int n = SkTMin(count, BUFFER_MAX);
 
-        fPovDepthContext->shadeSpan(x, y, diffuse, n);
         fDiffuseContext->shadeSpan(x, y, diffuse, n);
+        fPovDepthContext->shadeSpan(x, y, povDepth, n);
 
         for (int i = 0; i < n; ++i) {
-
             SkColor diffColor = SkUnPreMultiply::PMColorToColor(diffuse[i]);
+            SkColor povDepthColor = povDepth[i];
 
-            SkColor3f accum = SkColor3f::Make(0.0f, 0.0f, 0.0f);
+            SkColor3f totalColor = SkColor3f::Make(0.0f, 0.0f, 0.0f);
+            SkColor3f totalLight = SkColor3f::Make(0.0f, 0.0f, 0.0f);
             // This is all done in linear unpremul color space (each component 0..255.0f though)
+
+            fNonAmbLightCnt = 0;
             for (int l = 0; l < lightShader.fLights->numLights(); ++l) {
                 const SkLights::Light& light = lightShader.fLights->light(l);
 
-                if (SkLights::Light::kAmbient_LightType == light.type()) {
-                    accum.fX += light.color().fX * SkColorGetR(diffColor);
-                    accum.fY += light.color().fY * SkColorGetG(diffColor);
-                    accum.fZ += light.color().fZ * SkColorGetB(diffColor);
-                } else {
-                    // scaling by fZ accounts for lighting direction
-                    accum.fX += light.color().makeScale(light.dir().fZ).fX * SkColorGetR(diffColor);
-                    accum.fY += light.color().makeScale(light.dir().fZ).fY * SkColorGetG(diffColor);
-                    accum.fZ += light.color().makeScale(light.dir().fZ).fZ * SkColorGetB(diffColor);
+                if (light.type() == SkLights::Light::kDirectional_LightType) {
+                    int xOffset = SkScalarRoundToInt(light.dir().fX *
+                                                     SkIntToScalar(SkColorGetB(povDepthColor)));
+                    int yOffset = SkScalarRoundToInt(light.dir().fY *
+                                                     SkIntToScalar(SkColorGetB(povDepthColor)));
+
+                    int shX = (x + i + xOffset);
+                    int shY = (y + yOffset);
+
+                    shX = SkClampPos(shX);
+                    shY = SkClampPos(shY);
+
+                    shX = SkClampMax(shX, light.getShadowMap()->width() - 1);
+                    shY = SkClampMax(shY, light.getShadowMap()->height() - 1);
+
+                    int shDepth = 0;
+                    int pvDepth = SkColorGetB(povDepthColor); // depth stored in blue channel
+
+                    if (fShadowMapPixels[fNonAmbLightCnt]) {
+                        uint32_t pix = *fShadowMapPixels[fNonAmbLightCnt]->addr32(shX, shY);
+                        SkColor shColor(pix);
+
+                        shDepth += SkColorGetB(shColor);
+                    } else {
+                        // TODO: handle not being able to read shadow map pixels
+                    }
+
+                    if (pvDepth >= shDepth) {
+                        // assume object normals are pointing straight up
+                        totalLight.fX += light.dir().fZ * light.color().fX;
+                        totalLight.fY += light.dir().fZ * light.color().fY;
+                        totalLight.fZ += light.dir().fZ * light.color().fZ;
+                    }
+                    fNonAmbLightCnt++;
+                } else if (light.type() == SkLights::Light::kAmbient_LightType) {
+                    totalLight += light.color();
                 }
             }
 
-            result[i] = convert(accum, SkColorGetA(diffColor));
+            totalColor.fX += SkColorGetR(diffColor) * totalLight.fX;
+            totalColor.fY += SkColorGetG(diffColor) * totalLight.fY;
+            totalColor.fZ += SkColorGetB(diffColor) * totalLight.fZ;
+
+            result[i] = convert(totalColor, SkColorGetA(diffColor));
         }
 
         result += n;