added point light attenuations to raster

src/core/SkShadowShader.cpp

 /*
  * 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 "SkCanvas.h"
 #include "SkReadBuffer.h"
 #include "SkShadowShader.h"
@@ skipping 701 matching lines @@
         for (int i = 0; i < n; ++i) {
             SkColor diffColor = SkUnPreMultiply::PMColorToColor(diffuse[i]);
             SkColor povDepthColor = povDepth[i];
 
             SkColor3f totalLight = lightShader.fLights->ambientLightColor();
             // 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 SkLights::Light& light = lightShader.fLights->light(l);
 
+                int pvDepth = SkColorGetB(povDepthColor); // depth stored in blue channel
+
                 if (light.type() == SkLights::Light::kDirectional_LightType) {
-                    int pvDepth = SkColorGetB(povDepthColor); // depth stored in blue channel
 
                     int xOffset = SkScalarRoundToInt(light.dir().fX * pvDepth);
                     int yOffset = SkScalarRoundToInt(light.dir().fY * pvDepth);
 
                     int shX = SkClampMax(x + i + xOffset, light.getShadowMap()->width() - 1);
                     int shY = SkClampMax(y + yOffset, light.getShadowMap()->height() - 1);
 
                     int shDepth = 0;
                     int shDepthsq = 0;
 
@@ skipping 24 matching lines @@
                             lightProb = SkMaxScalar((lightProb - bias) / (1.0f - bias), 0.0f);
                         } else {
                             lightProb = 0.0f;
                         }
                     }
 
                     // assume object normals are pointing straight up
                     totalLight.fX += light.dir().fZ * light.color().fX * lightProb;
                     totalLight.fY += light.dir().fZ * light.color().fY * lightProb;
                     totalLight.fZ += light.dir().fZ * light.color().fZ * lightProb;
+
                 } else {
-                    totalLight += light.color();
+                    // right now we only expect directional and point light types.
+                    SkASSERT(light.type() == SkLights::Light::kPoint_LightType);
+
+                    int height = lightShader.fDiffuseHeight;
+
+                    SkVector3 fragToLight = SkVector3::Make(light.pos().fX - x - i,
+                                                            light.pos().fY - (height - y),
+                                                            light.pos().fZ - pvDepth);
+
+                    SkScalar dist = fragToLight.length();
+                    SkScalar normalizedZ = fragToLight.fZ / dist;
+
+                    SkScalar distAttenuation = light.intensity() / (1.0f + dist * dist);
+
+                    // assume object normals are pointing straight up
+                    totalLight.fX += normalizedZ * light.color().fX * distAttenuation;
+                    totalLight.fY += normalizedZ * light.color().fY * distAttenuation;
+                    totalLight.fZ += normalizedZ * light.color().fZ * distAttenuation;
                 }
             }
 
             SkColor3f totalColor = SkColor3f::Make(SkColorGetR(diffColor) * totalLight.fX,
                                                    SkColorGetG(diffColor) * totalLight.fY,
                                                    SkColorGetB(diffColor) * totalLight.fZ);
 
             result[i] = convert(totalColor, SkColorGetA(diffColor));
         }
 
@@ skipping 110 matching lines @@
 
 ///////////////////////////////////////////////////////////////////////////////
 
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkShadowShader)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkShadowShaderImpl)
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END
 
 ///////////////////////////////////////////////////////////////////////////////
 
 #endif