Add SkLights class

include/core/SkLights.h

Index: include/core/SkLights.h
diff --git a/include/core/SkLights.h b/include/core/SkLights.h
new file mode 100644
index 0000000000000000000000000000000000000000..0a4fb8153e6735ca32fbe5ede5bf6b0546af89b3
--- /dev/null
+++ b/include/core/SkLights.h
@@ -0,0 +1,86 @@
+
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkLights_DEFINED
+#define SkLights_DEFINED
+
+#include "SkPoint3.h"
+#include "SkRefCnt.h"
+#include "../private/SkTDArray.h"
+
+class SK_API SkLights  : public SkRefCnt {
+public:
+    class Light {
+    public:
+        enum LightType {
+            kAmbient_LightType,       // only 'fColor' is used
+            kDirectional_LightType
+        };
+
+        Light(const SkColor3f& color)
+            : fType(kAmbient_LightType)
+            , fColor(color) {
+            fDirection.set(0.0f, 0.0f, 1.0f);
+        }
+
+        Light(const SkColor3f& color, const SkVector3& dir)
+            : fType(kDirectional_LightType)
+            , fColor(color)
+            , fDirection(dir) {
+            if (!fDirection.normalize()) {
+                fDirection.set(0.0f, 0.0f, 1.0f);
+            }
+        }
+
+        LightType type() const { return fType; }
+        const SkColor3f& color() const { return fColor; }
+        const SkVector3& dir() const { 
+            SkASSERT(kAmbient_LightType != fType);
+            return fDirection; 
+        }
+
+    private:
+        LightType   fType;
+        SkColor3f   fColor;           // linear (unpremul) color. Range is 0..1 in each channel.
+        SkVector3   fDirection;       // direction towards the light (+Z is out of the screen).
+                                      // If degenerate, it will be replaced with (0, 0, 1).
+    };
+
+    class Builder {
+    public:
+        Builder() : fLights(new SkLights) { }
+    
+        void add(const Light& light) {
+            if (fLights) {
+                *fLights->fLights.push() = light;
+            }
+        }
+
+        const sk_sp<SkLights> finish() {
+            return fLights;
+        }
+
+    private:
+        sk_sp<SkLights> fLights;
+    };
+
+    int numLights() const {
+        return fLights.count();
+    }
+
+    const Light& light(int index) const {
+        return fLights[index];
+    }
+
+private:
+    SkLights() {}
+
+    SkTDArray<Light> fLights;
+};
+
+#endif