Raster implementation of diffuse and specular lighting filters. Externally,

the caller instantiates a light (distant, point or spot), and an
SkDiffuseLightingFilter or SkSpecularLightingImageFilter with that light.  A
Sobel edge detection filter is applied to the alpha of the incoming bitmap, and
the result is used as a height map for lighting calculations.

Review URL:  http://codereview.appspot.com/6302101/



git-svn-id: http://skia.googlecode.com/svn/trunk@4314 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 87 insertions, 0 deletions

diff --git a/include/effects/SkLightingImageFilter.h b/include/effects/SkLightingImageFilter.h
new file mode 100644
index 0000000000..f8a5ccf4af
--- /dev/null
+++ b/include/effects/SkLightingImageFilter.h
@@ -0,0 +1,87 @@
+/*
+ * Copyright 2012 The Android Open Source Project
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+
+#ifndef SkLightingImageFilter_DEFINED
+#define SkLightingImageFilter_DEFINED
+
+#include "SkImageFilter.h"
+#include "SkColor.h"
+
+class SK_API SkPoint3 {
+public:
+    SkPoint3() {}
+    SkPoint3(SkScalar x, SkScalar y, SkScalar z)
+      : fX(x), fY(y), fZ(z) {}
+    SkScalar dot(const SkPoint3& other) const {
+        return SkScalarMul(fX, other.fX)
+             + SkScalarMul(fY, other.fY)
+             + SkScalarMul(fZ, other.fZ);
+    }
+    SkScalar maxComponent() const {
+        return fX > fY ? (fX > fZ ? fX : fZ) : (fY > fZ ? fY : fZ);
+    }
+    void normalize() {
+        SkScalar scale = SkScalarInvert(SkScalarSqrt(dot(*this)));
+        fX = SkScalarMul(fX, scale);
+        fY = SkScalarMul(fY, scale);
+        fZ = SkScalarMul(fZ, scale);
+    }
+    SkPoint3 operator*(SkScalar scalar) const {
+        return SkPoint3(SkScalarMul(fX, scalar),
+                        SkScalarMul(fY, scalar),
+                        SkScalarMul(fZ, scalar));
+    }
+    SkPoint3 operator-(const SkPoint3& other) const {
+        return SkPoint3(fX - other.fX, fY - other.fY, fZ - other.fZ);
+    }
+    SkScalar fX, fY, fZ;
+};
+
+class SkLight;
+
+class SK_API SkLightingImageFilter : public SkImageFilter {
+public:
+    static SkImageFilter* CreateDistantLitDiffuse(const SkPoint3& direction,
+        const SkColor& lightColor, SkScalar surfaceScale, SkScalar kd);
+    static SkImageFilter* CreatePointLitDiffuse(SkPoint3& location,
+        const SkColor& lightColor, SkScalar surfaceScale, SkScalar kd);
+    static SkImageFilter* CreateSpotLitDiffuse(const SkPoint3& location,
+        const SkPoint3& target, SkScalar specularExponent, SkScalar cutoffAngle,
+        const SkColor& lightColor, SkScalar surfaceScale, SkScalar kd);
+    static SkImageFilter* CreateDistantLitSpecular(const SkPoint3& direction,
+        const SkColor& lightColor, SkScalar surfaceScale, SkScalar ks,
+        SkScalar shininess);
+    static SkImageFilter* CreatePointLitSpecular(SkPoint3& location,
+        const SkColor& lightColor, SkScalar surfaceScale, SkScalar ks,
+        SkScalar shininess);
+    static SkImageFilter* CreateSpotLitSpecular(const SkPoint3& location,
+        const SkPoint3& target, SkScalar specularExponent, SkScalar cutoffAngle,
+        const SkColor& lightColor, SkScalar surfaceScale, SkScalar ks,
+        SkScalar shininess);
+    ~SkLightingImageFilter();
+
+    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkLightingImageFilter)
+
+protected:
+    SkLightingImageFilter(SkLight* light, const SkColor& lightColor,
+                          SkScalar surfaceScale);
+    explicit SkLightingImageFilter(SkFlattenableReadBuffer& buffer);
+    virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;
+    const SkLight* light() const { return fLight; }
+    const SkPoint3& lightColor() const { return fLightColor; }
+    SkScalar surfaceScale() const { return fSurfaceScale; }
+
+private:
+    typedef SkImageFilter INHERITED;
+    SkLight* fLight;
+    SkPoint3 fLightColor;
+    SkScalar fSurfaceScale;
+};
+
+#endif
+