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diff --git a/cc/CCMathUtil.h b/cc/CCMathUtil.h
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+++ b/cc/CCMathUtil.h
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+// Copyright 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CCMathUtil_h
+#define CCMathUtil_h
+
+#include "FloatPoint.h"
+#include "FloatPoint3D.h"
+
+namespace WebKit {
+class WebTransformationMatrix;
+}
+
+namespace WebCore {
+
+class IntRect;
+class FloatRect;
+class FloatQuad;
+
+struct HomogeneousCoordinate {
+    HomogeneousCoordinate(double newX, double newY, double newZ, double newW)
+        : x(newX)
+        , y(newY)
+        , z(newZ)
+        , w(newW)
+    {
+    }
+
+    bool shouldBeClipped() const
+    {
+        return w <= 0;
+    }
+
+    FloatPoint cartesianPoint2d() const
+    {
+        if (w == 1)
+            return FloatPoint(x, y);
+
+        // For now, because this code is used privately only by CCMathUtil, it should never be called when w == 0, and we do not yet need to handle that case.
+        ASSERT(w);
+        double invW = 1.0 / w;
+        return FloatPoint(x * invW, y * invW);
+    }
+
+    FloatPoint3D cartesianPoint3d() const
+    {
+        if (w == 1)
+            return FloatPoint3D(x, y, z);
+
+        // For now, because this code is used privately only by CCMathUtil, it should never be called when w == 0, and we do not yet need to handle that case.
+        ASSERT(w);
+        double invW = 1.0 / w;
+        return FloatPoint3D(x * invW, y * invW, z * invW);
+    }
+
+    double x;
+    double y;
+    double z;
+    double w;
+};
+
+// This class contains math helper functionality that does not belong in WebCore.
+// It is possible that this functionality should be migrated to WebCore eventually.
+class CCMathUtil {
+public:
+
+    // Background: WebTransformationMatrix code in WebCore does not do the right thing in
+    // mapRect / mapQuad / projectQuad when there is a perspective projection that causes
+    // one of the transformed vertices to go to w < 0. In those cases, it is necessary to
+    // perform clipping in homogeneous coordinates, after applying the transform, before
+    // dividing-by-w to convert to cartesian coordinates.
+    //
+    // These functions return the axis-aligned rect that encloses the correctly clipped,
+    // transformed polygon.
+    static IntRect mapClippedRect(const WebKit::WebTransformationMatrix&, const IntRect&);
+    static FloatRect mapClippedRect(const WebKit::WebTransformationMatrix&, const FloatRect&);
+    static FloatRect projectClippedRect(const WebKit::WebTransformationMatrix&, const FloatRect&);
+
+    // Returns an array of vertices that represent the clipped polygon. After returning, indexes from
+    // 0 to numVerticesInClippedQuad are valid in the clippedQuad array. Note that
+    // numVerticesInClippedQuad may be zero, which means the entire quad was clipped, and
+    // none of the vertices in the array are valid.
+    static void mapClippedQuad(const WebKit::WebTransformationMatrix&, const FloatQuad& srcQuad, FloatPoint clippedQuad[8], int& numVerticesInClippedQuad);
+
+    static FloatRect computeEnclosingRectOfVertices(FloatPoint vertices[], int numVertices);
+    static FloatRect computeEnclosingClippedRect(const HomogeneousCoordinate& h1, const HomogeneousCoordinate& h2, const HomogeneousCoordinate& h3, const HomogeneousCoordinate& h4);
+
+    // NOTE: These functions do not do correct clipping against w = 0 plane, but they
+    // correctly detect the clipped condition via the boolean clipped.
+    static FloatQuad mapQuad(const WebKit::WebTransformationMatrix&, const FloatQuad&, bool& clipped);
+    static FloatPoint mapPoint(const WebKit::WebTransformationMatrix&, const FloatPoint&, bool& clipped);
+    static FloatPoint3D mapPoint(const WebKit::WebTransformationMatrix&, const FloatPoint3D&, bool& clipped);
+    static FloatQuad projectQuad(const WebKit::WebTransformationMatrix&, const FloatQuad&, bool& clipped);
+    static FloatPoint projectPoint(const WebKit::WebTransformationMatrix&, const FloatPoint&, bool& clipped);
+
+    static void flattenTransformTo2d(WebKit::WebTransformationMatrix&);
+
+    // Returns the smallest angle between the given two vectors in degrees. Neither vector is
+    // assumed to be normalized.
+    static float smallestAngleBetweenVectors(const FloatSize&, const FloatSize&);
+
+    // Projects the |source| vector onto |destination|. Neither vector is assumed to be normalized.
+    static FloatSize projectVector(const FloatSize& source, const FloatSize& destination);
+};
+
+} // namespace WebCore
+
+#endif // #define CCMathUtil_h