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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 cc {
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;
};
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 cc
#endif // #define CCMathUtil_h
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