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/*
* Copyright (C) 2008 Apple Inc. All rights reserved.
* Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies)
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "FloatQuad.h"
#include <algorithm>
#include <limits>
using namespace std;
namespace WebCore {
static inline float min4(float a, float b, float c, float d)
{
return min(min(a, b), min(c, d));
}
static inline float max4(float a, float b, float c, float d)
{
return max(max(a, b), max(c, d));
}
inline float dot(const FloatSize& a, const FloatSize& b)
{
return a.width() * b.width() + a.height() * b.height();
}
inline float determinant(const FloatSize& a, const FloatSize& b)
{
return a.width() * b.height() - a.height() * b.width();
}
inline bool isPointInTriangle(const FloatPoint& p, const FloatPoint& t1, const FloatPoint& t2, const FloatPoint& t3)
{
// Compute vectors
FloatSize v0 = t3 - t1;
FloatSize v1 = t2 - t1;
FloatSize v2 = p - t1;
// Compute dot products
float dot00 = dot(v0, v0);
float dot01 = dot(v0, v1);
float dot02 = dot(v0, v2);
float dot11 = dot(v1, v1);
float dot12 = dot(v1, v2);
// Compute barycentric coordinates
float invDenom = 1.0f / (dot00 * dot11 - dot01 * dot01);
float u = (dot11 * dot02 - dot01 * dot12) * invDenom;
float v = (dot00 * dot12 - dot01 * dot02) * invDenom;
// Check if point is in triangle
return (u >= 0) && (v >= 0) && (u + v <= 1);
}
FloatRect FloatQuad::boundingBox() const
{
float left = min4(m_p1.x(), m_p2.x(), m_p3.x(), m_p4.x());
float top = min4(m_p1.y(), m_p2.y(), m_p3.y(), m_p4.y());
float right = max4(m_p1.x(), m_p2.x(), m_p3.x(), m_p4.x());
float bottom = max4(m_p1.y(), m_p2.y(), m_p3.y(), m_p4.y());
return FloatRect(left, top, right - left, bottom - top);
}
static inline bool withinEpsilon(float a, float b)
{
return fabs(a - b) < numeric_limits<float>::epsilon();
}
bool FloatQuad::isRectilinear() const
{
return (withinEpsilon(m_p1.x(), m_p2.x()) && withinEpsilon(m_p2.y(), m_p3.y()) && withinEpsilon(m_p3.x(), m_p4.x()) && withinEpsilon(m_p4.y(), m_p1.y()))
|| (withinEpsilon(m_p1.y(), m_p2.y()) && withinEpsilon(m_p2.x(), m_p3.x()) && withinEpsilon(m_p3.y(), m_p4.y()) && withinEpsilon(m_p4.x(), m_p1.x()));
}
bool FloatQuad::containsPoint(const FloatPoint& p) const
{
return isPointInTriangle(p, m_p1, m_p2, m_p3) || isPointInTriangle(p, m_p1, m_p3, m_p4);
}
// Note that we only handle convex quads here.
bool FloatQuad::containsQuad(const FloatQuad& other) const
{
return containsPoint(other.p1()) && containsPoint(other.p2()) && containsPoint(other.p3()) && containsPoint(other.p4());
}
static inline FloatPoint rightMostCornerToVector(const FloatRect& rect, const FloatSize& vector)
{
// Return the corner of the rectangle that if it is to the left of the vector
// would mean all of the rectangle is to the left of the vector.
// The vector here represents the side between two points in a clockwise convex polygon.
//
// Q XXX
// QQQ XXX If the lower left corner of X is left of the vector that goes from the top corner of Q to
// QQQ the right corner of Q, then all of X is left of the vector, and intersection impossible.
// Q
//
FloatPoint point;
if (vector.width() >= 0)
point.setY(rect.maxY());
else
point.setY(rect.y());
if (vector.height() >= 0)
point.setX(rect.x());
else
point.setX(rect.maxX());
return point;
}
bool FloatQuad::intersectsRect(const FloatRect& rect) const
{
// For each side of the quad clockwise we check if the rectangle is to the left of it
// since only content on the right can onlap with the quad.
// This only works if the quad is convex.
FloatSize v1, v2, v3, v4;
// Ensure we use clockwise vectors.
if (!isCounterclockwise()) {
v1 = m_p2 - m_p1;
v2 = m_p3 - m_p2;
v3 = m_p4 - m_p3;
v4 = m_p1 - m_p4;
} else {
v1 = m_p4 - m_p1;
v2 = m_p1 - m_p2;
v3 = m_p2 - m_p3;
v4 = m_p3 - m_p4;
}
FloatPoint p = rightMostCornerToVector(rect, v1);
if (determinant(v1, p - m_p1) < 0)
return false;
p = rightMostCornerToVector(rect, v2);
if (determinant(v2, p - m_p2) < 0)
return false;
p = rightMostCornerToVector(rect, v3);
if (determinant(v3, p - m_p3) < 0)
return false;
p = rightMostCornerToVector(rect, v4);
if (determinant(v4, p - m_p4) < 0)
return false;
// If not all of the rectangle is outside one of the quad's four sides, then that means at least
// a part of the rectangle is overlapping the quad.
return true;
}
bool FloatQuad::isCounterclockwise() const
{
// Return if the two first vectors are turning clockwise. If the quad is convex then all following vectors will turn the same way.
return determinant(m_p2 - m_p1, m_p3 - m_p2) < 0;
}
} // namespace WebCore
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