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/*
* Copyright (C) 2012 Adobe Systems Incorporated. All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
* COPYRIGHT HOLDER OR 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 "third_party/blink/renderer/platform/geometry/float_polygon.h"
#include <memory>
#include "third_party/blink/renderer/platform/wtf/math_extras.h"
namespace blink {
static inline bool AreCollinearPoints(const gfx::PointF& p0,
const gfx::PointF& p1,
const gfx::PointF& p2) {
return !gfx::CrossProduct(p1 - p0, p2 - p0);
}
static inline bool AreCoincidentPoints(const gfx::PointF& p0,
const gfx::PointF& p1) {
return p0.x() == p1.x() && p0.y() == p1.y();
}
static inline unsigned NextVertexIndex(unsigned vertex_index,
unsigned n_vertices,
bool clockwise) {
return ((clockwise) ? vertex_index + 1 : vertex_index - 1 + n_vertices) %
n_vertices;
}
static unsigned FindNextEdgeVertexIndex(const FloatPolygon& polygon,
unsigned vertex_index1,
bool clockwise) {
unsigned n_vertices = polygon.NumberOfVertices();
unsigned vertex_index2 =
NextVertexIndex(vertex_index1, n_vertices, clockwise);
while (vertex_index2 && AreCoincidentPoints(polygon.VertexAt(vertex_index1),
polygon.VertexAt(vertex_index2)))
vertex_index2 = NextVertexIndex(vertex_index2, n_vertices, clockwise);
while (vertex_index2) {
unsigned vertex_index3 =
NextVertexIndex(vertex_index2, n_vertices, clockwise);
if (!AreCollinearPoints(polygon.VertexAt(vertex_index1),
polygon.VertexAt(vertex_index2),
polygon.VertexAt(vertex_index3)))
break;
vertex_index2 = vertex_index3;
}
return vertex_index2;
}
FloatPolygon::FloatPolygon(Vector<gfx::PointF> vertices)
: vertices_(std::move(vertices)) {
unsigned n_vertices = NumberOfVertices();
edges_.resize(n_vertices);
empty_ = n_vertices < 3;
if (n_vertices)
bounding_box_.set_origin(VertexAt(0));
if (empty_)
return;
unsigned min_vertex_index = 0;
for (unsigned i = 1; i < n_vertices; ++i) {
const gfx::PointF& vertex = VertexAt(i);
if (vertex.y() < VertexAt(min_vertex_index).y() ||
(vertex.y() == VertexAt(min_vertex_index).y() &&
vertex.x() < VertexAt(min_vertex_index).x()))
min_vertex_index = i;
}
gfx::PointF next_vertex = VertexAt((min_vertex_index + 1) % n_vertices);
gfx::PointF prev_vertex =
VertexAt((min_vertex_index + n_vertices - 1) % n_vertices);
bool clockwise = gfx::CrossProduct(VertexAt(min_vertex_index) - prev_vertex,
next_vertex - prev_vertex) > 0;
unsigned edge_index = 0;
unsigned vertex_index1 = 0;
do {
bounding_box_.UnionEvenIfEmpty(
gfx::RectF(VertexAt(vertex_index1), gfx::SizeF()));
unsigned vertex_index2 =
FindNextEdgeVertexIndex(*this, vertex_index1, clockwise);
edges_[edge_index].polygon_ = this;
edges_[edge_index].vertex_index1_ = vertex_index1;
edges_[edge_index].vertex_index2_ = vertex_index2;
edges_[edge_index].edge_index_ = edge_index;
++edge_index;
vertex_index1 = vertex_index2;
} while (vertex_index1);
if (edge_index > 3) {
const FloatPolygonEdge& first_edge = edges_[0];
const FloatPolygonEdge& last_edge = edges_[edge_index - 1];
if (AreCollinearPoints(last_edge.Vertex1(), last_edge.Vertex2(),
first_edge.Vertex2())) {
edges_[0].vertex_index1_ = last_edge.vertex_index1_;
edge_index--;
}
}
edges_.resize(edge_index);
empty_ = edges_.size() < 3;
if (empty_)
return;
for (unsigned i = 0; i < edges_.size(); ++i) {
FloatPolygonEdge* edge = &edges_[i];
edge_tree_.Add(EdgeInterval(edge->MinY(), edge->MaxY(), edge));
}
}
bool FloatPolygon::OverlappingEdges(
float min_y,
float max_y,
Vector<const FloatPolygonEdge*>& result) const {
Vector<FloatPolygon::EdgeInterval> overlapping_edge_intervals;
edge_tree_.AllOverlaps(FloatPolygon::EdgeInterval(min_y, max_y, 0),
overlapping_edge_intervals);
unsigned overlapping_edge_intervals_size = overlapping_edge_intervals.size();
result.resize(overlapping_edge_intervals_size);
for (unsigned i = 0; i < overlapping_edge_intervals_size; ++i) {
const FloatPolygonEdge* edge = static_cast<const FloatPolygonEdge*>(
overlapping_edge_intervals[i].Data());
DCHECK(edge);
result[i] = edge;
}
return overlapping_edge_intervals_size > 0;
}
bool VertexPair::Intersection(const VertexPair& other,
gfx::PointF& point) const {
// See: http://paulbourke.net/geometry/pointlineplane/,
// "Intersection point of two lines in 2 dimensions"
gfx::Vector2dF this_delta = Vertex2() - Vertex1();
gfx::Vector2dF other_delta = other.Vertex2() - other.Vertex1();
float denominator = gfx::CrossProduct(this_delta, other_delta);
if (!denominator)
return false;
// The two line segments: "this" vertex1,vertex2 and "other" vertex1,vertex2,
// have been defined in parametric form. Each point on the line segment is:
// vertex1 + u * (vertex2 - vertex1), when 0 <= u <= 1. We're computing the
// values of u for each line at their intersection point.
gfx::Vector2dF vertex1_delta = Vertex1() - other.Vertex1();
float u_this_line =
gfx::CrossProduct(other_delta, vertex1_delta) / denominator;
float u_other_line =
gfx::CrossProduct(this_delta, vertex1_delta) / denominator;
if (u_this_line < 0 || u_other_line < 0 || u_this_line > 1 ||
u_other_line > 1)
return false;
point = Vertex1() + gfx::ScaleVector2d(this_delta, u_this_line);
return true;
}
} // namespace blink
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