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offset_converter: add threshold to avoid cutting large closed rings off

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This commit is contained in:
Mickey Rose 2012-06-25 20:29:06 +02:00
parent 61e3c4dde7
commit 9ccce2f1d9
1 changed files with 26 additions and 4 deletions
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30
include/mapnik/offset_converter.hpp
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@ -47,6 +47,7 @@ struct MAPNIK_DECL offset_converter
offset_converter(Geometry & geom)
: geom_(geom)
, offset_(0.0)
, threshold_(8.0)
, half_turn_segments_(16)
, status_(initial)
, pre_first_(vertex2d::no_init)
@ -68,15 +69,28 @@ struct MAPNIK_DECL offset_converter
return offset_;
}
void set_offset(double offset)
double get_threshold() const
{
if (offset != offset_)
return threshold_;
}
void set_offset(double value)
{
if (offset_ != value)
{
offset_ = offset;
offset_ = value;
reset();
}
}
void set_threshold(double value)
{
threshold_ = value;
// no need to reset(), since threshold doesn't affect
// offset vertices' computation, it only controls how
// far will we be looking for self-intersections
}
unsigned vertex(double * x, double * y)
{
if (offset_ == 0.0)
@ -94,6 +108,8 @@ struct MAPNIK_DECL offset_converter
if (pos_ == vertices_.size())
return output_vertex(x, y);
double const check_dist = offset_ * threshold_;
double const check_dist2 = check_dist * check_dist;
double t = 1.0;
double vt, ut;
@ -103,6 +119,11 @@ struct MAPNIK_DECL offset_converter
vertex2d const& u0 = vertices_[i];
vertex2d const& u1 = vertices_[i+1];
double const dx = u0.x - cur_.x;
double const dy = u0.y - cur_.y;
if (dx*dx + dy*dy > check_dist2)
break;
if (!intersection(pre_, cur_, &vt, u0, u1, &ut))
continue;
@ -311,7 +332,7 @@ private:
displace(v1, angle_b);
push_vertex(v1);
// initalization finished
// initialization finished
return status_ = process;
}
@ -339,6 +360,7 @@ private:
Geometry & geom_;
double offset_;
double threshold_;
unsigned half_turn_segments_;
status status_;
size_t pos_;