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Fix an "unfortunate" bug in the binary polygon partitioning scheme that

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caused missing output (and thus missing scenery features.)  This could
also lead to cracks in the scenery because of the nature of the underlying
edge matching system.
This commit is contained in:
curt 2004-05-19 18:47:00 +00:00
parent 08f9a12765
commit d5689be4e7
1 changed files with 83 additions and 7 deletions
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78
src/Lib/Polygon/chop-bin.cxx
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@ -208,7 +208,8 @@ void tgChopNormalPolygon( const string& path, AreaType area,
if ( (dx > 2880) || (dy > 1440) )
throw sg_exception("something is really wrong in split_polygon()!!!!");
// write each out polygon for each bucket
if ( dy <= 1 ) {
// we are down to at most two rows, write each column and then bail
for ( j = 0; j <= dy; ++j ) {
for ( i = 0; i <= dx; ++i ) {
b_cur = sgBucketOffset(min.x(), min.y(), i, j);
@ -216,6 +217,81 @@ void tgChopNormalPolygon( const string& path, AreaType area,
preserve3d );
}
}
return;
}
// we have two or more rows left, split in half (along a
// horizontal dividing line) and recurse with each half
// find mid point (integer math)
int mid = (dy + 1) / 2 - 1;
// determine horizontal clip line
SGBucket b_clip = sgBucketOffset(min.x(), min.y(), 0, mid);
double clip_line = b_clip.get_center_lat();
if ( (clip_line >= -89.0) && (clip_line < 89.0) ) {
clip_line += SG_HALF_BUCKET_SPAN;
} else if ( clip_line < -89.0 ) {
clip_line = -89.0;
} else if ( clip_line >= 89.0 ) {
clip_line = 90.0;
} else {
SG_LOG ( SG_GENERAL, SG_ALERT,
"Out of range latitude in clip_and_write_poly() = "
<< clip_line );
}
{
//
// Crop bottom area (hopefully by putting this in it's own
// scope we can shorten the life of some really large data
// structures to reduce memory use)
//
SG_LOG ( SG_GENERAL, SG_DEBUG,
"Generating bottom half (" << min.y() << "-" <<
clip_line << ")" );
TGPolygon bottom, bottom_clip;
bottom.erase();
bottom_clip.erase();
bottom.add_node( 0, Point3D(-180.0, min.y(), 0) );
bottom.add_node( 0, Point3D(180.0, min.y(), 0) );
bottom.add_node( 0, Point3D(180.0, clip_line, 0) );
bottom.add_node( 0, Point3D(-180.0, clip_line, 0) );
bottom_clip = tgPolygonInt( bottom, shape );
tgChopNormalPolygon( path, area, bottom_clip, preserve3d );
}
{
//
// Crop top area (hopefully by putting this in it's own scope
// we can shorten the life of some really large data
// structures to reduce memory use)
//
SG_LOG ( SG_GENERAL, SG_DEBUG,
"Generating top half (" << clip_line << "-" <<
max.y() << ")" );
TGPolygon top, top_clip;
top.erase();
top_clip.erase();
top.add_node( 0, Point3D(-180.0, clip_line, 0) );
top.add_node( 0, Point3D(180.0, clip_line, 0) );
top.add_node( 0, Point3D(180.0, max.y(), 0) );
top.add_node( 0, Point3D(-180.0, max.y(), 0) );
top_clip = tgPolygonInt( top, shape );
tgChopNormalPolygon( path, area, top_clip, preserve3d );
}
}