From 698ca7b1a6274587b11d6ce4634621f625100269 Mon Sep 17 00:00:00 2001
From: curt <curt>
Date: Wed, 29 Nov 2000 20:17:27 +0000
Subject: [PATCH] Fixed a problem with dividing the tile up into land use areas
(original scheme left really tiny slivers on the edges.)
---
src/BuildTiles/Main/main.cxx | 50 ++++++++++++++++++++++++------------
1 file changed, 33 insertions(+), 17 deletions(-)
diff --git a/src/BuildTiles/Main/main.cxx b/src/BuildTiles/Main/main.cxx
index 3f769219..bafc56b7 100644
--- a/src/BuildTiles/Main/main.cxx
+++ b/src/BuildTiles/Main/main.cxx
@@ -219,6 +219,30 @@ static void inline add_to_polys ( FGPolygon &accum, const FGPolygon &poly) {
}
+// make the area specified area, look up the land cover type, and add
+// it to polys
+static void make_area( const LandCover &cover, FGPolygon *polys,
+ double x1, double y1, double x2, double y2,
+ double half_dx, double half_dy )
+{
+ // Look up the land cover for the square
+ int cover_value = cover.getValue( x1 + half_dx, y1 + half_dy );
+ cout << " position: " << x1 << ',' << y1 << ','
+ << cover.getDescUSGS(cover_value) << endl;
+ AreaType area = translateUSGSCover(cover_value);
+ if (area != DefaultArea) {
+ // Create a square polygon and merge it into the list.
+ FGPolygon poly;
+ poly.erase();
+ poly.add_node(0, Point3D(x1, y1, 0.0));
+ poly.add_node(0, Point3D(x1, y2, 0.0));
+ poly.add_node(0, Point3D(x2, y2, 0.0));
+ poly.add_node(0, Point3D(x2, y1, 0.0));
+ add_to_polys(polys[area], poly);
+ }
+}
+
+
// Generate polygons from la and-cover raster. Horizontally- or
// vertically-adjacent polygons will be merged automatically.
static int actual_load_landcover ( FGConstruct & c,
@@ -245,6 +269,9 @@ static int actual_load_landcover ( FGConstruct & c,
double dx = 1.0 / 120.0;
double dy = dx;
+ double half_dx = dx * 0.5;
+ double half_dy = half_dx;
+
// Figure out how many units wide and high this tile is; each unit
// is 30 arc seconds.
// int x_span = int(120 * bucket_span(base_lat)); // arcsecs of longitude
@@ -255,32 +282,21 @@ static int actual_load_landcover ( FGConstruct & c,
double x2 = x1 + dx;
double y2 = y1 + dy;
- while ( x1 < max_lon ) {
- while ( y1 < max_lat ) {
- // Look up the land cover for the square
- int cover_value = cover.getValue(x1 + (1.0/240.0),
- y1 + (1.0/240.0));
- cout << " position: " << x1 << ',' << y1 << ','
- << cover.getDescUSGS(cover_value) << endl;
- AreaType area = translateUSGSCover(cover_value);
- if (area != DefaultArea) {
- // Create a square polygon and merge it into the list.
- poly.erase();
- poly.add_node(0, Point3D(x1, y1, 0.0));
- poly.add_node(0, Point3D(x1, y2, 0.0));
- poly.add_node(0, Point3D(x2, y2, 0.0));
- poly.add_node(0, Point3D(x2, y1, 0.0));
- add_to_polys(polys[area], poly);
- }
+ while ( x1 < max_lon - (dx + half_dx) ) {
+ while ( y1 < max_lat - (dy + half_dy) ) {
+ make_area( cover, polys, x1, y1, x2, y2, half_dx, half_dy );
y1 = y2;
y2 += dy;
}
+ make_area( cover, polys, x1, y1, x2, max_lat, half_dx, half_dy );
+
x1 = x2;
x2 += dx;
y1 = base_lat;
y2 = y1 + dy;
}
+ make_area( cover, polys, x1, y1, max_lon, max_lat, half_dx, half_dy );
// Now that we're finished looking up land cover, we have a list
// of lists of polygons, one (possibly-empty) list for each area