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Work around a limitation of gc_calc_course_dist(). When the start and end

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points are too close together, this routine can return a course of "nan"
but the distance is valid.  Someday someone who understands the math should
rewrite the gc_calc_course_dist() routine so it is more robust, but for now
it's easiest to simply check for a nan result and code around the limitation.
This commit is contained in:
curt
2004-03-03 21:37:41 +00:00
parent 9f59e956fa
commit a460c753e7
2 changed files with 20 additions and 6 deletions
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23
simgear/scene/sky/cloud.cxx
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@@ -21,6 +21,8 @@
#include <stdio.h>
#include STL_IOSTREAM
#include <math.h>
#include <plib/sg.h>
#include <plib/ssg.h>
@@ -363,6 +365,17 @@ bool SGCloudLayer::reposition( sgVec3 p, sgVec3 up, double lon, double lat,
calc_gc_course_dist( dest, start, &course, &dist );
// cout << "course = " << course << ", dist = " << dist << endl;
// if start and dest are too close together,
// calc_gc_course_dist() can return a course of "nan". If
// this happens, lets just use the last known good course.
// This is a hack, and it would probably be better to make
// calc_gc_course_dist() more robust.
if ( isnan(course) ) {
course = last_course;
} else {
last_course = course;
}
// calculate cloud movement due to external forces
double ax = 0.0, ay = 0.0, bx = 0.0, by = 0.0;
@@ -396,9 +409,10 @@ bool SGCloudLayer::reposition( sgVec3 p, sgVec3 up, double lon, double lat,
if ( base[0] > -10.0 && base[0] < 10.0 ) {
base[0] -= (int)base[0];
} else {
base[0] = 0.0;
SG_LOG(SG_ASTRO, SG_DEBUG,
"Error: base = " << base[0] << "," << base[1]);
"Error: base = " << base[0] << "," << base[1] <<
" course = " << course << " dist = " << dist );
base[0] = 0.0;
}
base[1] += yoff;
@@ -409,9 +423,10 @@ bool SGCloudLayer::reposition( sgVec3 p, sgVec3 up, double lon, double lat,
if ( base[1] > -10.0 && base[1] < 10.0 ) {
base[1] -= (int)base[1];
} else {
base[1] = 0.0;
SG_LOG(SG_ASTRO, SG_ALERT,
"Error: base = " << base[0] << "," << base[1]);
"Error: base = " << base[0] << "," << base[1] <<
" course = " << course << " dist = " << dist );
base[1] = 0.0;
}
// cout << "base = " << base[0] << "," << base[1] << endl;

3
simgear/scene/sky/cloud.hxx
View File

@@ -194,8 +194,7 @@ private:
// from winds, and to simulate the clouds being tied to ground
// position, not view position
// double xoff, yoff;
double last_lon, last_lat;
double last_lon, last_lat, last_course;
};