double Projector::findPA( SkyObject *o, float x, float y ) const
{
//Find position angle of North using a test point displaced to the north
//displace by 100/zoomFactor radians (so distance is always 100 pixels)
//this is 5730/zoomFactor degrees
KStarsData *data = KStarsData::Instance();
double newDec = o->dec().Degrees() + 5730.0/m_vp.zoomFactor;
if ( newDec > 90.0 )
newDec = 90.0;
SkyPoint test( o->ra().Hours(), newDec );
if ( m_vp.useAltAz )
test.EquatorialToHorizontal( data->lst(), data->geo()->lat() );
Vector2f t = toScreenVec( &test );
float dx = t.x() - x;
float dy = y - t.y(); //backwards because QWidget Y-axis increases to the bottom
float north;
if ( dy ) {
north = atan2f( dx, dy )*180.0/dms::PI;
} else {
north = (dx > 0.0 ? -90.0 : 90.0);
}
return ( north + o->pa() );
}
QPointF Projector::toScreen(const SkyPoint* o, bool oRefract, bool* onVisibleHemisphere) const
{
return KSUtils::vecToPoint( toScreenVec(o, oRefract, onVisibleHemisphere) );
}
QVector< Vector2f > Projector::groundPoly(SkyPoint* labelpoint, bool *drawLabel) const
{
KStarsData *data = KStarsData::Instance();
QVector<Vector2f> ground;
static const QString horizonLabel = i18n("Horizon");
float marginLeft, marginRight, marginTop, marginBot;
SkyLabeler::Instance()->getMargins( horizonLabel, &marginLeft, &marginRight,
&marginTop, &marginBot );
//daz is 1/2 the width of the sky in degrees
double daz = 90.;
if ( m_vp.useAltAz ) {
daz = 0.5*m_vp.width*57.3/m_vp.zoomFactor; //center to edge, in degrees
if ( type() == SkyMap::Orthographic ) {
daz = daz * 1.4;
}
daz = qMin(90.0, daz);
}
double faz = m_vp.focus->az().Degrees();
double az1 = faz -daz;
double az2 = faz +daz;
bool allGround = true;
bool allSky = true;
double inc = 1.0;
//Add points along horizon
for(double az = az1; az <= az2 + inc; az += inc) {
SkyPoint p = pointAt(az,data);
bool visible = false;
Vector2f o = toScreenVec(&p, false, &visible);
if( visible ) {
ground.append( o );
//Set the label point if this point is onscreen
if ( labelpoint && o.x() < marginRight && o.y() > marginTop && o.y() < marginBot )
*labelpoint = p;
if ( o.y() > 0. ) allGround = false;
if ( o.y() < m_vp.height ) allSky = false;
}
}
if( allSky ) {
if( drawLabel)
*drawLabel = false;
return QVector<Vector2f>();
}
if( allGround ) {
ground.clear();
ground.append( Vector2f( -10., -10. ) );
ground.append( Vector2f( m_vp.width +10., -10. ) );
ground.append( Vector2f( m_vp.width +10., m_vp.height +10. ) );
ground.append( Vector2f( -10., m_vp.height +10. ) );
if( drawLabel)
*drawLabel = false;
return ground;
}
//In Gnomonic projection, or if sufficiently zoomed in, we can complete
//the ground polygon by simply adding offscreen points
//FIXME: not just gnomonic
if ( daz < 25.0 || type() == SkyMap::Gnomonic ) {
ground.append( Vector2f( m_vp.width + 10.f, ground.last().y() ) );
ground.append( Vector2f( m_vp.width + 10.f, m_vp.height + 10.f ) );
ground.append( Vector2f( -10.f, m_vp.height + 10.f ) );
ground.append( Vector2f( -10.f, ground.first().y() ) );
} else {
double r = m_vp.zoomFactor*radius();
double t1 = atan2( -1.*(ground.last().y() - 0.5*m_vp.height), ground.last().x() - 0.5*m_vp.width )/dms::DegToRad;
double t2 = t1 - 180.;
for ( double t=t1; t >= t2; t -= inc ) { //step along circumference
dms a( t );
double sa(0.), ca(0.);
a.SinCos( sa, ca );
ground.append( Vector2f( 0.5*m_vp.width + r*ca, 0.5*m_vp.height - r*sa) );
}
}
if( drawLabel)
*drawLabel = true;
return ground;
}
Vector2f Projector::clipLineVec( SkyPoint *p1, SkyPoint *p2 ) const
{
/* ASSUMES p1 was not clipped but p2 was.
* Return the QPoint that barely clips in the line twixt p1 and p2.
*/
//TODO: iteration = ceil( 0.5*log2( w^2 + h^2) )??
// also possibly rewrite this
// --hdevalence
int iteration = 15; // For "perfect" clipping:
// 2^interations should be >= max pixels/line
bool isVisible = true; // so we start at midpoint
SkyPoint mid;
Vector2f oMid;
double x, y, z, dx, dy, dz, ra, dec;
int newx, newy, oldx, oldy;
oldx = oldy = -10000; // any old value that is not the first omid
toXYZ( p1, &x, &y, &z );
// -jbb printf("\np1: %6.4f %6.4f %6.4f\n", x, y, z);
toXYZ( p2, &dx, &dy, &dz );
// -jbb printf("p2: %6.4f %6.4f %6.4f\n", dx, dy, dz);
dx -= x;
dy -= y;
dz -= z;
// Successive approximation to point on line that just clips.
while(iteration-- > 0) {
dx *= .5;
dy *= .5;
dz *= .5;
if ( ! isVisible ) { // move back toward visible p1
x -= dx;
y -= dy;
z -= dz;
}
else { // move out toward clipped p2
x += dx;
y += dy;
z += dz;
}
// -jbb printf(" : %6.4f %6.4f %6.4f\n", x, y, z);
// [x, y, z] => [ra, dec]
ra = atan2( y, x );
dec = asin( z / sqrt(x*x + y*y + z*z) );
mid = SkyPoint( ra * 12. / dms::PI, dec * 180. / dms::PI );
mid.EquatorialToHorizontal( m_data->lst(), m_data->geo()->lat() );
oMid = toScreenVec( &mid, false, &isVisible );
//AND the result with checkVisibility to clip things going below horizon
isVisible &= checkVisibility(&mid);
newx = (int) oMid.x();
newy = (int) oMid.y();
// -jbb printf("new x/y: %4d %4d", newx, newy);
if ( (oldx == newx) && (oldy == newy) ) {
break;
}
oldx = newx;
oldy = newy;
}
return oMid;
}
QVector< Vector2f > EquirectangularProjector::groundPoly(SkyPoint* labelpoint, bool* drawLabel) const
{
float x0 = m_vp.width/2.;
float y0 = m_vp.width/2.;
if( m_vp.useAltAz ) {
float dX = m_vp.zoomFactor*M_PI;
float dY = m_vp.zoomFactor*M_PI;
SkyPoint belowFocus;
belowFocus.setAz( m_vp.focus->az().Degrees() );
belowFocus.setAlt( 0.0 );
Vector2f obf = toScreenVec( &belowFocus, false );
//If the horizon is off the bottom edge of the screen,
//we can return immediately
if ( obf.y() > m_vp.height ) {
if( drawLabel )
*drawLabel = false;
return QVector<Vector2f>();
}
//We can also return if the horizon is off the top edge,
//as long as the ground poly is not being drawn
if ( obf.y() < 0. && m_vp.fillGround == false ) {
if( drawLabel )
*drawLabel = false;
return QVector<Vector2f>();
}
QVector<Vector2f> ground;
//Construct the ground polygon, which is a simple rectangle in this case
ground << Vector2f( x0 - dX, obf.y() )
<< Vector2f( x0 + dX, obf.y() )
<< Vector2f( x0 + dX, y0 + dY )
<< Vector2f( x0 - dX, y0 + dY );
if( labelpoint ) {
QPointF pLabel( x0 -dX -50., obf.y() );
KStarsData *data = KStarsData::Instance();
*labelpoint = fromScreen(pLabel, data->lst(), data->geo()->lat());
}
if( drawLabel )
*drawLabel = true;
return ground;
} else {
float dX = m_vp.zoomFactor*M_PI/2;
float dY = m_vp.zoomFactor*M_PI/2;
QVector<Vector2f> ground;
static const QString horizonLabel = i18n("Horizon");
float marginLeft, marginRight, marginTop, marginBot;
SkyLabeler::Instance()->getMargins( horizonLabel, &marginLeft, &marginRight,
&marginTop, &marginBot );
double daz = 90.;
double faz = m_vp.focus->az().Degrees();
double az1 = faz -daz;
double az2 = faz +daz;
bool allGround = true;
bool allSky = true;
double inc = 1.0;
//Add points along horizon
for(double az = az1; az <= az2 + inc; az += inc) {
SkyPoint p = pointAt(az);
bool visible = false;
Vector2f o = toScreenVec(&p, false, &visible);
if( visible ) {
ground.append( o );
//Set the label point if this point is onscreen
if ( labelpoint && o.x() < marginRight && o.y() > marginTop && o.y() < marginBot )
*labelpoint = p;
if ( o.y() > 0. ) allGround = false;
if ( o.y() < m_vp.height ) allSky = false;
}
}
if( allSky ) {
if( drawLabel)
*drawLabel = false;
return QVector<Vector2f>();
}
if( allGround ) {
ground.clear();
ground.append( Vector2f( x0 - dX, y0 - dY ) );
ground.append( Vector2f( x0 + dX, y0 - dY ) );
ground.append( Vector2f( x0 + dX, y0 + dY ) );
ground.append( Vector2f( x0 - dX, y0 + dY ) );
if( drawLabel)
*drawLabel = false;
return ground;
}
if( labelpoint ) {
QPointF pLabel( x0 -dX -50., ground.last().y() );
KStarsData *data = KStarsData::Instance();
*labelpoint = fromScreen(pLabel, data->lst(), data->geo()->lat());
}
if( drawLabel )
*drawLabel = true;
//Now add points along the ground
ground.append( Vector2f( x0 + dX, ground.last().y() ) );
ground.append( Vector2f( x0 + dX, y0 + dY ) );
ground.append( Vector2f( x0 - dX, y0 + dY ) );
ground.append( Vector2f( x0 - dX, ground.first().y() ) );
return ground;
}
}
