private CurveItem GetSunCurve(TerrainPatch patch, Point pt, math.Vector3d sun, Color color)
{
patch.FillPointsAndMatrices(LunarHorizon.Terrain);
patch.GetAzEl(sun, pt.X, pt.Y, out float az_rad, out float el_rad);
{
var horizon = patch.GetHorizon(pt.Y, pt.X);
var frac = (byte)(255f * horizon.SunFraction2(az_rad * 180f / 3.141592653589f, el_rad * 180f / 3.141592653589f));
Console.WriteLine($"patch.id={patch.Id} pt=[{pt.X},{pt.Y}] Sun frac={frac}");
}
var az_deg = az_rad * 180f / 3.141592565589f;
var el_deg = el_rad * 180f / 3.141592565589f;
const int count = 12;
const double radius = 32d / 60d;
var points = new PointPairList();
for (var i = 0; i <= count; i++)
{
var ang = i * 2d * Math.PI / count;
points.Add(az_deg + radius * Math.Cos(ang), el_deg + radius * Math.Sin(ang));
}
return(new LineItem(null, points, color, SymbolType.None));
}