/// <summary>
/// Creates a new instance of a complex lens using a definition of
/// elements.
/// </summary>
/// <remarks>
/// The first and last surfaces have to be spherical. TODO: this is
/// needed only for simpler sampling. In general planar surfaces or
/// stops could be sampled too.
/// </remarks>
/// <param name="surfaceDefs">List of definitions of spherical or
/// planar element surfaces or stops. Ordered from front to back.
/// Must not be empty or null.
/// </param>
/// <param name="mediumRefractiveIndex">Index of refraction of medium
/// outside the lens. It is assumed there is one medium on the scene
/// side, senzor side and inside the lens.</param>
/// <returns>The created complex lens instance.</returns>
public static ComplexLens Create(
IList<SphericalElementSurfaceDefinition> surfaceDefs,
double mediumRefractiveIndex,
double scale)
{
var surfaces = new List<ElementSurface>();
var surfaceDefsReverse = surfaceDefs.Reverse().ToList();
// scale the lens if needed
if (Math.Abs(scale - 1.0) > epsilon)
{
surfaceDefsReverse = surfaceDefsReverse.Select(surface => surface.Scale(scale)).ToList();
}
// thickness of the whole lens (from front to back apex)
// (without the distance to the senzor - backmost surface def.)
double lensThickness = surfaceDefsReverse.Skip(1).Sum(def => def.Thickness);
double elementBasePlaneShiftZ = lensThickness;
double lastCapHeight = 0;
double capHeight = 0;
// definition list is ordered from front to back, working list
// must be ordered from back to front, so a conversion has to be
// performed
int defIndex = 0;
foreach (var definition in surfaceDefsReverse)
{
if (defIndex > 0)
{
elementBasePlaneShiftZ -= definition.Thickness;
}
ElementSurface surface = new ElementSurface();
surface.ApertureRadius = 0.5 * definition.ApertureDiameter;
if (defIndex + 1 < surfaceDefsReverse.Count)
{
surface.NextRefractiveIndex = surfaceDefsReverse[defIndex + 1].NextRefractiveIndex;
}
else
{
surface.NextRefractiveIndex = mediumRefractiveIndex;
}
if (definition.CurvatureRadius.HasValue)
{
// spherical surface
double radius = definition.CurvatureRadius.Value;
// convexity reverses when converting from front-to-back
// back-to-front ordering
surface.Convex = radius < 0;
Sphere sphere = new Sphere()
{
Radius = Math.Abs(radius)
};
sphere.Center = Math.Sign(radius) *
sphere.GetCapCenter(surface.ApertureRadius, Vector3d.UnitZ);
capHeight = Math.Sign(radius) * sphere.GetCapHeight(sphere.Radius, surface.ApertureRadius);
elementBasePlaneShiftZ -= lastCapHeight - capHeight;
sphere.Center += new Vector3d(0, 0, elementBasePlaneShiftZ);
surface.Surface = sphere;
surface.SurfaceNormalField = sphere;
}
else
{
// planar surface
// both media are the same -> circular stop
// else -> planar element surface
surface.NextRefractiveIndex = definition.NextRefractiveIndex;
surface.Convex = true;
capHeight = 0;
elementBasePlaneShiftZ -= lastCapHeight - capHeight;
Circle circle = new Circle()
{
Radius = 0.5 * definition.ApertureDiameter,
Z = elementBasePlaneShiftZ,
};
surface.Surface = circle;
surface.SurfaceNormalField = circle;
}
lastCapHeight = capHeight;
surfaces.Add(surface);
defIndex++;
}
//DEBUG
//foreach (var surface in surfaces)
//{
// Console.WriteLine("{0}, {1}, {2}", surface.ApertureRadius,
// surface.Convex, surface.NextRefractiveIndex);
//}
ComplexLens lens = new ComplexLens(surfaces)
{
MediumRefractiveIndex = mediumRefractiveIndex
};
return lens;
}
