/// <summary>
/// Create the Polygonal Faces for a new Tessellated Solid by extruding the given loop along the given normal.
/// </summary>
/// <param name="loops"></param>
/// <param name="extrudeDirection"></param>
/// <param name="extrusionHeight"></param>
/// <param name="midPlane"></param>
/// <returns></returns>
public static List <PolygonalFace> ExtrusionFacesFrom3DLoops(this IEnumerable <IEnumerable <Vector3> > loops, Vector3 extrudeDirection,
double extrusionHeight, bool midPlane = false)
{
// for consistency with adding the extrusionHeight to the base plane, negate if it comes in negative
if (extrusionHeight < 0)
{
extrusionHeight = -extrusionHeight;
extrudeDirection = -1 * extrudeDirection;
}
// find transform to the XY plane and store the backTransform (the transform back to the original)
var transform = MiscFunctions.TransformToXYPlane(extrudeDirection, out var backTransform);
// make paths, the 2D polygons represening the 3D loops
var paths = loops.Select(loop => loop.ProjectTo2DCoordinates(transform, 0, true));
// the basePlaneDistance defines the plane closer to the origin. we can get this from the any input coordinate
var basePlaneDistance = extrudeDirection.Dot(loops.First().First());
if (midPlane)
{
basePlaneDistance -= extrusionHeight / 2.0;
}
var polygons = paths.CreateShallowPolygonTrees(false);
return(polygons.SelectMany(polygon => Extrude.ExtrusionFacesFrom2DPolygons(polygon,
extrudeDirection, basePlaneDistance, extrusionHeight)).ToList());
}
/// <summary>
/// Create the triangular faces of an extruded solid from 2D paths.
/// </summary>
/// <param name="paths">The paths.</param>
/// <param name="basePlaneNormal">The base plane normal.</param>
/// <param name="basePlaneDistance">The base plane distance.</param>
/// <param name="extrusionHeight">Height of the extrusion.</param>
/// <returns>List<PolygonalFace>.</returns>
public static List <PolygonalFace> ExtrusionFacesFrom2DPolygons(this IEnumerable <IEnumerable <Vector2> > paths, Vector3 basePlaneNormal,
double basePlaneDistance, double extrusionHeight)
{
var polygons = paths.CreateShallowPolygonTrees(false);
return(polygons.SelectMany(polygon => Extrude.ExtrusionFacesFrom2DPolygons(polygon,
basePlaneNormal, basePlaneDistance, extrusionHeight)).ToList());
}
