public static IMeshSelection ExtrudeEdge(
this IMeshBuilder meshBuilder,
IMeshSelection edge,
Func <int, Vector3, Vector3> extrudeTranslationFunc)
{
Log.Trace("Will extrude edge {0}. Total vertices in mesh = {1}", edge, meshBuilder.Vertices.Count);
var lowerEdge = new MeshSelection(edge);
var extrudedEdge = new MeshSelection();
// Check if we're dealing with a closed selection loop.
var isClosed = lowerEdge.IsClosed;
if (isClosed)
{
Log.Trace("The edge has the same start and end point {0}", lowerEdge[0]);
}
// Extrude new vertices from the current source vertices.
for (int i = 0; i < lowerEdge.Count; i++)
{
var extrudeIdx = lowerEdge[i];
var p = meshBuilder.Vertices[extrudeIdx];
Log.Trace("extrudeIdx = {0}", extrudeIdx);
// TODO: Need to skip duplicate indexes when the start/end range is wrapped.
var translation = extrudeTranslationFunc(i, p);
var newVertexIdx = meshBuilder.AddVertex(p + translation);
extrudedEdge.Add(newVertexIdx);
// TODO: This currently assumes the normal won't be changed by the translation. Need fix
// support rotation as well.
meshBuilder.Normals.Add(meshBuilder.Normals[extrudeIdx]);
}
if (isClosed)
{
extrudedEdge.Add(extrudedEdge[0]);
}
Log.Trace("Building {0} quads", edge.Count);
Assert.AreEqual(lowerEdge.Count, extrudedEdge.Count, "Number of extruded indices should match the number of lower indices");
Log.Trace("lowerEdge = {0}", lowerEdge);
Log.Trace("extrudedEdge = {0}", extrudedEdge);
// Build quads between the start vertices and the extruded vertices, using the virtual
// selection which includes the closing vertex index.
for (int i = 0; i < lowerEdge.VirtualCount - 1; i++)
{
var bl = lowerEdge.GetAtVirtualIndex(i);
var tl = extrudedEdge.GetAtVirtualIndex(i);
var tr = extrudedEdge.GetAtVirtualIndex(i + 1);
var br = lowerEdge.GetAtVirtualIndex(i + 1);
Log.Trace("Building quad: verts=[{0},{1},{2},{3}], indices=[{4},{5},{6},{7}]",
meshBuilder.Vertices[bl],
meshBuilder.Vertices[tl],
meshBuilder.Vertices[tr],
meshBuilder.Vertices[br],
bl,
tl,
tr,
br);
meshBuilder.AddTriangle(bl, tl, br);
meshBuilder.AddTriangle(br, tl, tr);
}
return(extrudedEdge);
}
