private static List <Triangle> CreateCap(Vector3 start, float radius, Vector3 normal, int steps, int precision)
{
var triangles = new List <Triangle>();
var end = start + normal * radius;
for (int i = 0; i < precision; ++i)
{
float t1 = ((i + 0) / (float)precision);
float t2 = ((i + 1) / (float)precision);
float radius1 = MathHelper.Lerp(0, radius, (float)Math.Sqrt(1f - (t1 * t1)));
float radius2 = MathHelper.Lerp(0, radius, (float)Math.Sqrt(1f - (t2 * t2)));
var pos1 = Vector3.Lerp(start, end, t1);
var pos2 = Vector3.Lerp(start, end, t2);
var startPoints = Disk.CreatePoints(pos1, normal, radius1, steps);
var endPoints = Disk.CreatePoints(pos2, normal, radius2, steps);
triangles.AddRange(GeometryHelper.ExtrudePoints(startPoints, endPoints));
}
return(triangles);
}
public static List <Part> Load(string[] lines)
{
// The global geometry
var positions = new List <Vector3>();
var normals = new List <Vector3>();
var texcoords = new List <Vector3>();
var vertices = new List <Vertex>();
var indices = new List <int>();
var mesh = new List <Part>();
var currentGroup = "";
var currentMaterial = "unknown";
// Parse all lines
foreach (var rawLine in lines)
{
// Skip the line if empty or is a comment
var line = rawLine.Trim();
if (line == "" || line.StartsWith("#"))
{
continue;
}
// Cut the line in different parts
var parts = line.Split(Separator, StringSplitOptions.RemoveEmptyEntries);
var type = parts[0];
// Vertex declaration
if (type.StartsWith("v"))
{
var vector = ParseVector3(parts);
if (type == "v")
{
positions.Add(vector);
}
else if (type == "vt")
{
texcoords.Add(vector);
}
else if (type == "vn")
{
normals.Add(vector);
}
}
else if (type == "f")
{
// Face declaration
if (currentGroup != "")
{
// Add the vertices to the group
vertices.Add(GetVertexFromF(parts[1], positions, texcoords, normals));
var index1 = vertices.Count - 1;
vertices.Add(GetVertexFromF(parts[2], positions, texcoords, normals));
var index2 = vertices.Count - 1;
vertices.Add(GetVertexFromF(parts[3], positions, texcoords, normals));
var index3 = vertices.Count - 1;
// Add the indices
indices.Add(index1);
indices.Add(index2);
indices.Add(index3);
// Handle quads
if (parts.Length > 4)
{
vertices.Add(GetVertexFromF(parts[4], positions, texcoords, normals));
var index4 = vertices.Count - 1;
indices.Add(index1);
indices.Add(index3);
indices.Add(index4);
}
}
}
else if (type == "g" || type == "o")
{
string name = string.Join("_", parts.Skip(1));
if (name != currentGroup)
{
if (currentGroup != "")
{
// Add the group to the mesh
var group = new Part()
{
Name = currentGroup, Material = currentMaterial
};
group.Vertices.AddRange(vertices);
group.Indices.AddRange(indices);
mesh.Add(group);
vertices.Clear();
indices.Clear();
}
currentGroup = name;
}
}
else if (type.StartsWith("usemtl"))
{
currentMaterial = (parts.Length > 1) ? parts[1] : "";
}
}
// Add the last group to the mesh
if (vertices.Any() && indices.Any())
{
var group = new Part()
{
Name = currentGroup, Material = currentMaterial
};
group.Vertices.AddRange(vertices);
group.Indices.AddRange(indices);
mesh.Add(group);
}
// Recalculate the normals if needed
if (!normals.Any())
{
// Recreate the normals
foreach (var part in mesh)
{
// Default normal for every different vertex
var normalsPerVertex = new Dictionary <Vector3, Vector3>();
foreach (var vertex in part.Vertices)
{
normalsPerVertex[vertex.Position] = new Vector3();
}
for (int i = 0; i < (part.Indices.Count - 2); i += 3)
{
// Compute the normal for each triangle
var i1 = part.Indices[i + 0];
var i2 = part.Indices[i + 1];
var i3 = part.Indices[i + 2];
var pos1 = part.Vertices[i1].Position;
var pos2 = part.Vertices[i2].Position;
var pos3 = part.Vertices[i3].Position;
var normal = GeometryHelper.GetFaceNormal(pos1, pos2, pos3);
// Add the normals
normalsPerVertex[pos1] = Vector3.Normalize(normalsPerVertex[pos1] + normal);
normalsPerVertex[pos2] = Vector3.Normalize(normalsPerVertex[pos2] + normal);
normalsPerVertex[pos3] = Vector3.Normalize(normalsPerVertex[pos3] + normal);
}
// Apply the new normals
for (int i = 0; i < part.Vertices.Count; ++i)
{
var vertex = part.Vertices[i];
vertex.Normal = normalsPerVertex[vertex.Position];
part.Vertices[i] = vertex;
}
}
}
// Return the mesh
return(mesh);
}
private static Vector3 GetNewPosition(IReadOnlyList <Triangle> allFaces, Vector3 vertex)
{
var faces = GetFacesForPoint(allFaces, vertex);
var edges = GetEdgesForPoint(allFaces, vertex);
if (faces.Count == edges.Count)
{
return(Barycentre(vertex, faces.Count,
GeometryHelper.Average(faces.Select(f => f.Center)),
GeometryHelper.Average(edges.Select(p => GeometryHelper.GetEdgeMiddle(vertex, p)))));
}
else
{
var avgMidEdges = GeometryHelper.Average(edges.Where(p => GetFacesForEdge(allFaces, vertex, p).Count == 1).Select(p => GeometryHelper.GetEdgeMiddle(vertex, p)));
return((vertex + avgMidEdges) / 2f);
}
}