public WavefrontObj(Stream stream)
{
Obj? obj = null;
Span <char> buffer = stackalloc char[1024];
using var reader = new StreamReader(stream);
var remaining = buffer.Slice(0, reader.Read(buffer));
var eof = false;
while (remaining.Length > 0)
{
var index = 0;
while ((index = remaining.IndexOf('\n')) >= 0 || (remaining.Length > 0 && eof))
{
if (index <= 0)
{
index = remaining.Length;
}
var line = remaining.Slice(0, index);
remaining = remaining.Slice(Math.Min(remaining.Length, index + 1));
while (line.Length > 0 && char.IsWhiteSpace(line[0]))
{
line = line.Slice(1);
}
while (line.Length > 0 && char.IsWhiteSpace(line[line.Length - 1]))
{
line = line.Slice(0, line.Length - 1);
}
if (line.Length <= 0)
{
continue;
}
// obj
if (line[0] == 'o' && line.Length > 3)
{
obj = new Obj(line.Slice(2).ToString());
Objects.Add(obj.Name, obj);
}
else if (line[0] == 'v' && line.Length > 3)
{
// normal
if (line[1] == 'n')
{
if (Calc.ParseVector3(line.Slice(3), ' ', out var normal))
{
Normals.Add(normal);
}
}
// tex-coord
else if (line[1] == 't')
{
if (Calc.ParseVector2(line.Slice(3), ' ', out var texcoord))
{
Texcoords.Add(texcoord);
}
}
// position
else
{
if (Calc.ParseVector3(line.Slice(2), ' ', out var position))
{
Positions.Add(position);
}
}
}
else if (line[0] == 'f' && line.Length > 3)
{
if (obj == null)
{
obj = new Obj("Unnamed");
Objects.Add(obj.Name, obj);
}
var face = new Face {
VertexIndex = obj.Vertices.Count
};
var data = line.Slice(2);
var next = data;
while ((next = NextSplit(ref data, ' ')).Length > 0)
{
var vertex = new Vertex();
var i = 0;
while (next.Length > 0)
{
var sub = NextSplit(ref next, '/');
if (sub.Length > 0)
{
if (i == 0)
{
vertex.PositionIndex = int.Parse(sub) - 1;
}
else if (i == 1)
{
vertex.NormalIndex = int.Parse(sub) - 1;
}
else if (i == 2)
{
vertex.TexcoordIndex = int.Parse(sub) - 1;
}
}
i++;
}
obj.Vertices.Add(vertex);
face.VertexCount++;
}
obj.Faces.Add(face);
}
}
// shift memory back & read more
remaining.CopyTo(buffer);
var offset = buffer.Slice(remaining.Length);
var read = reader.Read(offset);
// how much is left to read
remaining = buffer.Slice(0, remaining.Length + read);
// reached the end
if (read < offset.Length)
{
eof = true;
}
}
}
protected override void CreateGeometry()
{
base.CreateGeometry();
if (!GenerateGeometry)
{
return;
}
//create buffer descriptions
var vDesc = new BufferDesc()
{
Width = (uint)Positions.Count, Format = Format.Float3, Type = BufferType.Input
};
var nDesc = new BufferDesc()
{
Width = (uint)Normals.Count, Format = Format.Float3, Type = BufferType.Input
};
var tcDesc = new BufferDesc()
{
Width = (uint)Texcoords.Count, Format = Format.Float2, Type = BufferType.Input
};
// Create the buffers to hold our geometry data
var vBuffer = new OptixBuffer(Context, vDesc);
var nBuffer = new OptixBuffer(Context, nDesc);
var tcBuffer = new OptixBuffer(Context, tcDesc);
vBuffer.SetData <Vector3>(Positions.ToArray());
nBuffer.SetData <Vector3>(Normals.ToArray());
tcBuffer.SetData <Vector2>(Texcoords.ToArray());
List <GeometryInstance> instances = new List <GeometryInstance>();
foreach (ObjGroup group in Groups)
{
//empty group
if (group.VIndices.Count == 0 && group.NIndices.Count == 0 && group.TIndices.Count == 0)
{
continue;
}
//ValidateGroup( group );
var normalsUseVIndices = GenerateNormals && group.NIndices.Count == 0 && Normals.Count > 0;
if (normalsUseVIndices)
{
Debug.Assert(Normals.Count == Positions.Count);
}
var numNormIndices = normalsUseVIndices ? group.VIndices.Count : group.NIndices.Count;
var viDesc = new BufferDesc {
Width = (uint)group.VIndices.Count, Format = Format.Int3, Type = BufferType.Input
};
var niDesc = new BufferDesc {
Width = (uint)numNormIndices, Format = Format.Int3, Type = BufferType.Input
};
var tiDesc = new BufferDesc {
Width = (uint)group.TIndices.Count, Format = Format.Int3, Type = BufferType.Input
};
var viBuffer = new OptixBuffer(Context, viDesc);
var niBuffer = new OptixBuffer(Context, niDesc);
var tiBuffer = new OptixBuffer(Context, tiDesc);
viBuffer.SetData(group.VIndices.ToArray());
//if normals weren't in the obj and we genereated them, use the vertex indices
niBuffer.SetData(normalsUseVIndices ? group.VIndices.ToArray() : group.NIndices.ToArray());
tiBuffer.SetData(group.TIndices.ToArray());
//create a geometry node and set the buffers
var geometry = new Geometry(Context);
geometry.IntersectionProgram = new OptixProgram(Context, IntersecitonProgPath, IntersecitonProgName);
geometry.BoundingBoxProgram = new OptixProgram(Context, BoundingBoxProgPath, BoundingBoxProgName);
geometry.PrimitiveCount = (uint)group.VIndices.Count;
geometry["vertex_buffer"].Set(vBuffer);
geometry["normal_buffer"].Set(nBuffer);
geometry["texcoord_buffer"].Set(tcBuffer);
geometry["vindex_buffer"].Set(viBuffer);
geometry["nindex_buffer"].Set(niBuffer);
geometry["tindex_buffer"].Set(tiBuffer);
//create a geometry instance
GeometryInstance instance = new GeometryInstance(Context);
instance.Geometry = geometry;
instance.AddMaterial(_materialResolveFunc(group.mtrl) ?? DefaultMaterial);
if (group.mtrl != null)
{
ObjMaterial mtrl = mMtrls[group.mtrl];
instance["diffuse_color"].SetFloat3(ref mtrl.Kd);
instance["emission_color"].SetFloat3(ref mtrl.Ke);
}
else
{
instance["diffuse_color"].Set(1.0f, 1.0f, 1.0f);
}
instances.Add(instance);
}
//create an acceleration structure for the geometry
var accel = new Acceleration(Context, Builder, Traverser);
if (Builder == AccelBuilder.Sbvh || Builder == AccelBuilder.TriangleKdTree)
{
accel.VertexBufferName = "vertex_buffer";
accel.IndexBufferName = "vindex_buffer";
}
//now attach the instance and accel to the geometry group
GeoGroup.Acceleration = accel;
GeoGroup.AddChildren(instances);
}
