private static List <Mesh> CreateMeshesFromAiNode(Ai.Node aiNode, Ai.Scene aiScene, Object obj,
ref AxisAlignedBoundingBox objectAABB, ObjectSet objectSet, string texturesDirectoryPath)
{
var aiMeshes = aiNode.MeshIndices.Select(x => aiScene.Meshes[x]).Where(x => x.PrimitiveType == Ai.PrimitiveType.Triangle)
.OrderBy(x => x.VertexCount).ThenBy(x => x.FaceCount).ToList();
if (aiMeshes.Count == 0)
{
return(null);
}
var meshes = new List <Mesh>();
var transform = GetWorldTransform(aiNode);
int subIndex = 0;
for (int index = 0; index < aiMeshes.Count;)
{
int begin = index;
int end = index + 1;
int vertexCount = aiMeshes[index].VertexCount;
// Collect meshes till we hit the vertex count limit.
while (end < aiMeshes.Count)
{
if (vertexCount + aiMeshes[end].VertexCount > 32768)
{
break;
}
vertexCount += aiMeshes[end++].VertexCount;
}
var mesh = new Mesh {
Name = aiNode.Name
};
if (index != 0)
{
mesh.Name += "." + (++subIndex).ToString("D3");
}
var aabbMesh = new AxisAlignedBoundingBox();
int vertexOffset = 0;
for (int it = begin; it < end; it++) // we goin C++
{
var aiMesh = aiMeshes[it];
var aabbSubMesh = new AxisAlignedBoundingBox();
if (aiMesh.HasVertices)
{
if (mesh.Positions == null)
{
mesh.Positions = new Vector3[vertexCount];
}
for (int i = 0; i < aiMesh.VertexCount; i++)
{
var position = Vector3.Transform(aiMesh.Vertices[i].ToNumerics(), transform);
mesh.Positions[vertexOffset + i] = position;
aabbSubMesh.AddPoint(position);
}
}
if (aiMesh.HasNormals)
{
if (mesh.Normals == null)
{
mesh.Normals = new Vector3[vertexCount];
}
for (int i = 0; i < aiMesh.VertexCount; i++)
{
mesh.Normals[vertexOffset + i] = Vector3.Normalize(Vector3.TransformNormal(aiMesh.Normals[i].ToNumerics(), transform));
}
}
for (int i = 0; i < 4; i++)
{
if (!aiMesh.HasTextureCoords(i))
{
continue;
}
var texCoords = mesh.GetTexCoordsChannel(i);
if (texCoords == null)
{
texCoords = new Vector2[vertexCount];
mesh.SetTexCoordsChannel(i, texCoords);
}
for (int j = 0; j < aiMesh.VertexCount; j++)
{
var texCoord = new Vector2(
aiMesh.TextureCoordinateChannels[i][j].X,
aiMesh.TextureCoordinateChannels[i][j].Y);
texCoords[vertexOffset + j] = texCoord;
}
}
for (int i = 0; i < 2; i++)
{
if (!aiMesh.HasVertexColors(i))
{
continue;
}
var colors = mesh.GetColorsChannel(i);
if (colors == null)
{
colors = new Color[vertexCount];
for (int j = 0; j < vertexCount; j++)
{
colors[j] = Color.White;
}
mesh.SetColorsChannel(i, colors);
}
for (int j = 0; j < aiMesh.VertexCount; j++)
{
colors[vertexOffset + j] = aiMesh.VertexColorChannels[i][j].ToMML();
}
}
var subMesh = new SubMesh();
if (aiMesh.HasBones)
{
if (mesh.BoneWeights == null)
{
mesh.BoneWeights = new BoneWeight[vertexCount];
for (int i = 0; i < mesh.BoneWeights.Length; i++)
{
mesh.BoneWeights[i] = BoneWeight.Empty;
}
}
subMesh.BoneIndices = new ushort[aiMesh.BoneCount];
for (int i = 0; i < aiMesh.BoneCount; i++)
{
var aiBone = aiMesh.Bones[i];
int boneIndex = obj.Skin.Bones.FindIndex(
x => x.Name == aiBone.Name);
if (boneIndex == -1)
{
boneIndex = obj.Skin.Bones.Count;
var aiBoneNode = aiScene.RootNode.FindNode(aiBone.Name);
// This is not right, but I'm not sure how to transform the bind pose matrix
// while not having duplicate bones.
Matrix4x4.Invert(GetWorldTransform(aiBoneNode), out var inverseBindPoseMatrix);
obj.Skin.Bones.Add(new BoneInfo
{
Name = aiBoneNode.Name,
InverseBindPoseMatrix = inverseBindPoseMatrix
});
}
foreach (var boneWeight in aiBone.VertexWeights)
{
mesh.BoneWeights[vertexOffset + boneWeight.VertexID].AddWeight(i, boneWeight.Weight);
}
subMesh.BoneIndices[i] = ( ushort )boneIndex;
}
subMesh.BonesPerVertex = 4;
}
subMesh.Indices = aiMesh.Faces.Where(x => x.IndexCount == 3).SelectMany(x => x.Indices)
.Select(x => ( uint )(vertexOffset + x)).ToArray();
subMesh.PrimitiveType = PrimitiveType.Triangles;
subMesh.IndexFormat = IndexFormat.UInt16;
var aiMaterial = aiScene.Materials[aiMesh.MaterialIndex];
int materialIndex = obj.Materials.FindIndex(x => x.Name == aiMaterial.Name);
if (materialIndex == -1)
{
materialIndex = obj.Materials.Count;
obj.Materials.Add(CreateMaterialFromAiMaterial(aiMaterial, objectSet.TextureSet, texturesDirectoryPath));
}
subMesh.MaterialIndex = ( uint )materialIndex;
subMesh.BoundingSphere = aabbSubMesh.ToBoundingSphere();
subMesh.BoundingBox = aabbSubMesh.ToBoundingBox();
mesh.SubMeshes.Add(subMesh);
vertexOffset += aiMesh.VertexCount;
aabbMesh.Merge(aabbSubMesh);
}
if (mesh.BoneWeights != null)
{
for (int i = 0; i < mesh.BoneWeights.Length; i++)
{
mesh.BoneWeights[i].Validate();
}
}
mesh.GenerateTangents();
mesh.BoundingSphere = aabbMesh.ToBoundingSphere();
meshes.Add(mesh);
objectAABB.Merge(aabbMesh);
// Go to the next mesh
index = end;
}
return(meshes);
}