/// <summary>
/// Splits the mesh into submeshes that use <paramref name="maxVertexCount"/> or less vertices.
/// </summary>
/// <param name="mesh"></param>
/// <param name="maxVertexCount"></param>
/// <returns></returns>
public static List <Assimp.Mesh> SplitMeshByVertexCount(Assimp.Mesh mesh, int maxVertexCount)
{
if (mesh.VertexCount <= maxVertexCount)
{
return new List <Assimp.Mesh> {
mesh
}
}
;
var vertexWeights = mesh.HasBones ? mesh.GetVertexWeights() : null;
var remainingFaces = mesh.Faces.ToList();
var subMeshes = new List <Assimp.Mesh>();
while (remainingFaces.Count > 0)
{
// Build submesh
var subMesh = new Assimp.Mesh()
{
MaterialIndex = mesh.MaterialIndex,
//MorphMethod = mesh.MorphMethod,
Name = mesh.Name + $"_submesh{subMeshes.Count}",
PrimitiveType = mesh.PrimitiveType,
};
var processedFaces = new List <Face>();
var vertexCache = new List <Vertex>();
// Get faces that fit inside the new mesh
foreach (var face in remainingFaces)
{
var newVertices = new List <Vertex>();
var newFace = new Face();
foreach (var i in face.Indices)
{
var cacheIndex = FindVertexCacheIndex(mesh, i, vertexWeights, vertexCache, out var vertex);
if (cacheIndex == -1)
{
// This vertex is new
cacheIndex = vertexCache.Count + newVertices.Count;
newVertices.Add(vertex);
}
newFace.Indices.Add(cacheIndex);
}
if (vertexCache.Count + newVertices.Count > maxVertexCount)
{
// Doesn't fit
continue;
}
// It does fit ＼(^o^)／
subMesh.Faces.Add(newFace);
processedFaces.Add(face);
foreach (var vertex in newVertices)
{
vertexCache.Add(vertex);
}
Debug.Assert(vertexCache.Count <= maxVertexCount);
if (vertexCache.Count == maxVertexCount)
{
// We're done for sure
break;
}
}
// Remove the faces we processed from the remaining list
foreach (var face in processedFaces)
{
remainingFaces.Remove(face);
}
PopulateSubMeshVertexData(mesh, subMesh, vertexCache);
#if DEBUG
CheckIfAllVerticesHaveWeights(subMesh);
#endif
subMeshes.Add(subMesh);
}
return(subMeshes);
}
/// <summary>
/// Splits the mesh into submeshes that use <paramref name="maxBoneCount"/> or less bones.
/// </summary>
/// <param name="scene"></param>
/// <param name="mesh"></param>
/// <param name="maxBoneCount"></param>
/// <returns></returns>
public static List <Assimp.Mesh> SplitMeshByBoneCount(Assimp.Mesh mesh, int maxBoneCount)
{
if (mesh.BoneCount <= maxBoneCount)
{
return new List <Assimp.Mesh> {
mesh
}
}
;
var vertexWeights = mesh.GetVertexWeights();
var subMeshes = new List <Assimp.Mesh>();
var remainingFaces = mesh.Faces.ToList();
while (remainingFaces.Count > 0)
{
var usedBones = new HashSet <Assimp.Bone>();
var faces = new List <Face>();
// Get faces that fit inside the new mesh
foreach (var face in remainingFaces)
{
var faceUsedBones = face.Indices.SelectMany(y => vertexWeights[y].Select(z => z.Item1)).ToList();
var faceUniqueUsedBoneCount = faceUsedBones.Count(x => !usedBones.Contains(x));
if ((usedBones.Count + faceUniqueUsedBoneCount) > maxBoneCount)
{
// Skip
continue;
}
// It does fit ＼(^o^)／
faces.Add(face);
foreach (var node in faceUsedBones)
{
usedBones.Add(node);
}
Debug.Assert(usedBones.Count <= maxBoneCount);
}
if (faces.Count == 0)
{
if (remainingFaces.All(x => x.Indices.SelectMany(y => vertexWeights[y].Select(z => z.Item1)).Count() > maxBoneCount))
{
// Need to reduce weights per face
Debug.Assert(false); // would need averaging..
}
}
// Remove the faces we claimed from the pool
foreach (var face in faces)
{
remainingFaces.Remove(face);
}
// Build submesh
var subMesh = new Assimp.Mesh()
{
MaterialIndex = mesh.MaterialIndex,
//MorphMethod = mesh.MorphMethod,
Name = mesh.Name + $"_submesh{subMeshes.Count}",
PrimitiveType = mesh.PrimitiveType,
};
var vertexCache = new List <Vertex>();
foreach (var face in faces)
{
var newFace = new Face();
foreach (var index in face.Indices)
{
var cacheIndex = FindVertexCacheIndex(mesh, index, vertexWeights, vertexCache, out var vertex);
if (cacheIndex == -1)
{
// This vertex is new
#if DEBUG
for (int i = 0; i < vertex.Weights.Count; i++)
{
Debug.Assert(usedBones.Contains(vertex.Weights[i].Item1));
}
#endif
cacheIndex = vertexCache.Count;
vertexCache.Add(vertex);
}
newFace.Indices.Add(cacheIndex);
}
subMesh.Faces.Add(newFace);
}
PopulateSubMeshVertexData(mesh, subMesh, vertexCache);
#if DEBUG
CheckIfAllVerticesHaveWeights(subMesh);
#endif
subMeshes.Add(subMesh);
}
return(subMeshes);
}