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fix: Model collision issues with more complex meshes #3036

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fix: Model collision issues with more complex meshes #3036

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2 changes: 1 addition & 1 deletion sources/engine/Stride.BepuPhysics/Stride.BepuPhysics/Systems/CollidableGizmo.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -112,7 +112,7 @@ private void PrepareModels()
var bepuShapeCacheSys = _services.GetOrCreate<ShapeCacheSystem>();
var graphicsDevice = _services.GetSafeServiceAs<IGraphicsDeviceService>().GraphicsDevice;

if (_component.Collider is MeshCollider meshCollider && (meshCollider.Model.Meshes.Count == 0 || meshCollider.Model == null!/*May be null in editor*/))
if (_component.Collider is MeshCollider meshCollider && (meshCollider.Model == null!/*May be null in editor*/ || meshCollider.Model.Meshes.Count == 0))
{
// It looks like meshes take some time before being filled in by the editor ... ?
// Schedule it for later
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102 changes: 86 additions & 16 deletions sources/engine/Stride.BepuPhysics/Stride.BepuPhysics/Systems/ShapeCacheSystem.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -139,6 +139,8 @@ private static void ExtractHull(DecomposedHulls hullDesc, out VertexPosition3[]

internal static unsafe BepuUtilities.Memory.Buffer<Triangle> ExtractBepuMesh(Model model, IServiceRegistry services, BufferPool pool)
{
var nodeTransforms = ExtractNodeTransforms(model);

int totalIndices = 0;
foreach (var meshData in model.Meshes)
{
Expand All @@ -148,13 +150,24 @@ internal static unsafe BepuUtilities.Memory.Buffer<Triangle> ExtractBepuMesh(Mod
pool.Take<Triangle>(totalIndices / 3, out var triangles);
var bepuTriangles = triangles.As<Vector3>();
var spanLeft = new Span<Vector3>(bepuTriangles.Memory, bepuTriangles.Length);
foreach (var mesh in model.Meshes)
foreach (var meshData in model.Meshes)
{
mesh.Draw.IndexBuffer.AsReadable(services, out var indexHelper, out int indexCount);
mesh.Draw.VertexBuffers[0].AsReadable(services, out var vertexHelper, out int vertexCount);
meshData.Draw.IndexBuffer.AsReadable(services, out var indexHelper, out int indexCount);
meshData.Draw.VertexBuffers[0].AsReadable(services, out var vertexHelper, out int vertexCount);

var copyJob = new VertexBufferHelper.CopyAsTriangleList { IndexBufferHelper = indexHelper };
vertexHelper.Read<PositionSemantic, Vector3, VertexBufferHelper.CopyAsTriangleList>(spanLeft[..indexCount], copyJob);
var vertSlice = spanLeft[..indexCount];
vertexHelper.Read<PositionSemantic, Vector3, VertexBufferHelper.CopyAsTriangleList>(vertSlice, copyJob);

if (nodeTransforms != null)
{
for (int i = 0; i < vertSlice.Length; i++)
{
Matrix posMatrix = Matrix.Translation(vertSlice[i]);
Matrix.Multiply(ref posMatrix, ref nodeTransforms[meshData.NodeIndex], out var finalMatrix);
vertSlice[i] = finalMatrix.TranslationVector;
}
}

spanLeft = spanLeft[indexCount..];
}
Expand All @@ -164,30 +177,87 @@ internal static unsafe BepuUtilities.Memory.Buffer<Triangle> ExtractBepuMesh(Mod

private static void ExtractMeshBuffers(Model model, IServiceRegistry services, out VertexPosition3[] vertices, out int[] indices)
{
int totalVertices = 0, totalIndices = 0;
var nodeTransforms = ExtractNodeTransforms(model);

int totalVerts = 0, totalIndices = 0;
foreach (var meshData in model.Meshes)
{
totalVertices += meshData.Draw.VertexBuffers[0].Count;
totalVerts += meshData.Draw.VertexBuffers[0].Count;
totalIndices += meshData.Draw.IndexBuffer.Count;
}

vertices = new VertexPosition3[totalVertices];
indices = new int[totalIndices];
var combinedVerts = new VertexPosition3[totalVerts];
var combinedIndices = new int[totalIndices];
var verticesLeft = MemoryMarshal.Cast<VertexPosition3, Vector3>(combinedVerts.AsSpan());
var indicesLeft = combinedIndices.AsSpan();

var verticesLeft = MemoryMarshal.Cast<VertexPosition3, Vector3>(vertices.AsSpan());
var indicesLeft = indices.AsSpan();

foreach (var mesh in model.Meshes)
int indexOffset = 0;
foreach (var meshData in model.Meshes)
{
mesh.Draw.IndexBuffer.AsReadable(services, out var indexHelper, out int indexCount);
mesh.Draw.VertexBuffers[0].AsReadable(services, out var vertexHelper, out int vertexCount);
meshData.Draw.VertexBuffers[0].AsReadable(services, out var vertexHelper, out var vertexCount);
meshData.Draw.IndexBuffer.AsReadable(services, out var indexHelper, out var indexCount);

var vertSlice = verticesLeft[..vertexCount];
vertexHelper.Copy<PositionSemantic, Vector3>(vertSlice);

if (nodeTransforms != null)
{
for (int i = 0; i < vertSlice.Length; i++)
{
Matrix posMatrix = Matrix.Translation(vertSlice[i]);
Matrix.Multiply(ref posMatrix, ref nodeTransforms[meshData.NodeIndex], out var finalMatrix);
vertSlice[i] = finalMatrix.TranslationVector;
}
}

vertexHelper.Copy<PositionSemantic, Vector3>(verticesLeft[..vertexCount]);
indexHelper.CopyTo(indicesLeft[..indexCount]);
var indicesForSlice = indicesLeft[..indexCount];
indexHelper.CopyTo(indicesForSlice);
for (int i = 0; i < indicesForSlice.Length; i++)
indicesForSlice[i] += indexOffset;
indexOffset += vertexCount;

verticesLeft = verticesLeft[vertexCount..];
indicesLeft = indicesLeft[indexCount..];
}

vertices = combinedVerts;
indices = combinedIndices;
}

private static Matrix[]? ExtractNodeTransforms(Model model)
{
Matrix[]? nodeTransforms = null;
if (model.Skeleton == null)
return nodeTransforms;

var nodesLength = model.Skeleton.Nodes.Length;
nodeTransforms = new Matrix[nodesLength];
nodeTransforms[0] = Matrix.Identity;
for (var i = 0; i < nodesLength; i++)
{
var node = model.Skeleton.Nodes[i];
Matrix.Transformation(ref node.Transform.Scale, ref node.Transform.Rotation, ref node.Transform.Position, out var localMatrix);

Matrix worldMatrix;
if (node.ParentIndex != -1)
{
if (node.ParentIndex >= i)
throw new InvalidOperationException("Skeleton nodes are not sorted");
var nodeTransform = nodeTransforms[node.ParentIndex];
Matrix.Multiply(ref localMatrix, ref nodeTransform, out worldMatrix);
}
else
{
worldMatrix = localMatrix;
}

if (i != 0)
{
nodeTransforms[i] = worldMatrix;
}
}

return nodeTransforms;
}

/// <summary>
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26 changes: 16 additions & 10 deletions sources/engine/Stride.Physics/Shapes/StaticMeshColliderShape.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -158,28 +158,34 @@ static SharedMeshData BuildAndShareMeshes(Model model, IServiceRegistry services
var combinedIndices = new int[totalIndices];
var verticesLeft = combinedVerts.AsSpan();
var indicesLeft = combinedIndices.AsSpan();


int indexOffset = 0;
foreach (var meshData in model.Meshes)
{
meshData.Draw.VertexBuffers[0].AsReadable(services, out var vertexHelper, out var vertexCount);
meshData.Draw.IndexBuffer.AsReadable(services, out var indexHelper, out var indexCount);

var sliceForTheseVertices = verticesLeft[..vertexCount];
vertexHelper.Copy<PositionSemantic, Vector3>(sliceForTheseVertices);
indexHelper.CopyTo(indicesLeft[..indexCount]);

verticesLeft = verticesLeft[vertexCount..];
indicesLeft = indicesLeft[indexCount..];
var vertSlice = verticesLeft[..vertexCount];
vertexHelper.Copy<PositionSemantic, Vector3>(vertSlice);

if (nodeTransforms != null)
{
for (int i = 0; i < sliceForTheseVertices.Length; i++)
for (int i = 0; i < vertSlice.Length; i++)
{
Matrix posMatrix = Matrix.Translation(sliceForTheseVertices[i]);
Matrix posMatrix = Matrix.Translation(vertSlice[i]);
Matrix.Multiply(ref posMatrix, ref nodeTransforms[meshData.NodeIndex], out var finalMatrix);
sliceForTheseVertices[i] = finalMatrix.TranslationVector;
vertSlice[i] = finalMatrix.TranslationVector;
}
}

var indicesForSlice = indicesLeft[..indexCount];
indexHelper.CopyTo(indicesForSlice);
for (int i = 0; i < indicesForSlice.Length; i++)
indicesForSlice[i] += indexOffset;
indexOffset += vertexCount;

verticesLeft = verticesLeft[vertexCount..];
indicesLeft = indicesLeft[indexCount..];
}

if (string.IsNullOrWhiteSpace(modelUrl))
Expand Down
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