Skip to content

Fix incorrect DispatchMesh group calculation in D3D12DynamicLOD sample #942

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
jenatali merged 1 commit into from
Jan 13, 2026
Merged

Fix incorrect DispatchMesh group calculation in D3D12DynamicLOD sample #942

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 6 additions & 4 deletions Samples/Desktop/D3D12MeshShaders/src/DynamicLOD/D3D12DynamicLOD.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -606,17 +606,19 @@ void D3D12DynamicLOD::PopulateCommandList()
m_commandList->SetGraphicsRootDescriptorTable(2, m_srvHeap->GetGPUDescriptorHandleForHeapStart());
m_commandList->SetGraphicsRootShaderResourceView(3, m_instanceBuffer->GetGPUVirtualAddress());

uint32_t dispatchCount = DivRoundUp(m_instanceCount, c_maxGroupDispatchCount);
uint32_t instancesPerDispatch = c_maxGroupDispatchCount * AS_GROUP_SIZE;
uint32_t dispatchCount = DivRoundUp(m_instanceCount, instancesPerDispatch);

for (uint32_t i = 0; i < dispatchCount; ++i)
{
uint32_t offset = dispatchCount * i;
uint32_t count = min(m_instanceCount - offset, c_maxGroupDispatchCount);
uint32_t offset = instancesPerDispatch * i;
uint32_t count = min(m_instanceCount - offset, instancesPerDispatch);

m_commandList->SetGraphicsRoot32BitConstant(1, offset, 0);
m_commandList->SetGraphicsRoot32BitConstant(1, count, 1);

m_commandList->DispatchMesh(count, 1, 1);
uint32_t groupCount = DivRoundUp(count, AS_GROUP_SIZE);
m_commandList->DispatchMesh(groupCount, 1, 1);
}

// Indicate that the back buffer will now be used to present.
Expand Down
4 changes: 2 additions & 2 deletions Samples/Desktop/D3D12MeshShaders/src/DynamicLOD/MeshletAS.hlsl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -47,10 +47,10 @@ void main(uint dtid : SV_DispatchThreadID, uint gtid : SV_GroupThreadID, uint gi
uint lodLevel = MAX_LOD_LEVELS; // LOD level of this thread's instance
uint lodOffset = 0; // Offset into its LOD-level instance list

uint instanceIndex = DrawParams.InstanceOffset + dtid;
uint instanceIndex = dtid;
if (instanceIndex < DrawParams.InstanceCount)
{
Instance instance = Instances[instanceIndex];
Instance instance = Instances[DrawParams.InstanceOffset + instanceIndex];

if (IsVisible(instance.BoundingSphere))
{
Expand Down