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Fix: Revert changes in Mesh to Volume node and modifier to Blender 3.6

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This brings back the `Fill Volume` and `Exterior Bandwidth` inputs in
the Mesh to Volume node and modifier. Those existed in Blender 3.5 but
were removed in 700d168a5c because the way they were
implemented did not use the openvdb api in the right way.

While it's rare that people turned off the `Fill Volume` option, the
exterior bandwidth was used more and can have significant impact on
the result. Furthermore, there is no clear replacement for the
functionality.

Therefore, we decided to roll back the changes in 3.6 to avoid breaking
compatibility. We intend to keep the changes in 4.0 for now, but need
to work on a more clear short term replacement for the removed
functionality.

Pull Request: https://projects.blender.org/blender/blender/pulls/109297
This commit is contained in:
Jacques Lucke
2023-06-23 20:12:17 +02:00
committed by Hans Goudey
parent 16739b92ca
commit 537fdbbfa2
6 changed files with 104 additions and 30 deletions
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70
source/blender/geometry/intern/mesh_to_volume.cc
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@@ -97,19 +97,18 @@ float volume_compute_voxel_size(const Depsgraph *depsgraph,
const float diagonal = math::distance(math::transform_point(transform, bb_max),
math::transform_point(transform, bb_min));
/* To get the approximate size per voxel, first subtract the exterior band from the requested
* voxel amount, then divide the diagonal with this value if it's bigger than 1. */
const float voxel_size =
(diagonal / std::max(1.0f, float(res.settings.voxel_amount) - 2.0f * exterior_band_width));
/* Return the simplified voxel size. */
return voxel_size / volume_simplify;
const float approximate_volume_side_length = diagonal + exterior_band_width * 2.0f;
const float voxel_size = approximate_volume_side_length / res.settings.voxel_amount /
volume_simplify;
return voxel_size;
}
static openvdb::FloatGrid::Ptr mesh_to_fog_volume_grid(
const Mesh *mesh,
const float4x4 &mesh_to_volume_space_transform,
const float voxel_size,
const bool fill_volume,
const float exterior_band_width,
const float interior_band_width,
const float density)
{
@@ -123,21 +122,27 @@ static openvdb::FloatGrid::Ptr mesh_to_fog_volume_grid(
mesh_to_index_space_transform.location() -= 0.5f;
OpenVDBMeshAdapter mesh_adapter{*mesh, mesh_to_index_space_transform};
const float interior = std::max(1.0f, interior_band_width / voxel_size);
openvdb::math::Transform::Ptr transform = openvdb::math::Transform::createLinearTransform(
voxel_size);
openvdb::FloatGrid::Ptr new_grid = openvdb::tools::meshToVolume<openvdb::FloatGrid>(
mesh_adapter, *transform, 1.0f, interior);
/* Convert the bandwidths from object in index space. */
const float exterior = MAX2(0.001f, exterior_band_width / voxel_size);
const float interior = MAX2(0.001f, interior_band_width / voxel_size);
openvdb::tools::sdfToFogVolume(*new_grid);
if (density != 1.0f) {
openvdb::tools::foreach (new_grid->beginValueOn(),
[&](const openvdb::FloatGrid::ValueOnIter &iter) {
iter.modifyValue([&](float &value) { value *= density; });
});
openvdb::FloatGrid::Ptr new_grid;
if (fill_volume) {
/* Setting the interior bandwidth to FLT_MAX, will make it fill the entire volume. */
new_grid = openvdb::tools::meshToVolume<openvdb::FloatGrid>(
mesh_adapter, {}, exterior, FLT_MAX);
}
else {
new_grid = openvdb::tools::meshToVolume<openvdb::FloatGrid>(
mesh_adapter, {}, exterior, interior);
}
/* Give each grid cell a fixed density for now. */
openvdb::tools::foreach (
new_grid->beginValueOn(),
[density](const openvdb::FloatGrid::ValueOnIter &iter) { iter.setValue(density); });
return new_grid;
}
@@ -185,12 +190,33 @@ VolumeGrid *fog_volume_grid_add_from_mesh(Volume *volume,
const Mesh *mesh,
const float4x4 &mesh_to_volume_space_transform,
const float voxel_size,
const bool fill_volume,
const float exterior_band_width,
const float interior_band_width,
const float density)
{
openvdb::FloatGrid::Ptr mesh_grid = mesh_to_fog_volume_grid(
mesh, mesh_to_volume_space_transform, voxel_size, interior_band_width, density);
return mesh_grid ? BKE_volume_grid_add_vdb(*volume, name, std::move(mesh_grid)) : nullptr;
VolumeGrid *c_grid = BKE_volume_grid_add(volume, name.c_str(), VOLUME_GRID_FLOAT);
openvdb::FloatGrid::Ptr grid = openvdb::gridPtrCast<openvdb::FloatGrid>(
BKE_volume_grid_openvdb_for_write(volume, c_grid, false));
/* Generate grid from mesh */
openvdb::FloatGrid::Ptr mesh_grid = mesh_to_fog_volume_grid(mesh,
mesh_to_volume_space_transform,
voxel_size,
fill_volume,
exterior_band_width,
interior_band_width,
density);
if (mesh_grid != nullptr) {
/* Merge the generated grid. Should be cheap because grid has just been created. */
grid->merge(*mesh_grid);
/* Change transform so that the index space is correctly transformed to object space. */
grid->transform().postScale(voxel_size);
}
/* Set class to "Fog Volume". */
grid->setGridClass(openvdb::GRID_FOG_VOLUME);
return c_grid;
}
VolumeGrid *sdf_volume_grid_add_from_mesh(Volume *volume,