Differential D8401 Diff 27595 intern/cycles/render/mesh_volume.cpp

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intern/cycles/render/mesh_volume.cpp

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* Unless required by applicable law or agreed to in writing, software		* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,		* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and		* See the License for the specific language governing permissions and
* limitations under the License.		* limitations under the License.
*/		*/

#include "render/attribute.h"		#include "render/attribute.h"
		#include "render/image_vdb.h"
#include "render/mesh.h"		#include "render/mesh.h"
#include "render/scene.h"		#include "render/scene.h"

		#ifdef WITH_OPENVDB
		# include <openvdb/tools/Dense.h>
		# include <openvdb/tools/GridTransformer.h>
		brechtUnsubmitted Not Done Inline Actions Cycles should continue to build without OpenVDB, even if it's without optimized bounding mesh. So there needs to be `#ifdef WITH_OPENVDB` in this file. brecht: Cycles should continue to build without OpenVDB, even if it's without optimized bounding mesh.
		# include <openvdb/tools/Morphology.h>
		#endif

#include "util/util_foreach.h"		#include "util/util_foreach.h"
#include "util/util_hash.h"		#include "util/util_hash.h"
#include "util/util_logging.h"		#include "util/util_logging.h"
		#include "util/util_openvdb.h"
#include "util/util_progress.h"		#include "util/util_progress.h"
#include "util/util_types.h"		#include "util/util_types.h"

CCL_NAMESPACE_BEGIN		CCL_NAMESPACE_BEGIN

const int64_t VOXEL_INDEX_NONE = -1;

static int64_t compute_voxel_index(const int3 &resolution, int64_t x, int64_t y, int64_t z)
{
if (x < 0 \|\| x >= resolution.x) {
return VOXEL_INDEX_NONE;
}
else if (y < 0 \|\| y >= resolution.y) {
return VOXEL_INDEX_NONE;
}
else if (z < 0 \|\| z >= resolution.z) {
return VOXEL_INDEX_NONE;
}

return x + y * resolution.x + z * resolution.x * resolution.y;
}

struct QuadData {		struct QuadData {
int v0, v1, v2, v3;		int v0, v1, v2, v3;

float3 normal;		float3 normal;
};		};

enum {		enum {
QUAD_X_MIN = 0,		QUAD_X_MIN = 0,
▲ Show 20 Lines • Show All 64 Lines • ▼ Show 20 Lines	static void create_quad(int3 corners[8],
quad.v1 = add_vertex(corners[quads_indices[face_index][1]], vertices, res, used_verts);		quad.v1 = add_vertex(corners[quads_indices[face_index][1]], vertices, res, used_verts);
quad.v2 = add_vertex(corners[quads_indices[face_index][2]], vertices, res, used_verts);		quad.v2 = add_vertex(corners[quads_indices[face_index][2]], vertices, res, used_verts);
quad.v3 = add_vertex(corners[quads_indices[face_index][3]], vertices, res, used_verts);		quad.v3 = add_vertex(corners[quads_indices[face_index][3]], vertices, res, used_verts);
quad.normal = quads_normals[face_index];		quad.normal = quads_normals[face_index];

quads.push_back(quad);		quads.push_back(quad);
}		}

struct VolumeParams {
int3 resolution;
float3 cell_size;
float3 start_point;
int pad_size;
};

static const int CUBE_SIZE = 8;

/* Create a mesh from a volume.		/* Create a mesh from a volume.
*		*
* The way the algorithm works is as follows:		* The way the algorithm works is as follows:
*		*
* - The coordinates of active voxels from a dense volume (or 3d image) are		* - The topologies of input OpenVDB grids are merged into a temporary grid.
* gathered inside an auxiliary volume.		* - Voxels of the temporary grid are dilated to account for the padding necessary for volume
* - Each set of coordinates of an CUBE_SIZE cube are mapped to the same		* sampling.
* coordinate of the auxiliary volume.		* - Quads are created on the boundary between active and inactive leaf nodes of the temporary
* - Quads are created between active and non-active voxels in the auxiliary		* grid.
* volume to generate a tight mesh around the volume.
*/		*/
class VolumeMeshBuilder {		class VolumeMeshBuilder {
/* Auxiliary volume that is used to check if a node already added. */
vector<char> grid;

/* The resolution of the auxiliary volume, set to be equal to 1/CUBE_SIZE
* of the original volume on each axis. */
int3 res;

size_t number_of_nodes;

/* Offset due to padding in the original grid. Padding will transform the
* coordinates of the original grid from 0...res to -padding...res+padding,
* so some coordinates are negative, and we need to properly account for
* them. */
int3 pad_offset;

VolumeParams *params;

public:		public:
VolumeMeshBuilder(VolumeParams *volume_params);		#ifdef WITH_OPENVDB
		/* use a MaskGrid to store the topology to save memory */
		openvdb::MaskGrid::Ptr topology_grid;
		openvdb::CoordBBox bbox;
		#endif
		bool first_grid;

		VolumeMeshBuilder();

		#ifdef WITH_OPENVDB
		void add_grid(openvdb::GridBase::ConstPtr grid, bool do_clipping, float volume_clipping);
		#endif

void add_node(int x, int y, int z);		void add_padding(int pad_size);

void add_node_with_padding(int x, int y, int z);		void create_mesh(vector<float3> &vertices,
		vector<int> &indices,
void create_mesh(vector<float3> &vertices, vector<int> &indices, vector<float3> &face_normals);		vector<float3> &face_normals,
		const float face_overlap_avoidance);

private:
void generate_vertices_and_quads(vector<int3> &vertices_is, vector<QuadData> &quads);		void generate_vertices_and_quads(vector<int3> &vertices_is, vector<QuadData> &quads);

void convert_object_space(const vector<int3> &vertices, vector<float3> &out_vertices);		void convert_object_space(const vector<int3> &vertices,
		vector<float3> &out_vertices,
		const float face_overlap_avoidance);

void convert_quads_to_tris(const vector<QuadData> &quads,		void convert_quads_to_tris(const vector<QuadData> &quads,
vector<int> &tris,		vector<int> &tris,
vector<float3> &face_normals);		vector<float3> &face_normals);
};

VolumeMeshBuilder::VolumeMeshBuilder(VolumeParams *volume_params)		bool empty_grid() const;

		#ifdef WITH_OPENVDB
		template <typename GridType>
		void merge_grid(openvdb::GridBase::ConstPtr grid, bool do_clipping, float volume_clipping)
{		{
params = volume_params;		typename GridType::ConstPtr typed_grid = openvdb::gridConstPtrCast<GridType>(grid);
number_of_nodes = 0;

const int64_t x = divide_up(params->resolution.x, CUBE_SIZE);		if (do_clipping) {
const int64_t y = divide_up(params->resolution.y, CUBE_SIZE);		using ValueType = typename GridType::ValueType;
const int64_t z = divide_up(params->resolution.z, CUBE_SIZE);		typename GridType::Ptr copy = typed_grid->deepCopy();
		typename GridType::ValueOnIter iter = copy->beginValueOn();

/* Adding 2*pad_size since we pad in both positive and negative directions		for (; iter; ++iter) {
* along the axis. */		if (iter.getValue() < ValueType(volume_clipping)) {
const int64_t px = divide_up(params->resolution.x + 2 * params->pad_size, CUBE_SIZE);		iter.setValueOff();
const int64_t py = divide_up(params->resolution.y + 2 * params->pad_size, CUBE_SIZE);		}
const int64_t pz = divide_up(params->resolution.z + 2 * params->pad_size, CUBE_SIZE);		}

res = make_int3(px, py, pz);		typed_grid = copy;
pad_offset = make_int3(px - x, py - y, pz - z);		}

grid.resize(px * py * pz, 0);		topology_grid->topologyUnion(*typed_grid);
}		}
		#endif
		};

void VolumeMeshBuilder::add_node(int x, int y, int z)		VolumeMeshBuilder::VolumeMeshBuilder()
{		{
/* Map coordinates to index space. */		first_grid = true;
const int index_x = (x / CUBE_SIZE) + pad_offset.x;
const int index_y = (y / CUBE_SIZE) + pad_offset.y;
const int index_z = (z / CUBE_SIZE) + pad_offset.z;

assert((index_x >= 0) && (index_y >= 0) && (index_z >= 0));

const int64_t index = compute_voxel_index(res, index_x, index_y, index_z);
if (index == VOXEL_INDEX_NONE) {
return;
}		}

/* We already have a node here. */		#ifdef WITH_OPENVDB
if (grid[index] == 1) {		void VolumeMeshBuilder::add_grid(openvdb::GridBase::ConstPtr grid, bool do_clipping, float volume_clipping)
return;		{
		/* set the transform of our grid from the first one */
		if (first_grid) {
		topology_grid = openvdb::MaskGrid::create();
		topology_grid->setTransform(grid->transform().copy());
		first_grid = false;
}		}
		/* if the transforms do not match, we need to resample one of the grids so that
++number_of_nodes;		* its index space registers with that of the other, here we resample our mask
		* grid so memory usage is kept low */
grid[index] = 1;		else if (topology_grid->transform() != grid->transform()) {
		openvdb::MaskGrid::Ptr temp_grid = topology_grid->copyWithNewTree();
		temp_grid->setTransform(grid->transform().copy());
		openvdb::tools::resampleToMatch<openvdb::tools::BoxSampler>(topology_grid, temp_grid);
		topology_grid = temp_grid;
		topology_grid->setTransform(grid->transform().copy());
}		}

void VolumeMeshBuilder::add_node_with_padding(int x, int y, int z)		if (grid->isType<openvdb::FloatGrid>()) {
{		merge_grid<openvdb::FloatGrid>(grid, do_clipping, volume_clipping);
for (int px = x - params->pad_size; px < x + params->pad_size; ++px) {		}
for (int py = y - params->pad_size; py < y + params->pad_size; ++py) {		else if (grid->isType<openvdb::Vec3fGrid>()) {
for (int pz = z - params->pad_size; pz < z + params->pad_size; ++pz) {		merge_grid<openvdb::Vec3fGrid>(grid, do_clipping, volume_clipping);
add_node(px, py, pz);		}
		else if (grid->isType<openvdb::Vec4fGrid>()) {
		merge_grid<openvdb::Vec4fGrid>(grid, do_clipping, volume_clipping);
		}
		else if (grid->isType<openvdb::BoolGrid>()) {
		merge_grid<openvdb::BoolGrid>(grid, do_clipping, volume_clipping);
		}
		else if (grid->isType<openvdb::DoubleGrid>()) {
		merge_grid<openvdb::DoubleGrid>(grid, do_clipping, volume_clipping);
}		}
		else if (grid->isType<openvdb::Int32Grid>()) {
		merge_grid<openvdb::Int32Grid>(grid, do_clipping, volume_clipping);
}		}
		else if (grid->isType<openvdb::Int64Grid>()) {
		merge_grid<openvdb::Int64Grid>(grid, do_clipping, volume_clipping);
}		}
		else if (grid->isType<openvdb::Vec3IGrid>()) {
		merge_grid<openvdb::Vec3IGrid>(grid, do_clipping, volume_clipping);
		}
		else if (grid->isType<openvdb::Vec3dGrid>()) {
		merge_grid<openvdb::Vec3dGrid>(grid, do_clipping, volume_clipping);
		}
		else if (grid->isType<openvdb::MaskGrid>()) {
		topology_grid->topologyUnion(*openvdb::gridConstPtrCast<openvdb::MaskGrid>(grid));
		}
		}
		#endif

		void VolumeMeshBuilder::add_padding(int pad_size)
		{
		#ifdef WITH_OPENVDB
		openvdb::tools::dilateVoxels(topology_grid->tree(), pad_size);
		#else
		(void)pad_size;
		#endif
}		}

void VolumeMeshBuilder::create_mesh(vector<float3> &vertices,		void VolumeMeshBuilder::create_mesh(vector<float3> &vertices,
vector<int> &indices,		vector<int> &indices,
vector<float3> &face_normals)		vector<float3> &face_normals,
		const float face_overlap_avoidance)
{		{
/* We create vertices in index space (is), and only convert them to object		/* We create vertices in index space (is), and only convert them to object
* space when done. */		* space when done. */
vector<int3> vertices_is;		vector<int3> vertices_is;
vector<QuadData> quads;		vector<QuadData> quads;

generate_vertices_and_quads(vertices_is, quads);		generate_vertices_and_quads(vertices_is, quads);

convert_object_space(vertices_is, vertices);		convert_object_space(vertices_is, vertices, face_overlap_avoidance);

convert_quads_to_tris(quads, indices, face_normals);		convert_quads_to_tris(quads, indices, face_normals);
}		}

void VolumeMeshBuilder::generate_vertices_and_quads(vector<ccl::int3> &vertices_is,		void VolumeMeshBuilder::generate_vertices_and_quads(vector<ccl::int3> &vertices_is,
vector<QuadData> &quads)		vector<QuadData> &quads)
{		{
unordered_map<size_t, int> used_verts;		#ifdef WITH_OPENVDB
		const openvdb::MaskGrid::TreeType &tree = topology_grid->tree();
		tree.evalLeafBoundingBox(bbox);

for (int z = 0; z < res.z; ++z) {		const int3 resolution = make_int3(bbox.dim().x(), bbox.dim().y(), bbox.dim().z());
for (int y = 0; y < res.y; ++y) {
for (int x = 0; x < res.x; ++x) {		unordered_map<size_t, int> used_verts;
int64_t voxel_index = compute_voxel_index(res, x, y, z);
if (grid[voxel_index] == 0) {
continue;
}

/* Compute min and max coords of the node in index space. */		for (auto iter = tree.cbeginLeaf(); iter; ++iter) {
int3 min = make_int3((x - pad_offset.x) * CUBE_SIZE,		openvdb::CoordBBox leaf_bbox = iter->getNodeBoundingBox();
(y - pad_offset.y) * CUBE_SIZE,		/* +1 to convert from exclusive to include bounds. */
(z - pad_offset.z) * CUBE_SIZE);		leaf_bbox.max() = leaf_bbox.max().offsetBy(1);

/* Maximum is just CUBE_SIZE voxels away from minimum on each axis. */		int3 min = make_int3(leaf_bbox.min().x(), leaf_bbox.min().y(), leaf_bbox.min().z());
int3 max = make_int3(min.x + CUBE_SIZE, min.y + CUBE_SIZE, min.z + CUBE_SIZE);		int3 max = make_int3(leaf_bbox.max().x(), leaf_bbox.max().y(), leaf_bbox.max().z());

int3 corners[8] = {		int3 corners[8] = {
make_int3(min[0], min[1], min[2]),		make_int3(min[0], min[1], min[2]),
make_int3(max[0], min[1], min[2]),		make_int3(max[0], min[1], min[2]),
make_int3(max[0], max[1], min[2]),		make_int3(max[0], max[1], min[2]),
make_int3(min[0], max[1], min[2]),		make_int3(min[0], max[1], min[2]),
make_int3(min[0], min[1], max[2]),		make_int3(min[0], min[1], max[2]),
make_int3(max[0], min[1], max[2]),		make_int3(max[0], min[1], max[2]),
make_int3(max[0], max[1], max[2]),		make_int3(max[0], max[1], max[2]),
make_int3(min[0], max[1], max[2]),		make_int3(min[0], max[1], max[2]),
};		};

/* Only create a quad if on the border between an active and		/* Only create a quad if on the border between an active and an inactive leaf.
* an inactive node.		*
		* We verify that a leaf exists by probing a coordinate that is at its center,
		* to do so we compute the center of the current leaf and offset this coordinate
		* by the size of a leaf in each direction.
*/		*/
		static const int LEAF_DIM = openvdb::MaskGrid::TreeType::LeafNodeType::DIM;
		auto center = leaf_bbox.min() + openvdb::Coord(LEAF_DIM / 2);

voxel_index = compute_voxel_index(res, x - 1, y, z);		if (!tree.probeLeaf(openvdb::Coord(center.x() - LEAF_DIM, center.y(), center.z()))) {
if (voxel_index == VOXEL_INDEX_NONE \|\| grid[voxel_index] == 0) {		create_quad(corners, vertices_is, quads, resolution, used_verts, QUAD_X_MIN);
create_quad(corners, vertices_is, quads, res, used_verts, QUAD_X_MIN);
}		}

voxel_index = compute_voxel_index(res, x + 1, y, z);		if (!tree.probeLeaf(openvdb::Coord(center.x() + LEAF_DIM, center.y(), center.z()))) {
if (voxel_index == VOXEL_INDEX_NONE \|\| grid[voxel_index] == 0) {		create_quad(corners, vertices_is, quads, resolution, used_verts, QUAD_X_MAX);
create_quad(corners, vertices_is, quads, res, used_verts, QUAD_X_MAX);
}		}

voxel_index = compute_voxel_index(res, x, y - 1, z);		if (!tree.probeLeaf(openvdb::Coord(center.x(), center.y() - LEAF_DIM, center.z()))) {
if (voxel_index == VOXEL_INDEX_NONE \|\| grid[voxel_index] == 0) {		create_quad(corners, vertices_is, quads, resolution, used_verts, QUAD_Y_MIN);
create_quad(corners, vertices_is, quads, res, used_verts, QUAD_Y_MIN);
}		}

voxel_index = compute_voxel_index(res, x, y + 1, z);		if (!tree.probeLeaf(openvdb::Coord(center.x(), center.y() + LEAF_DIM, center.z()))) {
if (voxel_index == VOXEL_INDEX_NONE \|\| grid[voxel_index] == 0) {		create_quad(corners, vertices_is, quads, resolution, used_verts, QUAD_Y_MAX);
create_quad(corners, vertices_is, quads, res, used_verts, QUAD_Y_MAX);
}		}

voxel_index = compute_voxel_index(res, x, y, z - 1);		if (!tree.probeLeaf(openvdb::Coord(center.x(), center.y(), center.z() - LEAF_DIM))) {
if (voxel_index == VOXEL_INDEX_NONE \|\| grid[voxel_index] == 0) {		create_quad(corners, vertices_is, quads, resolution, used_verts, QUAD_Z_MIN);
create_quad(corners, vertices_is, quads, res, used_verts, QUAD_Z_MIN);
}		}

voxel_index = compute_voxel_index(res, x, y, z + 1);		if (!tree.probeLeaf(openvdb::Coord(center.x(), center.y(), center.z() + LEAF_DIM))) {
if (voxel_index == VOXEL_INDEX_NONE \|\| grid[voxel_index] == 0) {		create_quad(corners, vertices_is, quads, resolution, used_verts, QUAD_Z_MAX);
create_quad(corners, vertices_is, quads, res, used_verts, QUAD_Z_MAX);
}
}
}		}
}		}
		#else
		(void)vertices_is;
		(void)quads;
		#endif
}		}

void VolumeMeshBuilder::convert_object_space(const vector<int3> &vertices,		void VolumeMeshBuilder::convert_object_space(const vector<int3> &vertices,
vector<float3> &out_vertices)		vector<float3> &out_vertices,
		const float face_overlap_avoidance)
{		{
		#ifdef WITH_OPENVDB
		/* compute the offset for the face overlap avoidance */
		bbox = topology_grid->evalActiveVoxelBoundingBox();
		openvdb::Coord dim = bbox.dim();

		float3 cell_size = make_float3(1.0f / dim.x(), 1.0f / dim.y(), 1.0f / dim.z());
		float3 point_offset = cell_size * face_overlap_avoidance;

out_vertices.reserve(vertices.size());		out_vertices.reserve(vertices.size());

for (size_t i = 0; i < vertices.size(); ++i) {		for (size_t i = 0; i < vertices.size(); ++i) {
float3 vertex = make_float3(vertices[i].x, vertices[i].y, vertices[i].z);		openvdb::math::Vec3d p = topology_grid->indexToWorld(
vertex *= params->cell_size;		openvdb::math::Vec3d(vertices[i].x, vertices[i].y, vertices[i].z));
vertex += params->start_point;		float3 vertex = make_float3((float)p.x(), (float)p.y(), (float)p.z());
		out_vertices.push_back(vertex + point_offset);
out_vertices.push_back(vertex);		}
}		#else
		(void)vertices;
		(void)out_vertices;
		(void)face_overlap_avoidance;
		#endif
}		}

void VolumeMeshBuilder::convert_quads_to_tris(const vector<QuadData> &quads,		void VolumeMeshBuilder::convert_quads_to_tris(const vector<QuadData> &quads,
vector<int> &tris,		vector<int> &tris,
vector<float3> &face_normals)		vector<float3> &face_normals)
{		{
int index_offset = 0;		int index_offset = 0;
tris.resize(quads.size() * 6);		tris.resize(quads.size() * 6);
Show All 9 Lines	for (size_t i = 0; i < quads.size(); ++i) {
tris[index_offset++] = quads[i].v0;		tris[index_offset++] = quads[i].v0;
tris[index_offset++] = quads[i].v3;		tris[index_offset++] = quads[i].v3;
tris[index_offset++] = quads[i].v2;		tris[index_offset++] = quads[i].v2;

face_normals.push_back(quads[i].normal);		face_normals.push_back(quads[i].normal);
}		}
}		}

/* ************************************************************************** */		bool VolumeMeshBuilder::empty_grid() const
		{
		#ifdef WITH_OPENVDB
		return !topology_grid \|\| topology_grid->tree().leafCount() == 0;
		#else
		return true;
		#endif
		}

struct VoxelAttributeGrid {		#ifdef WITH_OPENVDB
float *data;		template<typename GridType>
int channels;		static openvdb::GridBase::ConstPtr openvdb_grid_from_device_texture(device_texture *image_memory,
};		float volume_clipping,
		Transform transform_3d)
		{
		using ValueType = typename GridType::ValueType;

		openvdb::CoordBBox dense_bbox(0,
		0,
		0,
		image_memory->data_width - 1,
		image_memory->data_height - 1,
		image_memory->data_depth - 1);
		openvdb::tools::Dense<ValueType, openvdb::tools::MemoryLayout::LayoutXYZ> dense(
		dense_bbox, static_cast<ValueType *>(image_memory->host_pointer));

		typename GridType::Ptr sparse = GridType::create(ValueType(0.0f));
		openvdb::tools::copyFromDense(dense, *sparse, ValueType(volume_clipping));

		/* copyFromDense will remove any leaf node that contains constant data and replace it with a tile,
		* however, we need to preserve the leaves in order to generate the mesh, so revoxelize the leaves
		* that were pruned. This should not affect areas that were skipped due to the volume_clipping parameter. */
		sparse->tree().voxelizeActiveTiles();

		/* Compute index to world matrix. */
		float3 voxel_size = make_float3(1.0f / image_memory->data_width, 1.0f / image_memory->data_height, 1.0f / image_memory->data_depth);

		transform_3d = transform_inverse(transform_3d);

		openvdb::Mat4R index_to_world_mat((double)(voxel_size.x * transform_3d[0][0]), 0.0, 0.0, 0.0,
		0.0, (double)(voxel_size.y * transform_3d[1][1]), 0.0, 0.0,
		0.0, 0.0, (double)(voxel_size.z * transform_3d[2][2]), 0.0,
		(double)transform_3d[0][3], (double)transform_3d[1][3], (double)transform_3d[2][3], 1.0);

		openvdb::math::Transform::Ptr index_to_world_tfm = openvdb::math::Transform::createLinearTransform(index_to_world_mat);

		sparse->setTransform(index_to_world_tfm);

		return sparse;
		}
		#endif

		/* ************************************************************************** */

void GeometryManager::create_volume_mesh(Mesh *mesh, Progress &progress)		void GeometryManager::create_volume_mesh(Mesh *mesh, Progress &progress)
{		{
string msg = string_printf("Computing Volume Mesh %s", mesh->name.c_str());		string msg = string_printf("Computing Volume Mesh %s", mesh->name.c_str());
progress.set_status("Updating Mesh", msg);		progress.set_status("Updating Mesh", msg);

vector<VoxelAttributeGrid> voxel_grids;		VolumeMeshBuilder builder;

/* Compute volume parameters. */
VolumeParams volume_params;
volume_params.resolution = make_int3(0, 0, 0);

Transform transform = transform_identity();

		#ifdef WITH_OPENVDB
foreach (Attribute &attr, mesh->attributes.attributes) {		foreach (Attribute &attr, mesh->attributes.attributes) {
if (attr.element != ATTR_ELEMENT_VOXEL) {		if (attr.element != ATTR_ELEMENT_VOXEL) {
continue;		continue;
}		}

		bool do_clipping = false;

ImageHandle &handle = attr.data_voxel();		ImageHandle &handle = attr.data_voxel();

		/* Try building from OpenVDB grid directly. */
		VDBImageLoader *vdb_loader = handle.vdb_loader();
		openvdb::GridBase::ConstPtr grid;
		if (vdb_loader) {
		grid = vdb_loader->get_grid();

		/* If building from an OpenVDB grid, we need to manually clip the values. */
		do_clipping = true;
		}

		/* Else fall back to creating an OpenVDB grid from the dense volume data. */
		if (!grid) {
device_texture *image_memory = handle.image_memory();		device_texture *image_memory = handle.image_memory();
int3 resolution = make_int3(
image_memory->data_width, image_memory->data_height, image_memory->data_depth);

if (volume_params.resolution == make_int3(0, 0, 0)) {		if (image_memory->data_elements == 1) {
volume_params.resolution = resolution;		grid = openvdb_grid_from_device_texture<openvdb::FloatGrid>(image_memory,
		mesh->volume_clipping,
		handle.metadata().transform_3d);
		}
		else if (image_memory->data_elements == 3) {
		grid = openvdb_grid_from_device_texture<openvdb::Vec3fGrid>(image_memory,
		mesh->volume_clipping,
		handle.metadata().transform_3d);
		}
		else if (image_memory->data_elements == 4) {
		grid = openvdb_grid_from_device_texture<openvdb::Vec4fGrid>(image_memory,
		mesh->volume_clipping,
		handle.metadata().transform_3d);
}		}
else if (volume_params.resolution != resolution) {
/* TODO: support this as it's common for OpenVDB. */
VLOG(1) << "Can't create accurate volume mesh, all voxel grid resolutions must be equal\n";
continue;
}		}

VoxelAttributeGrid voxel_grid;		if (grid) {
voxel_grid.data = static_cast<float *>(image_memory->host_pointer);		builder.add_grid(grid, do_clipping, mesh->volume_clipping);
voxel_grid.channels = image_memory->data_elements;
voxel_grids.push_back(voxel_grid);

/* TODO: support multiple transforms. */
if (image_memory->info.use_transform_3d) {
transform = image_memory->info.transform_3d;
}		}
}		}
		#endif

if (voxel_grids.empty()) {		if (builder.empty_grid()) {
return;		return;
}		}

/* Compute padding. */		/* Compute padding. */
Shader *volume_shader = NULL;		Shader *volume_shader = NULL;
int pad_size = 0;		int pad_size = 0;

foreach (Shader *shader, mesh->used_shaders) {		foreach (Shader *shader, mesh->used_shaders) {
Show All 12 Lines	foreach (Shader *shader, mesh->used_shaders) {

break;		break;
}		}

if (!volume_shader) {		if (!volume_shader) {
return;		return;
}		}

/* Compute start point and cell size from transform. */		builder.add_padding(pad_size);
const int3 resolution = volume_params.resolution;
float3 start_point = make_float3(0.0f, 0.0f, 0.0f);
float3 cell_size = make_float3(1.0f / resolution.x, 1.0f / resolution.y, 1.0f / resolution.z);

/* TODO: support arbitrary transforms, not just scale + translate. */
const Transform itfm = transform_inverse(transform);
start_point = transform_point(&itfm, start_point);
cell_size = transform_direction(&itfm, cell_size);

/* Slightly offset vertex coordinates to avoid overlapping faces with other		/* Slightly offset vertex coordinates to avoid overlapping faces with other
* volumes or meshes. The proper solution would be to improve intersection in		* volumes or meshes. The proper solution would be to improve intersection in
* the kernel to support robust handling of multiple overlapping faces or use		* the kernel to support robust handling of multiple overlapping faces or use
* an all-hit intersection similar to shadows. */		* an all-hit intersection similar to shadows. */
const float3 face_overlap_avoidance = cell_size * 0.1f *		const float face_overlap_avoidance = 0.1f * hash_uint_to_float(hash_string(mesh->name.c_str()));
hash_uint_to_float(hash_string(mesh->name.c_str()));

volume_params.start_point = start_point + face_overlap_avoidance;
volume_params.cell_size = cell_size;
volume_params.pad_size = pad_size;

/* Build bounding mesh around non-empty volume cells. */
VolumeMeshBuilder builder(&volume_params);
const float clipping = mesh->volume_clipping;

for (int z = 0; z < resolution.z; ++z) {
for (int y = 0; y < resolution.y; ++y) {
for (int x = 0; x < resolution.x; ++x) {
int64_t voxel_index = compute_voxel_index(resolution, x, y, z);

for (size_t i = 0; i < voxel_grids.size(); ++i) {
const VoxelAttributeGrid &voxel_grid = voxel_grids[i];
const int channels = voxel_grid.channels;

for (int c = 0; c < channels; c++) {
if (voxel_grid.data[voxel_index * channels + c] >= clipping) {
builder.add_node_with_padding(x, y, z);
break;
}
}
}
}
}
}

/* Create mesh. */		/* Create mesh. */
vector<float3> vertices;		vector<float3> vertices;
vector<int> indices;		vector<int> indices;
vector<float3> face_normals;		vector<float3> face_normals;
builder.create_mesh(vertices, indices, face_normals);		builder.create_mesh(vertices, indices, face_normals, face_overlap_avoidance);

mesh->clear(true);		mesh->clear(true);
mesh->reserve_mesh(vertices.size(), indices.size() / 3);		mesh->reserve_mesh(vertices.size(), indices.size() / 3);
mesh->used_shaders.push_back(volume_shader);		mesh->used_shaders.push_back(volume_shader);

for (size_t i = 0; i < vertices.size(); ++i) {		for (size_t i = 0; i < vertices.size(); ++i) {
mesh->add_vertex(vertices[i]);		mesh->add_vertex(vertices[i]);
}		}
Show All 10 Lines	#endif
}		}

/* Print stats. */		/* Print stats. */
VLOG(1) << "Memory usage volume mesh: "		VLOG(1) << "Memory usage volume mesh: "
<< ((vertices.size() + face_normals.size()) * sizeof(float3) +		<< ((vertices.size() + face_normals.size()) * sizeof(float3) +
indices.size() * sizeof(int)) /		indices.size() * sizeof(int)) /
(1024.0 * 1024.0)		(1024.0 * 1024.0)
<< "Mb.";		<< "Mb.";

VLOG(1) << "Memory usage volume grid: "
<< (resolution.x * resolution.y * resolution.z * sizeof(float)) / (1024.0 * 1024.0)
<< "Mb.";
}		}

CCL_NAMESPACE_END		CCL_NAMESPACE_END