2.5x speedup of hollowing.

Triangle removal is slightly broken

src/libslic3r/OpenVDBUtils.cpp

@@ -14,6 +14,7 @@
 #include <openvdb/tools/VolumeToMesh.h>
 #include <openvdb/tools/Composite.h>
 #include <openvdb/tools/LevelSetRebuild.h>
+#include <openvdb/tools/FastSweeping.h>
 
 //#include "MTUtils.hpp"
 
@@ -69,16 +70,26 @@ openvdb::FloatGrid::Ptr mesh_to_grid(const indexed_triangle_set &    mesh,
         else if (subgrid) grid = std::move(subgrid);
     }
 
-    if (grid) {
-        grid = openvdb::tools::levelSetRebuild(*grid, 0., exteriorBandWidth,
-                                               interiorBandWidth);
+    if (grid && meshparts.size() >= 1) {
+//        grid = openvdb::tools::levelSetRebuild(*grid, 0.);
     } else if(meshparts.empty()) {
         // Splitting failed, fall back to hollow the original mesh
         grid = openvdb::tools::meshToVolume<openvdb::FloatGrid>(
-            TriangleMeshDataAdapter{mesh}, tr, exteriorBandWidth,
-            interiorBandWidth);
+            TriangleMeshDataAdapter{mesh}, tr);
     }
 
+    constexpr int DilateIterations = 1;
+
+    grid = openvdb::tools::dilateSdf(
+        *grid, interiorBandWidth, openvdb::tools::NN_FACE_EDGE,
+        DilateIterations,
+        openvdb::tools::FastSweepingDomain::SWEEP_LESS_THAN_ISOVALUE);
+
+    grid = openvdb::tools::dilateSdf(
+        *grid, exteriorBandWidth, openvdb::tools::NN_FACE_EDGE,
+        DilateIterations,
+        openvdb::tools::FastSweepingDomain::SWEEP_GREATER_THAN_ISOVALUE);
+
     grid->insertMeta("voxel_scale", openvdb::FloatMetadata(voxel_scale));
 
     return grid;
@@ -131,4 +142,15 @@ openvdb::FloatGrid::Ptr redistance_grid(const openvdb::FloatGrid &grid,
     return new_grid;
 }
 
+openvdb::FloatGrid::Ptr redistance_grid(const openvdb::FloatGrid &grid,
+                                        double                    iso)
+{
+    auto new_grid = openvdb::tools::levelSetRebuild(grid, float(iso));
+
+       // Copies voxel_scale metadata, if it exists.
+    new_grid->insertMeta(*grid.deepCopyMeta());
+
+    return new_grid;
+}
+
 } // namespace Slic3r

src/libslic3r/OpenVDBUtils.hpp

@@ -37,10 +37,13 @@ indexed_triangle_set grid_to_mesh(const openvdb::FloatGrid &grid,
                                   double                    adaptivity = 0.0,
                                   bool relaxDisorientedTriangles = true);
 
+openvdb::FloatGrid::Ptr redistance_grid(const openvdb::FloatGrid &grid,
+                                        double                    iso);
+
 openvdb::FloatGrid::Ptr redistance_grid(const openvdb::FloatGrid &grid,
                                         double                    iso,
-                                        double ext_range = 3.,
-                                        double int_range = 3.);
+                                        double ext_range,
+                                        double int_range);
 
 } // namespace Slic3r
 

src/libslic3r/SLA/Hollowing.cpp

@@ -12,6 +12,8 @@
 
 #include <boost/log/trivial.hpp>
 
+#include <openvdb/tools/FastSweeping.h>
+
 #include <libslic3r/MTUtils.hpp>
 #include <libslic3r/I18N.hpp>
 
@@ -65,13 +67,12 @@ static InteriorPtr generate_interior_verbose(const TriangleMesh & mesh,
 {
     double offset = voxel_scale * min_thickness;
     double D = voxel_scale * closing_dist;
-    float  out_range = 0.1f * float(offset);
-    float  in_range = 1.1f * float(offset + D);
+    float  in_range = /*1.1f * */float(offset + D);
 
     if (ctl.stopcondition()) return {};
     else ctl.statuscb(0, L("Hollowing"));
 
-    auto gridptr = mesh_to_grid(mesh.its, {}, voxel_scale, out_range, in_range);
+    auto gridptr = mesh_to_grid(mesh.its, {}, voxel_scale, 3., in_range);
 
     assert(gridptr);
 
@@ -84,9 +85,16 @@ static InteriorPtr generate_interior_verbose(const TriangleMesh & mesh,
     else ctl.statuscb(30, L("Hollowing"));
 
     double iso_surface = D;
-    auto   narrowb = double(in_range);
+    auto   narrowb = 3.; //double(in_range);
     gridptr = redistance_grid(*gridptr, -(offset + D), narrowb, narrowb);
 
+    constexpr int DilateIterations = 1;
+
+    gridptr = openvdb::tools::dilateSdf(
+        *gridptr, std::ceil(iso_surface),
+        openvdb::tools::NN_FACE_EDGE_VERTEX, DilateIterations,
+        openvdb::tools::FastSweepingDomain::SWEEP_GREATER_THAN_ISOVALUE);
+
     if (ctl.stopcondition()) return {};
     else ctl.statuscb(70, L("Hollowing"));
 
@@ -103,7 +111,7 @@ static InteriorPtr generate_interior_verbose(const TriangleMesh & mesh,
     interior->thickness = offset;
     interior->voxel_scale = voxel_scale;
     interior->nb_in = narrowb;
-    interior->nb_out = narrowb;
+    interior->nb_out = iso_surface;
 
     return interior;
 }

src/libslic3r/SLAPrintSteps.cpp

@@ -21,6 +21,8 @@
 
 #include "I18N.hpp"
 
+#include <libnest2d/tools/benchmark.h>
+
 //! macro used to mark string used at localization,
 //! return same string
 #define L(s) Slic3r::I18N::translate(s)
@@ -1116,7 +1118,14 @@ double SLAPrint::Steps::progressrange(SLAPrintStep step) const
 void SLAPrint::Steps::execute(SLAPrintObjectStep step, SLAPrintObject &obj)
 {
     switch(step) {
-    case slaposHollowing: hollow_model(obj); break;
+    case slaposHollowing: {
+        Benchmark bench;
+        bench.start();
+        hollow_model(obj);
+        bench.stop();
+        std::cout << "Hollowing took " << bench.getElapsedSec() << " seconds" << std::endl;
+        break;
+    }
     case slaposDrillHoles: drill_holes(obj); break;
     case slaposObjectSlice: slice_model(obj); break;
     case slaposSupportPoints:  support_points(obj); break;