Fix bug with nanovdb indexing in cmd/nanovdb2pbrt.cpp

(Removed the downsampling functinoality for simplicity along the way.)

Fixes #452.

src/pbrt/cmd/nanovdb2pbrt.cpp

@@ -51,8 +51,6 @@ static void usage(const std::string &msg = {}) {
             R"(usage: nanovdb2pbrt [<options>] <filename.nvdb>
 
 Options:
-  --downsample <n>     Number of times to 2x downsample the volume.
-                       Default: 0
   --grid <name>        Name of grid to extract. Default: "density"
 )");
     exit(msg.empty() ? 0 : 1);
@@ -100,63 +98,19 @@ int main(int argc, char *argv[]) {
     Bounds3f bounds(Point3f(bbox.min()[0], bbox.min()[1], bbox.min()[2]),
                     Point3f(bbox.max()[0], bbox.max()[1], bbox.max()[2]));
 
-    int nx = floatGrid->indexBBox().dim()[0];
-    int ny = floatGrid->indexBBox().dim()[1];
-    int nz = floatGrid->indexBBox().dim()[2];
-
     std::vector<Float> values;
 
-    int z0 = 0, z1 = nz;
-    int y0 = 0, y1 = ny;
-    int x0 = 0, x1 = nx;
-
-    // Fix the resolution to be a multiple of 2^downsample just to make
-    // downsampling easy. Chop off one at a time from the bottom and top
-    // of the range until we get there; the bounding box is updated as
-    // well so that the remaining volume doesn't shift spatially.
-    auto round = [=](int &low, int &high, Float &c0, Float &c1) {
-        Float delta = (c1-c0) / (high-low);
-        int mult = 1 << downsample; // want a multiple of this in resolution
-        while ((high - low) % mult) {
-            ++low;
-            c0 += delta;
-            if ((high - low) % mult) {
-                --high;
-                c1 -= delta;
-            }
-        }
-        return high - low;
-    };
-    nz = round(z0, z1, bounds.pMin.z, bounds.pMax.z);
-    ny = round(y0, y1, bounds.pMin.y, bounds.pMax.y);
-    nx = round(x0, x1, bounds.pMin.x, bounds.pMax.x);
+    int x0 = floatGrid->indexBBox().min()[0], x1 = floatGrid->indexBBox().max()[0]+1;
+    int y0 = floatGrid->indexBBox().min()[1], y1 = floatGrid->indexBBox().max()[1]+1;
+    int z0 = floatGrid->indexBBox().min()[2], z1 = floatGrid->indexBBox().max()[2]+1;
 
-    for (int z = z0; z < z1; ++z)
-        for (int y = y0; y < y1; ++y)
-            for (int x = x0; x < x1; ++x) {
+    for (int z = z0; z <= z1; ++z)
+        for (int y = y0; y <= y1; ++y)
+            for (int x = x0; x <= x1; ++x) {
                 values.push_back(floatGrid->tree().getValue({x, y, z}));
             }
 
-    while (downsample > 0) {
-        std::vector<Float> v2;
-        for (int z = 0; z < nz/2; ++z)
-            for (int y = 0; y < ny/2; ++y)
-                for (int x = 0; x < nx/2; ++x) {
-                    auto v = [&](int dx, int dy, int dz) -> Float{
-                        return values[(2*x+dx) + nx * ((2*y+dy) + ny * (2*z+dz))];
-                    };
-                    v2.push_back((v(0,0,0) + v(1,0,0) + v(0,1,0) + v(1,1,0) +
-                                  v(0,0,1) + v(1,0,1) + v(0,1,1) + v(1,1,1))/8);
-                }
-
-        values = std::move(v2);
-        nx /= 2;
-        ny /= 2;
-        nz /= 2;
-        --downsample;
-    }
-
-    printf("\"integer nx\" %d \"integer ny\" %d  \"integer nz\" %d\n", nx, ny, nz);
+    printf("\"integer nx\" %d \"integer ny\" %d  \"integer nz\" %d\n", 1+x1-x0, 1+y1-y0, 1+z1-z0);
     printf("\t\"point3 p0\" [ %f %f %f ] \"point3 p1\" [ %f %f %f ]\n",
            bounds.pMin.x, bounds.pMin.y, bounds.pMin.z,
            bounds.pMax.x, bounds.pMax.y, bounds.pMax.z);