diff -Nur meshlab.orig/src/external/structuresynth/ssynth/SyntopiaCore/GLEngine/Raytracer/VoxelStepper.cpp meshlab/src/external/structuresynth/ssynth/SyntopiaCore/GLEngine/Raytracer/VoxelStepper.cpp
--- meshlab.orig/src/external/structuresynth/ssynth/SyntopiaCore/GLEngine/Raytracer/VoxelStepper.cpp	2013-05-23 01:09:58.000000000 +1000
+++ meshlab/src/external/structuresynth/ssynth/SyntopiaCore/GLEngine/Raytracer/VoxelStepper.cpp	2016-05-23 12:55:48.495725226 +1000
@@ -122,7 +122,7 @@
 						currentT = p;
 
 						// We do not intersect grid.
-						if (!found) return false;
+						if (!found) return 0;
 				}
 
 				stepX = (dir.x() > 0) ? 1 : -1;
diff -Nur meshlab.orig/src/external/structuresynth-1.5/ssynth/SyntopiaCore/GLEngine/Raytracer/VoxelStepper.cpp meshlab/src/external/structuresynth-1.5/ssynth/SyntopiaCore/GLEngine/Raytracer/VoxelStepper.cpp
--- meshlab.orig/src/external/structuresynth-1.5/ssynth/SyntopiaCore/GLEngine/Raytracer/VoxelStepper.cpp	2014-02-07 20:38:23.000000000 +1100
+++ meshlab/src/external/structuresynth-1.5/ssynth/SyntopiaCore/GLEngine/Raytracer/VoxelStepper.cpp	2016-05-23 12:55:58.752439956 +1000
@@ -122,7 +122,7 @@
 						currentT = p;
 
 						// We do not intersect grid.
-						if (!found) return false;
+						if (!found) return 0;
 				}
 
 				stepX = (dir.x() > 0) ? 1 : -1;