Fix the logic so that when value is precisely zero it is still read in as long as its residual is not -1.

Author: aseth1

OpenSim/Common/C3DFileAdapter.cpp

@@ -120,11 +120,12 @@ C3DFileAdapter::extendRead(const std::string& fileName) const {
                 // BTK reads empty values as zero, but sets a "residual" value
                 // to -1 and it is how it knows to export these values as 
                 // blank, instead of 0,  when exporting to .trc
-                if (!pt->GetValues().row(f).isZero() &&    //not precisely zero
+                // Read in value if it is not zero or residual is not -1
+                if (!pt->GetValues().row(f).isZero() ||    //not precisely zero
                     (pt->GetResiduals().coeff(f) != -1) ) {//residual is not -1
                     row[m] = SimTK::Vec3{ pt->GetValues().coeff(f, 0),
-                                           pt->GetValues().coeff(f, 1),
-                                           pt->GetValues().coeff(f, 2) };
+                                          pt->GetValues().coeff(f, 1),
+                                          pt->GetValues().coeff(f, 2) };
                 }
                 ++m;
             }