VTK: Read geometry only on first timestep, log displacements per timestep

Move points and connectivity reading inside the isFirst guard to avoid redundant parsing on subsequent timesteps. Move displacements reading outside the guard so they are read for every timestep, and update the log message accordingly.

ApplicationLibCode/FileInterface/RifVtkImportUtil.cpp

@@ -20,9 +20,11 @@
 
 #include "RiaStdStringTools.h"
 
+#include "fast_float/fast_float.h"
+
+#include <cstring>
 #include <filesystem>
 #include <spanstream>
-#include <sstream>
 #include <string>
 #include <vector>
 
@@ -114,24 +116,41 @@ std::map<std::string, std::vector<float>> RifVtkImportUtil::readProperties( cons
         if ( name && *name )
         {
             std::vector<float> values;
-            std::istringstream iss( dataArray.text().get() );
+            const char*        text    = dataArray.text().get();
+            const char*        ptr     = text;
+            const char*        textEnd = text + std::strlen( text );
 
-            std::string token;
-            while ( iss >> token )
+            while ( *ptr != '\0' )
             {
-                if ( token == "nan" || token == "NaN" || token == "NAN" )
+                // Skip whitespace
+                while ( *ptr == ' ' || *ptr == '\t' || *ptr == '\n' || *ptr == '\r' )
+                    ++ptr;
+
+                if ( *ptr == '\0' ) break;
+
+                // Check for NaN (case-insensitive). ptr[3] is safe because text is null-terminated,
+                // so if ptr points to the last three chars "nan", ptr[3] == '\0' which matches the condition.
+                if ( ( *ptr == 'n' || *ptr == 'N' ) && ( ptr[1] == 'a' || ptr[1] == 'A' ) && ( ptr[2] == 'n' || ptr[2] == 'N' ) &&
+                     ( ptr[3] == '\0' || ptr[3] == ' ' || ptr[3] == '\t' || ptr[3] == '\n' || ptr[3] == '\r' ) )
                 {
                     values.push_back( std::numeric_limits<float>::quiet_NaN() );
+                    ptr += 3;
+                    continue;
                 }
-                else
+
+                // Parse float directly using fast_float
+                float fValue       = 0.0f;
+                auto  result       = fast_float::from_chars( ptr, textEnd, fValue );
+                auto* parsedEndPtr = result.ptr;
+
+                if ( result.ec != std::errc() || parsedEndPtr == ptr )
                 {
-                    double value = 0.0;
-                    bool   isOk  = RiaStdStringTools::toDouble( token, value );
-                    if ( isOk )
-                        values.push_back( static_cast<float>( value ) );
-                    else
-                        return {};
+                    // Failed to parse
+                    return {};
                 }
+
+                values.push_back( fValue );
+                ptr = parsedEndPtr;
             }
 
             if ( !values.empty() )

ApplicationLibCode/GeoMech/GeoMechFileInterface/RifVtkReader.cpp

@@ -256,27 +256,18 @@ std::expected<RigElementType, std::string>
         auto piece = grid.child( "Piece" );
         if ( !piece ) return std::unexpected( "Missing Piece tag: " + d.filepath.string() );
 
-        // Read points
-        std::vector<cvf::Vec3d> vertices = RifVtkImportUtil::readPoints( piece );
-        if ( vertices.empty() ) return std::unexpected( "No points found: " + d.filepath.string() );
-
-        // Read connectivity
-        std::vector<unsigned> connectivity = RifVtkImportUtil::readConnectivity( piece );
-        if ( connectivity.empty() ) return std::unexpected( "No connectivity found: " + d.filepath.string() );
-
-        // Read connectivity
-        std::vector<cvf::Vec3f> partDisplacements = RifVtkImportUtil::readDisplacements( piece );
-        if ( partDisplacements.empty() ) return std::unexpected( "No displacements found: " + d.filepath.string() );
-
-        RiaLogging::info( QString( "Found %1 vertices, %2 connectivities, and %3 displacements." )
-                              .arg( vertices.size() )
-                              .arg( connectivity.size() )
-                              .arg( partDisplacements.size() ) );
-
         // Use the geometry from the first time step only.
         // The geometry is assumed to not change between time steps.
         if ( isFirst )
         {
+            // Read points
+            std::vector<cvf::Vec3d> vertices = RifVtkImportUtil::readPoints( piece );
+            if ( vertices.empty() ) return std::unexpected( "No points found: " + d.filepath.string() );
+
+            // Read connectivity
+            std::vector<unsigned> connectivity = RifVtkImportUtil::readConnectivity( piece );
+            if ( connectivity.empty() ) return std::unexpected( "No connectivity found: " + d.filepath.string() );
+
             std::vector<std::pair<int, cvf::Vec3d>> partNodes;
             for ( int i = 0; i < static_cast<int>( vertices.size() ); i++ )
             {
@@ -303,8 +294,18 @@ std::expected<RigElementType, std::string>
 
             elementType = RigElementType::HEX8P;
         }
+
+        // Read displacements for all timesteps
+        std::vector<cvf::Vec3f> partDisplacements = RifVtkImportUtil::readDisplacements( piece );
+        if ( partDisplacements.empty() ) return std::unexpected( "No displacements found: " + d.filepath.string() );
+
         const std::map<std::string, std::vector<float>> partProperties = RifVtkImportUtil::readProperties( piece );
 
+        RiaLogging::info( QString( "Found %1 displacements and %2 properties for timestep %3." )
+                              .arg( partDisplacements.size() )
+                              .arg( partProperties.size() )
+                              .arg( d.timestep ) );
+
         properties[partId].push_back( partProperties );
         displacements[partId].push_back( partDisplacements );